READING MATERIAL QUIZ #1 AND #2

FORCES

(MC-01-AD-001) Physics is applied to biological and physiological systems both at a macroscopic and at a

microscopic level. The textbook provides reference to both; we study the effect of gravity on the otoliths in

the macula of the inner ear and we study the effect of gravity on the entire human body. Otoliths have sizes

in the range of about 5 micrometre and the human body has a size of about 2 m. Thus, the force concept has

physiological relevance at least over 6 orders of magnitude in length of an object.

In the current context we want to focus on an example of a macroscopic application of the force concept, however, not to the entire human body but to a body part. This is possible as the attached illustrates and many examples in the textbook rely on this approach. In the attached figure we consider the three forces T, Warm and F. Which of the three forces in the figure is/are contact forces?

A. all three forces

B. T and Warm

C. T and F

D. Warm and F

Answer Key: C

(MC-01-AD-002) Physics is applied to biological and physiological systems both at a macroscopic and at a microscopic level. The textbook provides references to both; we studied the effect of gravity on the otoliths in the macula of the inner ear and we studied the effect of gravity on the entire human body. Otoliths have sizes in the range of about 5 micrometre and the human body has a size of about 2 m. Thus, the force concept has physiological relevance at least over 6 orders of magnitude in length of an object.

In the current context we want to focus on an example of a macroscopic application of the force concept, however, not to the entire human body but to a body part. This is possible as the attached figure illustrates and many examples in the textbook rely on this approach. In the figure we consider the three forces T, Warm and F. The dumbbell has a weight Wdumbbell. Why do we not include this force in the list of forces we consider in the text above for the shown figure?

A. The force Wdumbbell acts in another direction than the listed forces and has therefore to be omitted.

B. The force Wdumbbell has no reaction force in the figure, and for that reason cannot be considered in Newton's laws.

C. The force Wdumbbell does not act on the person's arm and has to be excluded when Newton's law is applied to the arm.

D. We have already included the weight of the arm, Warm and there is no way to include two different weights in Newton's laws.

E. The dumbbell is not alive and can therefore not exert a force on another object.

Answer Key: C (MC-01-AD-003) Tension is:

A. A contact-free force

B. A contact force

C. A specific form of energy

D. A pressure value corrected for the air pressure

Answer Key: B (MC-01-AD-004) Two objects are connected with a string. In the quantitative treatment of the problem we assume that the string exerts a tension force of magnitude T on each of the two objects. Which of the following assumptions is both necessary and sufficient for us to introduce T as discussed above?

A. the string may hang loose between the objects

B. the string does not pass over a pulley

C. the string is massless

D. the two objects are not on a collision course with each other

E. none of the above

Answer Key: C (MC-01-AD-005) We consider an astronaut on the moon standing on a scale. Hint: the astronaut is not in the biosphere, so we need to look at Newton's law of gravity, which you find in the textbook. Don't worry, this is the only out-of-the-biosphere question I have in this set (as far as I recall). The reading of the scale is less than that on Earth because:

A. The astronaut lost body mass on the flight to the moon

B. The gravitational constant G is different on the moon

C. The mass of the moon is less than the mass of the Earth

D. The air the astronaut carries in a tank pulls him/her upwards

Answer Key: C (MC-01-AD-008) Which of the following forces is not a convenience force?

A. Tension

B. Normal Force

C. Weight

D. External force (specifically: the force you exert to push a pen across the table)

E. All fours choices (a) through (d) are convenience forces

F. More than one of the choices (a) through (d) are convenience forces

Answer Key: C C-01-AD-009) The term “normal” in normal force means the same as perpendicular. Which plane is perpendicular to the normal force?

A. Any plane that includes the direction vertically down toward the centre of Earth

B. Any plane that includes the line along the horizon (usually called a horizontal plane)

C. The surface of the object of interest that touches the object that exerts the normal force on the object of interest

D. The surface of the object that causes the normal force on the object of interest, and is in contact with the object of interest

E. None of the above

Answer Key: D (MC-01-AD-010) Which of the following must be the case for a string observed in a sketch of a problem to be associated with a tension force in a subsequent calculation using Newton’s laws? Careful – always read all options because more than one choice may apply, which then requires to pick the respective statement

A. The string must be taut

B. The string must be attached to the object of interest

C. The string must be reasonably short

D. The string must be attached on at least one other object besides the object of interest

E. All fours choices (a) through (d) must be the case

F. More than one of the choices (a) through (d) must be the case

G. None of the choices (a) through (d) must be the case

Answer Key: F

(MC-01-AD-011) Which of the following forces has always the same orientation relative to the vertical direction?

A. weight

B. normal force

C. tension

D. All three choices (a) through (c)

E. More than one of the choices (a) through (c)

F. None of the choices (a) through (c)

Answer Key: A

(MC-01-AD-012) In a particular problem in mechanics, you identify an object of interest. What (additional) information do you need about the object of interest to use its weight in a calculation?

A. I need its size (spatial dimensions)

B. I need its volume

C. I need its mass

D. I need its colour

E. I need no other information that the identity of the object

F. I need more information than offered in choices (a) through (d). Choose this answer if, for example, you need its mass and its volume.

Answer Key: C

(MC-01-AD-013) The normal force can never be directed in the following direction:

A. Vertically down

B. Vertically up

C. In a horizontal direction

D. There is no restriction on the possibilities of directions in which the normal force can point.

E. There are some restrictions on the direction of the normal force, but none of choices (a) through (c) captures these properly

Answer Key: D

READING MATERIAL QUIZ #3 AND #4

NEWTON’S LAWS

(MC-01-AM-001) All forces in this problem act on an object along the same axis. The components along that axis for the two forces are F = - 5 N and f = +10 N. To bring the object into mechanical equilibrium, we ...

A. ... do nothing, the equilibrium is already established

B. ... exert a third force with its component along the same axis to be + 5 N

C. ... exert a third force with its component along the same axis to be - 5 N

D. ... exert a third force with its component along the same axis to be - 10 N

E. ... exert a third force with its component along the same axis to be - 15 N

Answer Key: C

(MC-01-AM-003) Two forces act on an object. The first force we call F. This force has the magnitude F = + 5 N and acts in the positive x-direction. If the object does not accelerate, what do we know about a second force f?

A. The magnitude of force f is f = 0 N

B. The x-component of force f is + 5 N

C. The x-component of force f is - 5 N

D. The y-component of force f is + 5 N

E. The y-component of force f is - 5 N

Answer Key: C

(MC-01-AT-001) An object of mass m accelerates with acceleration magnitude a. How does the magnitude of the acceleration change if we double the mass of the object but keep the accelerating force unchanged?

A. The acceleration remains unchanged

B. The acceleration doubles

C. The acceleration increases four-fold

D. The acceleration is halved

E. None of the above

Answer Key: D

(MC-01-AT-002) We study the various free-body diagrams shown in the figure below. Which combination of cases of free-body diagrams represent systems which cannot be in mechanical equilibrium?

A. Cases 1, 2, and 5.

B. Cases 1, 3, 4, and 6.

C. Cases 2 and 5.

D. Cases 3, 4, and 6.

E. Cases 1, 4, and 6.

Answer Key: D

(MC-01-AT-004) We study the hand of an athlete just about to release a javelin in a track and field event. When would you use Newtons second law to describe its motion?

A. When it moves rather slow

B. When it moves very fast

C. When it moves faster and faster

D. When it is held at rest

Answer Key: C

(MC-01-AT-005) We used a figure similar to the one below in the textbook to discuss a system in mechanical equilibrium. Under which condition is the shown system NOT in mechanical equilibrium

A. The system is for all combinations of m and M in equilibrium

B. m < M

C. m = M

D. m > M

Answer Key: D

(MC-01-AZ-001) Physics is applied to biological and physiological systems both at a macroscopic and at a microscopic level. The textbook provides references to both; we studied the effect of gravity on the otoliths in the macula of the inner ear and we studied the effect of gravity on the entire human body. Otoliths have sizes in the range of about 5 micrometre and the human body has a size of about 2 m. Thus, the force concept has physiological relevance at least over 6 orders of magnitude in length of an object.

In the current context we want to focus on an example of a macroscopic application of the force concept, however, not to the entire human body but to a body part. This is possible as the attached figure illustrates and many examples in the textbook rely on this approach. In the figure we consider the three forces T, Warm and F. Due to Newton's third law we can make the following statement:

A. The arm exerts on the trunk a force which equals - T.

B. The weight Warm is equal in magnitude to the tension T.

C. Forces Warm and T are a action/reaction pair of forces.

D. Forces Warm and F are a action/reaction pair of forces.

E. The weight of the arm has no reaction force.

Answer Key: A

(MC-01-AZ-002) Two objects X and Y are in contact. What does Newton's third law state about the interaction

forces between the objects?

A. The two forces act in the same direction on object Y

B. The two forces act in opposite directions on object X

C. FX on Y = FY on X (Note that both forces are printed in bold-face)

D. FX on Y = - FY on X (Note that both forces are printed in bold-face)

E. The two forces are the same

Answer Key: D

(MC-01-AZ-003) We discuss the figure below and its figure caption. Note that the figure shows a person doing push-ups. The question assesses how the various forces in the lower leg are connected. Choose which of the following statements is correct: "We may need Newton's third law to describe the interaction between the bone, the tendon and the muscle because ..."

A. the tendon is modelled as a point mass

B. we always need all three of Newton's laws to deal with mechanical problems

C. we may not have enough information about the object of interest in a stated problem about the person

D. Newton's third law is required to solve all problems in kinesiology

E. we do not need Newton's third law to solve a problem stated about the person doing push-ups.

Answer Key: C

(MC-01-AZ-004) A spider hangs from its spider silk string, half way down from a leaf. Is the following statement correct? "The silk string pulls the spider up, and this represents the reaction force to the spider's weight acting downward"

A. Yes, always

B. Yes, but with some exemptions

C. Most of the time no, but it works in a few cases

D. No, never

Answer Key: D

(MC-01-AZ-005) How can any object accelerate when Newtons third law states that there is a reaction force to every force we apply to accelerate an object?

A. Because we can often neglect the reaction force

B. Because the action force is always larger in magnitude than the reaction force

C. Because we can apply the action force such that it and the reaction force act both in the same direction

D. None of the above explanations is correct

Answer Key: D

READING MATERIAL QUIZ #5

FRICTION

(MC-01-BB-001) You attempt to pull two objects across the floor in your room. Object I gives in and you succeed, but object II stays unmoved even though you use all your might. What can we conclude from these observations?

A. The coefficient of kinetic friction of the floor is particularly large

B. The coefficient of static friction exceeds the coefficient of kinetic friction

C. Object I is heavier than object II

D. Object I is lighter than object II

E. Object I is bigger than object II

F. Object I is smaller than object II

Answer Key: D

(MC-01-BB-002) You pull an object across the floor in your room. Initially you fail, but as you pull harder, you succeed. Once in motion, a slightly lesser force is needed to keep the object moving with constant speed. What can you conclude from this observation?

A. The coefficient of kinetic friction of the floor is particularly large

B. The coefficient of static friction exceeds the coefficient of kinetic friction

C. The object is very heavy

D. The object is very big

Answer Key: B

(MC-01-BB-003) You want to pull an object across the floor in your room. You attach a rope to the object and, facing the object and with both hands holding the rope, you pull horizontally with all your might. Alas, the object does not move at all. What suggestion might help you overcome the problem, so that you can move the object to another place in your room?

A. Turn, lay the rope over your shoulder and hold it in front of your chest facing away from the object. Now the rope is stretched under an upwards angle from the object to your shoulder. Pull with the same strength as before.

B. Drop the rope, walk behind the object and rather push it with the same force you applied before.

C. Go on your knees behind the object, and push it under a slight upwards angle, reasoning that the upwards component of the applied for compensates somewhat the weight of the object. Keep in mind though, your physical strength to apply a force has not increased.

D. It is hopeless, at least the choices (A) through (C) are not worth trying.

Answer Key: D

(MC-01-BB-004) Assume the unrealistic case that the coefficient of static friction for a particular object on a particular surface is smaller than the coefficient of kinetic friction. In an experiment with this system, the object is pulled across the surface with a constant force such that the object slows down steadily. What happens next? (Think about whether you ever saw this actually happen.)

A. The object slows down to a particular speed, then moves with constant speed

B. The object slows down to rest, then stays at rest

C. The object comes momentarily to a halt, but then moves again, reaching a terminal speed

D. The object comes momentarily to a halt, moves again, comes to a halt again, and so on, that is, it seems to move in small bursts

E. The objects slows down and then accelerates in the opposite direction

Answer Key: D

(MC-01-BB-005) You are pushing a picture frame against the wall for your room mate to assess whether it is the best location before hammering a nail into the wall. In which of the following cases do you rely on the coefficient of kinetic friction to be sufficiently large?

A. When you push the picture frame under an upwards angle and it doesn’t move

B. When you push the picture frame horizontally and it doesn’t move

C. In both cases (A) and (B) above

D. In neither one of the cases (A) or (B) above

Answer Key: D

(MC-01-BB-006) An object is placed on an inclined plane that forms an angle Θ with the horizontal. The object starts to move downhill with a certain speed. You want to repeat the experiment but want the object to stay stationary on the incline. Which of the following changes MUST you do in order to have a chance that the outcome of your second experiment is as intended?

A. increase the angle Θ

B. decrease the angle Θ

C. set the angle Θ = 00, i.e., lower the incline surface to be horizontal

D. None of the choices (A) through (C) will suffice

Answer Key: B

MC-01-BB-007) Which of the following sports would look most similar to what you are used from TV if friction were somehow turned off?

A. Soccer

B. Ice Hockey

C. 100 m sprint

D. Diving from 10 m platform

E. Baseball

Answer Key: D

(MC-01-BB-008) Consider a glass of water standing on your kitchen table. If we allow for a moment that both the kinetic and the static coefficients of friction were set to zero, what would happen?

A. Nothing, the glass stays were it was

B. The glass starts to slide to the edge of the table and fall off

C. The water would drain out of the glass and spill over the table

D. The glass would take off and hover above the table at low altitude

E. The glass would encounter an infinite acceleration, that is, it would disappear faster than a speeding bullet

F. We would see what H. G. Wells described in the “Time Machine”: the glass would become faint and fainter until it is gone as it would disappear into the future

Answer Key: A

(MC-01-BB-009) Assume that we find a magic table that displays an infinitely large static coefficient of friction when a particular piece of wood is placed on it. Which of the following observations would be made?

A. The piece of wood would slide easily across the table when touched just weakly

B. The piece of wood would react to exerted forces pretty much as we observe it for any piece of wood in everyday cases

C. The piece of wood would become immovable unless lifted off the surface, as if glued to the table

D. No such statement as in (A) through (C) can be made as there is no experimental case known to test the predictions

Answer Key: C

(MC-01-BB-010) An object is pulled up an inclined plane by a massless string. On which of the following forces does the friction force between incline and the object depend?

A. The object’s weight

B. The normal force acting on the object

C. The tension in the string

D. The net force acting on the object

Answer Key: B

READING MATERIAL QUIZ #6

TORQUE AND ROTATIONAL EQUILIBRIUM

(MC-14-AA-001) Which of the following processes can happen with a rigid object (using the scientific/physics definition of the term rigid)?

A. Bend

B. Break

C. Stretch

D. Rotate

E. Twist

Answer Key: D

(MC-14-AA-002) Which of the following processes cannot happen with a rigid object (using the scientific/physics definition of the term rigid)?

A. Move with constant speed along a straight line

B. Accelerate along a straight line

C. Rotate at constant number of revolutions

D. Stay at rest

E. Vibrate

Answer Key: E

(MC-14-AA-003) A person holds their upper arm vertical and the lower arm horizontal, i.e., with an angle

between lower and upper arm of 900. A second person wants to place an object of mass M on the person’s

arm such that the person has greatest possible trouble to continue to hold the arm as before. Where would the second person place the object of mass M?

A. In the person’s hand

B. Midway between the hand and the elbow

C. Close to the elbow

D. The effort to hold the lower arm in the original position is the same where ever the object is placed

Answer Key: A

(MC-14-AA-004) A person holds their upper arm vertical and the lower arm horizontal, i.e., with an angle

between lower and upper arm of 900. A second person wants to force this person to lower their lower arm by

pushing the person’s hand. In which direction should the second person push to most likely succeed?

A. Push the hand toward the elbow

B. Pull the hand away from the elbow

C. Push vertically down

D. Push under an angle of 450 with the horizontal, down and toward the elbow

E. Push the hand sideways

Answer Key: C

(MC-14-AA-005) A person holds their upper arm vertical and the lower arm horizontal, i.e., with an angle

between lower and upper arm of 900. A second person wants to force this person to lower their lower arm by

pushing the person’s hand. Should the second person use as large as possible a force to most likely succeed?

A. Yes

B. No, using a smaller force will be better

C. We cannot decide this question based on the Physics discussed in class

Answer Key: A

(MC-14-AA-006) Inspect the five attached figures, labelled Figs. 5.3 through 5.7. Which of the shown joints is

best represented by a single axis of rotation?

A. All joints

B. The joints in Figs. 5.3 and 5.5

C. The joints in Figs. 5.4 and 5.7

D. The joints in Figs. 5.6 and 5.7

E. Only the joints in Fig. 5.5

F. None of the figures shows a joint that is best represented by a single axis.

Answer Key: D

(MC-14-AA-007) The attached figure shows a person’s lower arm. Note that the biceps muscle of the upper arm is attached to the lower arm close to the elbow joint. The biceps allows us to pull the stretched lower arm up, for example into the posture shown in the figure. If we were to redesign the lower arm and attach a then significantly longer biceps muscle close to the wrist, what would be the benefit of such an arrangement? Hint: answer based on the physics principles we discussed in class.

A. The lower arm can be moved through a wider range of angles with the upper arm

B. A greater force can be exerted to hold an object in the hand (e.g., the green cylinder in the figure could be heavier)

C. Both answers (A) and (B) are correct

D. No benefit could be envisaged

Answer Key: B

(MC-14-AA-008) A (simplifying) assumption we make is that the axis of rotation for a particular problem we study is fixed in space. This means, we do not study a baseball bat that slides out of the hands of a batter while swinging to hit a baseball. Inspect the particular joint in the attached figure. Would this be a joint we study in the lecture series for this course?

A. Yes

B. No

Answer Key: B

(MC-14-AA-009) The attached figure shows five locations of the fulcrum along a red bar upon which five equal in magnitude forces (blue arrows) act as shown. Which of the five cases must be in rotational equilibrium? Note: Choose (F) and (G) is none or more than one cases answer the question.

A. (A)

B. (B)

C. (C)

D. (D)

E. (E)

F. None of the five cases must be in rotational equilibrium

G. More than one of the five cases must be in rotational equilibrium

Answer Key: F

(MC-14-AA-010) Inspect the attached figure. It shows a bar that is hinged at a vertical wall and held by a cable attached to its far end. In addition, an object of mass M is placed on the bar. What is the minimum number of distinguishable forces that act on the bar which could cause individually a rotation about the hinge?

A. None

B. One

C. Two

D. Three

E. Four

F. Five or more

Answer Key: D

(MC-14-AA-011) In problems regarding the rotational equilibrium of rigid bodies, we always draw the weight of the system as a force to the position of the centre of mass. Inspect the system of bottle and wine holder in the attached figure. The system could rotate about the axis formed where the wine holder sits on the underlying table surface; however, the system is in rotational equilibrium. What does this tell us about the position of the centre of mass for the combined system of bottle and wine holder?

A. Nothing

B. That it is above the table

C. That it is located vertically above the axis referred to in the question text

D. That it is at the point where the bottle and the the wine holder touch each other

E. That it is near the lower end of the bottle, in the vicinity of the upside-down letter “S” printed on the label

Answer Key: C

RM QUIZ #7

ENERGY

(MC-02-CE-001) A person tries to pull an object with an external force F upward; however, the person is too weak and the object drops to the ground under its own weight W. Which of the following statements is correct?

A. Because the person did not succeed, no work is done in this experiment.

B. The person has done work on the object; this work is calculated as Work = F Δs in which Δs is

the distance through which the object fell.

C. The person has done work on the object; this work is calculated as Work = W Δs in which W is

the weight of the object.

D. The object has done work on the person; this work is calculated as Work = W Δs in which W is

the weight of the object.

E. The object has done work on the person; this work is calculated as Work = F Δs

Answer Key: E

(MC-02-CE-002) If an object is pulled with force F = 10 N for a distance d = 2 m, the origin of the force has done the following work (absolute value only):

A. W = 2 N m

B. W = 20 N m

C. W = 2 N/m

D. W = 5 N/m

E. W = 20 N/m

Answer Key: B

(MC-02-CE-003) The attached figure shows an object that slides a distance d = 3 m down along an inclined frictionless surface. A person pushes the object into the incline, with the force F. The direction of this force is shown by the black arrow, and its magnitude is F = 7 N. What is the absolute value of the work

done by the object on the person? Use Θ = 40o.

A. 20 J or more

B. more than 13 J, but less than 20 J

C. more than 7 J, but less than 13 J

D. less than 7 J

Answer Key: D

(MC-02-CK-001) Which is the standard unit for energy?

A. N

B. J/s

C. N m

D. Pa

E. N/J

Answer Key: C (MC-02-CK-002) What is the potential energy of the hippo in the attached figure?

A. Epot > 0

B. Epot = 0

C. Epot < 0

D. Whatever I want it to be

Answer Key: D (MC-02-CN-001) How does the kinetic energy of an object change when its speed is reduced to 50% of its initial value?

A. The kinetic energy remains unchanged

B. The kinetic energy becomes 50% of the initial value

C. The kinetic energy becomes 25% of the initial value

D. The kinetic energy doubles

E. The kinetic energy increase four-fold

Answer Key: C

(MC-02-CN-002) The figure below shows five curves with the vertical axis identified as the energy. We consider two forms of energy, (I) the kinetic

energy which we want to illustrate as a function of speed of the object (v), and (II) the total or internal energy of an isolated object, which we want to illustrate as a function of vertical position (y). Which combination of sketches from the figure below represents correctly the kinetic energy as a function of the speed and the internal energy as a function of vertical position?

A. Sketch (i) shows both the kinetic energy and the internal energy.

B. Sketch (i) shows the kinetic energy and sketch (ii) shows the internal energy.

C. Sketch (iv) shows the kinetic energy and sketch (i) shows the internal energy.

D. Sketch (v) shows the kinetic energy and sketch (ii) shows the internal energy.

E. Sketch (v) shows the kinetic energy and sketch (iii) shows the internal energy.

Answer Key: E

(MC-02-CN-003) An (ice) hockey player shoots a puck from the ice surface at 3 metres in front of the goalie and scores into the upper left corner of the goal. At what instant is the kinetic energy of the puck the greatest?

A. It is always the same, kinetic energy is conserved

B. Just after it leaves the hockey stick of the player

C. When it passes the goalie

D. Just before it hits the net at the back of the goal

Answer Key: B

(MC-02-CN-004) The attached figure shows two objects of different but unknown masses on a frictionless surface and connected with a massless string. A person pulls with an external force to the right. We study

the system from the instant the objects start at rest until the object of mass m2 is pulled by a distance of 2

m to the right. Which object has at the end of the process the higher kinetic energy?

A. The object of mass m2

B. The object of mass m1

C. Neither, their final kinetic energy is equal

D. We cannot tell with the given information

Answer Key: D

(MC-02-CQ-001) An object of mass 0.5 kg is thrown vertically upward at a speed of 30 m/s. What is the kinetic energy of the object at the highest point of its trajectory?

A. 0 J

B. 225 J

C. 15.0 J

D. 450 J

E. -15.0 J

Answer Key: A

(MC-02-CQ-002) In a mechanical experiment with an isolated object, only Ekin and Epot of the object change.

If the object accelerates from 5 m/s to 10 m/s, its potential energy has:

A. not changed

B. decreased by a factor of 2

C. decreased by a factor of 4

D. decreased by a factor we cannot determine from the problem as stated

E. increased

Answer Key: D

READING MATERIAL QUIZ #8 AND 9

GASES

(MC-03-EE-001) Charles' law can be written as V/T = const if ...

A. ... V is measured in non-standard unit cm3

B. ... T is measured in non-standard unit degree Celsius (oC)

C. ... the pressure varies moderately

D. ... the gas is a real noble gas, let's say xenon

E. None of the above

Answer Key: A

(MC-03-EE-002) Consider an ideal gas at -5oC and 0.5 atm with a density of 0.091 kg/m

3. What is the molar

mass of this gas?

A. M = 2 g/mol (H2)

B. M = 4 g/mol (He)

C. M = 16 g/mol (CH4)

D. M = 28 g/mol (N2)

E. M = 30 g/mol (C2H6)

F. M = 32 g/mol (O2)

G. M = 44 g/mol (CO2)

Answer Key: B

(MC-03-EE-003) Consider an ideal gas at -5oC and 0.5 atm with a density of 0.636 kg/m

3. What is the molar

mass of this gas?

A. M = 2 g/mol (H2)

B. M = 4 g/mol (He)

C. M = 16 g/mol (CH4)

D. M = 28 g/mol (N2)

E. M = 30 g/mol (C2H6)

F. M = 32 g/mol (O2)

G. M = 44 g/mol (CO2)

Answer Key: D

(MC-03-EE-004) Consider an ideal gas at -5oC and 0.5 atm with a density of 1.0 kg/m

3. What is the molar mass

of this gas?

A. M = 2 g/mol (H2)

B. M = 4 g/mol (He)

C. M = 16 g/mol (CH4)

D. M = 28 g/mol (N2)

E. M = 30 g/mol (C2H6)

F. M = 32 g/mol (O2)

G. M = 44 g/mol (CO2)

Answer Key: G

(MC-03-EE-005) In Boyle's experiment, the volume of the sealed gas decreases as additional mercury is added to the open column. This effect is due to:

A. the fact that the volume of the gas decreases

B. the fact that pressure and volume are linearly proportional to each other

C. the fact that pressure and volume are proportional to each other

D. the fact that pressure and volume are inversely proportional to each other

E. the fact that pressure and volume are unrelated

Answer Key: D

(MC-03-EE-006) We consider 1 mol of an ideal gas under isothermal conditions. If the pressure is doubled ...

A. ... the volume remains unchanged

B. ... the volume doubles as well

C. ... the volume is halved

D. ... the volume is increased by a factor 4

E. ... the volume decreases to 25% of its original value

Answer Key: C

(MC-03-EE-007) We study the ideal gas law. The gas constant can be given in different units, however, this unit is wrong:

A. J/(K mol)

B. (atm m3)/(K mol)

C. (Pa cm2)/(K mol)

D. cal/(K mol)

E. None of the above, all are suitable for the gas constant R

Answer Key: C

(MC-03-EE-008) Rewrite the ideal gas law by combining n and V as ρ/M, in which ρ is the density of the gas (in unit kg/m

3) and M is the molar weight (in unit kg/mol). Which parameter in this rewritten ideal gas

law MUST decreases from inside to outside across the envelope of a hot air balloon for it to stay airborne?

A. pressure p

B. temperature T

C. gas density ρ

D. none or more than one of these parameters increases from inside to outside

Answer Key: B (MC-03-EJ-001) 1 mol of hydrogen gas, which we treat as an ideal gas of molecular mass M = 2 g/mol, is held

at 50oC. Which of the following values is closest to the root-mean-square speed of the atoms in this gas?

A. 2007 m/s

B. 63.5 m/s

C. 4,028,100 m/s

D. 790 m/s

E. 25.0 m/s

Answer Key: A

(MC-03-EJ-002) The ideal gas law is a macroscopic description of a gas, i.e., all parameters can be measured without a model of the microscopic properties and structure of the gas. Still, when Boltzmann, Maxwell and Clausius developed such a model, called the kinetic gas theory, our understanding of the atomic and molecular nature of gases advanced. In their model, which of the following is a result, not an assumption made to develop the model?

A. The gas consists of a very big number of point masses, i.e., the combined volume of all particles is negligible compared to the size of the container.

B. The internal energy of an ideal gas depends linearly on the temperature (in unit kelvin).

C. The molecular size is much smaller than the inter-particle distance.

D. The molecules are in continuous random motion, traveling along straight lines while not colliding with other particles or the walls.

E. Collisions with each other and the container walls are elastic, which excludes attractive intermolecular interactions.

Answer Key: B

(MC-03-EJ-004) We compare two components of the air in a typical lecture hall: oxygen (O2 , M = 32 g/mol)

and nitrogen (N2, M = 28 g/mol). What is true?

A. The oxygen molecules are slightly hotter than the nitrogen molecules

B. The oxygen molecules are slightly cooler than the nitrogen molecules

C. The oxygen molecules are slightly faster than the nitrogen molecules

D. The oxygen molecules are slightly slower than the nitrogen molecules

E. Both types of molecules have each the same temperature and the same velocity distribution

Answer Key: D

(MC-03-EJ-005) A 7.5 L container is filled with air (M = 29 g/mol, treated as an ideal gas) to a pressure of

pinitial = 1.5 atm at Tinitial = + 500C. Then the gas is compressed to a final volume of 3.5 L with final pressure

pfinal = 4.5 atm at Tfinal = 315 K. In this process, how did the root-mean-square speed of the air change?

A. it remained unchanged

B. it increased

C. it decreased

D. too many parameters vary in this process to answer this with certainty

Answer Key: C

(MC-02-CG-001) Air, initially at 1 x 105 Pa, is sealed in a container by a mobile piston of cross-sectional area

10.0 cm2. Now we push the piston with a force of F = 100 N to compress the air. What is the final pressure p

of the sealed air when the piston is held in mechanical equilibrium? (Choose the closest value)

A. p = 2 x 104 Pa

B. p = 1.0001 x 105 Pa

C. p = 2 x 105 Pa

D. p = 1 x 106 Pa

E. None of the above

Answer Key: C

RM QUIZZES #10 AND 11

STATIC FLUIDS

(MC-07-MD-001) In a hydraulic lift as shown in the figure below, if the diameter of the smaller piston is 4.0 cm and the diameter of the larger piston is 40.0 cm, what weight can the larger piston support when a force of 250 N is applied to the smaller piston?

A. 2.5 N

B. 25 N

C. 250 N

D. 2500 N

E. 25, 000 N

Answer Key: E

(MC-07-MD-003) Using linear axes, which of the five plots of pressure versus depth below describes Pascal's law correctly?

A. plot A

B. plot B

C. plot C

D. plot D

E. plot E

Answer Key: B (MC-07-MD-004) We apply Pascal's law to an unknown fluid in an open container. In this container we observe that the pressure is 1.5 atm at 0.5 m below the surface. At what depth in this fluid is the pressure 1.8 atm?

A. 20 cm

B. 40 cm

C. 80 cm

D. 120 cm

E. 2.5 m

Answer Key: C

(MC-07-MD-005) We introduce Pascal's law in two forms; one of these is written as: p = patm + ρ g d. Which of

the following is true?

A. The pressure decreases with depth below the surface

B. The pressure is zero at the surface (d = 0)

C. The positive depth axis points vertically downwards

D. The formula can be applied to the atmosphere if d is measured upwards

E. The formula applies in the same form to a beaker of water on the surface of the moon

Answer Key: C

(MC-07-MD-006) We study water of 1.0 g/cm3 density. If we measure the pressure first at a depth d and find

the value p1, and then at twice that depth to find p2, the two results are related in this form:

A. p1 > p2

B. p1 = p2

C. 2 p1 > p2

D. 2 p1 = p2

Answer Key: C (MC-07-MH-001) A hot air balloon floats in mid air because in it we removed air of a total mass equal to the mass of the balloon. To rise higher, a gas burner is used to raise the temperature of the air in the balloon further. This works because

A. The pressure in the balloon is lowered

B. The volume of the balloon is expanded

C. The density of the gas in the balloon is increased

D. The number of moles of gas in the balloon is lowered

Answer Key: D

(MC-07-MH-002) Ice has a density of 917 kg/m3. Therefore it will

A. sink to the bottom of a beaker with tap water (density of tap water is 1.0 g/cm3)

B. sink to the bottom of a beaker with seawater of density 1025 kg/m3

C. sink to the bottom of a beaker with ethanol of density 0.79 g/cm3

D. float below the surface of the seawater of density 1025 kg/m3

E. float below the surface of ethanol of density 0.79 g/cm3

Answer Key: C

(MC-07-MH-004) The magnitude of the buoyant force on an object is expressed in the form:

Fbuoyant = ρfluid Vobject g. Thus, the buoyant force is proportional to:

A. The density of the object

B. The mass of the object

C. The volume of the fluid

D. The density of the medium surrounding the object

E. None of these options

Answer Key: D

(MC-07-MH-005) In this question we investigate a unique adaptation of a sea animal to the physical laws governing their marine environment. The Siamese fighting fish in the attached figure have an unusual way of caring for their young. Males prepare a home for their future offspring by taking gulps of air and blowing saliva-coated bubbles which collect at the water surface as a glistening froth. When a female arrives ready to mate, she swims under the bubble-nest where the male embraces her and fertilizes her eggs. Then, picking up the eggs in this mouth, the male spits them one by one into his bubbles. The role as a father continues for the male Siamese fighting fish as he carefully guards the developing eggs. Any that fall are immediately caught and spat back into a bubble. What statement can we make about the eggs of the fighting fish?

A. They are heavy

B. They are small in volume

C. Their density is greater than that of water

D. Their density is equal to that of water

E. None, the whole story is just a myth

Answer Key: C (MC-07-MH-006) In this question we investigate a way in which we humans take advantage of the buoyancy principle. The figure below shows the "Mindener Wasserstraßenkreuz", which literally translates as "the water canals' intersection at Minden." What happens when a boat passes over the bridge as shown?

A. The load on the bridge becomes heavier when a boat sails across the bridge

B. The load the bridge has to absorb remains the same as without the boat

C. The load on the bridge decreases as water spills over its edges

D. The picture is fake, the bridge would collapse with a heavy boat as shown sailing onto it

E. A boat can only pass over the bridge when another boat passes under the bridge to compensate the adverse effect of buoyancy

Answer Key: B (MC-07-MH-007) In this question we investigate a way in which we humans take advantage of the buoyancy principle. Study the lady in the figure shown as she floats effortlessly at the surface of water. What of the following is true?

A. This must be a hoax, humans cannot float like that on water, no matter what!

B. The lady vacations at a unique place where the water is extremely salty, increasing its density to a value well above that of the lady's body

C. This is a place in a private swimming pool with the water temperature significantly higher than in usual pools

D. The lady's bikini must be made of light cloths and she relies on a significant air pocket under her hat

Answer Key: B

(MC-07-MH-008) The zeppelin Hindenburg exploded on May 6, 1937, in Lakehurst, New Jersey. The

accident was due to this type of dirigible using hydrogen (H2, M = 2g/mol) as a gas. It carried up to 70

passengers and crew. Estimate how many passengers and crew the Hindenburg could have carried had they used helium gas (M = 0.004 kg/mol) instead. (Choose the closest number

A. 150 passenger and crew

B. 70 passenger and crew

C. 35 passenger and crew

D. crew only (five people)

Answer Key: C

(MC-07-MH-009) We study the first attached figure. Part (a) shows a sphere with radius r = 10 cm and

density ρa = 1.8 g/cm3 suspended in water. Part (b) of

the figure shows a wooden sphere of diameter d = 10 cm

(density ρb = 0.95 g/cm3) held under water by a string.

Which of the four free-body-diagrams (fbd) shown in the second attached figure correspond to the two cases in the first figure? Note: T is a tension, W is the weight and Fbuoy is the buoyant force.

A. The fbd sketch (a) belongs to the case shown in the first figure part (a) and the fbd in sketch (b) belongs to the case shown in the first figure part (b)

B. The fbd sketch (b) belongs to the case shown in the first figure part (a) and the fbd in sketch (c) belongs to the case in the first figure part (b)

C. The fbd sketch (c) belongs to the case shown in the first figure part (a) and the fbd in sketch (d) belongs to the case in the first figure part (b)

D. The fbd sketch (c) belongs to the case shown in the first figure part (a) and the fbd in sketch (a) belongs to the case in the first figure part (b)

E. The fbd sketch (c) belongs to the case shown in the first figure part (a) and the fbd in sketch (b) belongs to the case in the first figure part (b)

Answer Key: E (MC-07-MH-010) We study the three model steps discussed in the textbook for deriving Archimedes' principle (see first attached figure). In the first frame, an element of water is identified which has the same shape and size as block B. In the second frame, the water element is removed, leaving a void behind. In the third frame the block B is placed in the void. Assume that the block is made of steel. Which of the six free-body diagrams (fbd) shown in the second attached figure correspond to the three cases in the figure above? Note: W is the weight and Fbuoy is the buoyant force.

A. fbd c to frame 1; fbd e to frame 2; and fbd a to frame 3.

B. fbd f to frame 1; fbd c to frame 2; and fbd e to frame 3.

C. fbd b to frame 1; fbd e to frame 2; and fbd f to frame 3.

D. fbd f to frame 1; fbd c to frame 2; and fbd b to frame 3.

E. fbd b to frame 1; fbd c to frame 2; and fbd f to frame 3.

Answer Key: E

(MC-07-MH-011) Which is not a correct unit of the buoyant force?

A. N

B. kg m/s2

C. Pa m2

D. J/m

E. all of these are correct

Answer Key: E