(The MAPs Co.) Dr. M. H. Suckley & Mr. P. A. Klozik Email: [email protected].

http://www.ScienceScene.com (The MAPs Co.)

Dr. M. H. Suckley & Mr. P. A. KlozikEmail: [email protected]

MAP

Team

Motion

I. Introduction

II. Newton’s First Law

III. Newton’s Second Law

IV. Newton’s Third Law

Motion

I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . 3

II. Newton’s First Law . . . . . . . . . . . . . . . . . . . . 4

A. Motion 1. Measuring the Velocity of Various Objects . . . . . 6 2. Observing Motion of a Toy Car. . . . . . . . . . . . . . 5

B. Inertia

1. Fundamentals . . . . . . . . . . . . . . . . . . . . . . . 9

2. Using Your Marbles . . . . . . . . . . . . . . . . . . . 10

3. FUN With Inertia . . . . . . . . . . . . . . . . . . . . . 10

Motion

III. Newton’s Second Law . . . . . . . . . . . . . . . . . . . 11

A. Acceleration (change in velocity)

1. Observing Acceleration . . . . . . . . . . . . . . . . . . .12

2. Acceleration A More Complete Picture . . . . . . . . 13

B. Fundamentals of Force 1. Observing Forces (using the “Gizmo”) . . . . . . . . . 14

2. Finding The Forces . . . . . . . . . . . . . . . . . . . . . . 15

3. Types of Force. . . . . . . . . . . . . . . . . . . . . . . . . . 24

4. Forces in a Collision . . . . . . . . . . . . . . . . . . . . . 26

5. The Falling Cup . . . . . . . . . . . . . . . . . . . . . . . . 27

C. The Affect of Mass on Acceleration . . . . . . 28

Motion

IV. Newton’s Third Law . . . . . . . . . . . . . . . . . 29

A. Equal and Opposite . . . . . . . . . . . . . . . . . . .30

B. Equal and Opposite Another Look . . . . . . . . . 31

C. Making Formulas Out of Words . . . . . . . . . . . . 33

We Had A Great Time

forces

V = d / t

Prerequisite

Skill

Michigan Benchmarks for Motion

1. Describe or compare motions of common objects in terms of speed and direction.

Key concepts: Words--east, west, north, south, right, left, up, down. Speed words--fast, slow, faster, slower.

Real- world contexts: Motions of familiar objects in two dimensions, including rolling or thrown balls, wheeled vehicles, sliding objects.

2. Describe how forces (pushes or pulls) are needed to speed up, slow down, stop, or change the direction of a moving object.

Key concepts: Changes in motion--speeding up, slowing down, turning. Common forces--push, pull, friction, gravity. Size of change is related to strength of push or pull.

Real- world contexts: Playing ball, moving chairs, sliding objects.

3. Qualitative describe and compare motion in two dimensions.

Key concepts: Two- dimensional motion--up, down, curved path. Speed, direction, change in speed, change in direction.

Real- world contexts: Objects in motion, such as thrown balls, roller coasters, cars on hills, airplanes.

4. Relate motion of objects to unbalanced and balanced forces in two dimensions.

Key concepts: Changes in motion and common forces--speeding up, slowing down, turning, push, pull, friction, gravity, magnets. Constant motion and balanced forces. Additional forces--attraction, repulsion, action/ reaction pair (interaction force), buoyant force. Size of change is related to strength of unbalanced force and mass of object.

Real- world contexts: Changing the direction--changing the direction of a billiard ball, bus turning a corner; changing the speed--car speeding up, a rolling ball slowing down, magnets changing the motion of objects, walking, swimming, jumping, rocket motion, objects resting on a table, tug- of- war.

5. Design strategies for moving objects by application of forces, including the use of simple machines.

Real- world contexts: Changing the direction--changing the direction of a billiard ball, bus turning a corner; changing the speed--car speeding up, a rolling ball slowing down, magnets changing the motion of objects, walking, swimming, jumping, rocket motion, objects resting on a table, tug- of- war.

F = m x a

11

Future

Unit

1

Naïve ideas:

1. The distance an object travels and its displacement are always the same.

2. An object’s speed and velocity are always the same. 3. An object having inertia is always at rest. 4. Acceleration is always in a straight line. 5. Acceleration means that an object is speeding up. 6. The numerical value of acceleration is always a positive number.

60

Newton’s First Law

An object stays at rest or continues to move in a straight line at a constant speed unless acted on by a force.

V = d / t

Observing Motion

1.09.3500.320.320.320.31

1.14.5000.440.430.440.43

VelocityMeters/sec

Distancemeters

AverageSec.

Trial 3Sec.

Trial 2Sec.

Trial 1Sec.

Finish Point Starting Point

.50-meters

t0t1

0Equipment Set-Up6

Time

Distance

Object Distance Time Speed Average Distance Time Speed Average

1. Toy Cars

Battery Powered Car Pull Back Car

Trial 1

Trial 2

Trial 3

2. Flowing Water

400-ml. Beaker 250-ml. Beaker

Trial 1

Trial 2

Trial 3

3. Clock Hands

Wall Clock Wrist Watch With Second Hand

Trial 1

Trial 2

4. Bouncing Ball

Tennis Ball Super Ball

Trial 1

Trial 2

Trial 3

5. Sound

Speed of Sound

Trial 1

Trial 2

Trial 2

Measuring The Velocity of Various Objects

Time

• The interval between two events.

S

T

A

R

T

S

T

O

P

1

00 00 0000 03 25

Distance• The interval between two objects.

S

T

A

R

T

S

T

O

P

Measuring the Filling Speed of Water

a. Turn the water on at a moderate rate. Keep this flow constant for both beakers.

b. Fill the 400 ml. beaker with any amount (approximately one fourth of the beaker) of water, while timing (t).

c. Mark the top of the water, and measure its distance in meters from the bottom of the beaker to the top of the water.

d. Repeat this for two additional readings. e. Compute the distance (x) the water level rose using: x1 = L1 - L0 x2 = L2 - L1 x3 = L3 - L2f. Compute the velocity of water flow using: v = x / t. g. Repeat this for two additional readings. h. Obtain average velocity of the water flow. i. Repeat for a 250 ml beaker.

3

Measuring The Speed Of A Clocks Second Hand

ScienceScene.com

a. Select a wall clock with a second hand.

b. As the tip of the second hand rotates around the center of the clock traveling a certain distance (x), in a given time (t).

d. Compute the distance traveled by the outer point of the second.

e. Compute the speed using: v = x / t

1) The tip of the second hand moves in a circle. In order to find the distance traveled, we must find the circumference of that circle. To determine the circumference, we must measure the radius (r) of the circle in meters. The radius is the distance between the center of the clock, and the tip of the second hand. Double that figure to obtain the diameter, and multiply that result by pi (3.14).

2) The total distance traveled would be the number of full revolutions (N) multiplied by the distance traveled or x = (N) x 2r x 3.14. Call this distance x, and record.

Note:

Measuring The Velocity Of A Bouncing Ball.

a. The total distance (x) that the ball traveled is equal to the sum of the heights x1, x2 and x3. The initial height is x1, the final height is (x3) and the average of x1 and x3 is x2. The total distance (x) that the ball traveled is equal to the sum of the heights (x = x1 + x2 + x2 + x3). The heights are most easily measured by bouncing the ball near a wall, using the brick divisions to help in the measurement of the height of the bounce.

b. The time (t) taken for the ball to make two bounces would be measured from the starting point (the release point), to the end point (the top of the second bounce).

c. Compute the average speed using: v = x / t.

d. Collect three sets of data and calculate the average velocity.

e. Repeat for the second ball

Simulation

x1 x2 x2 x3

Total Distance (x) = x1 + x2 + x2 + x3

1

Observers start their stopwatches when they see the flash of light created at the same instant a loud sound occurs. They stop their stopwatches when they hear the sound. Using their data calculate the speed of sound.

BANG!

1.08-sec.331.2-m3

1.06-sec.331.2-m2

1.01-sec.331.2-m1

VelocityTimeDistanceTrial

Speed Of Sound

1. Experimental Speed of Sound = distance / time2. Theoretical Speed of Sound = 330 m/sec. + (.6 m/sec. x Temperature) 3. Temperature = 23.1 ºC4. Calculate Percent of Error

2

Inertia

Applying Small Force Applying Large Force2

What is Inertia?

Answer:

The tendency of matter to remain at rest if it

is at rest or, if moving, the tendency to keep

moving in the same direction unless acted

upon by some outside force.

21

Newton's First Law - Inertia

Objects at rest remain at rest.

A lot of inertia! Very little inertia.

Since the train is so huge, it is difficult to move the train from rest.

Since the baby carriage is so small, it is very easy to move from rest.

Objects in motion remain in motion in a straight line (unless acted upon by an outside force).

A lot of inertia! Very little inertia

Since the train is so huge, it is difficult to stop it once it is moving.

Since the soccer ball is so small, it is very easy to stop it once it is moving.

0

Inertia - Using Your Marbles


24


3


2


1

Click for Inertia Movie


0

Newton’s Second Law

When a force acts on a moving object, it will accelerate in the direction of the force dependent on its mass and the force.

F = m x a

Observing Acceleration - of a Toy Car

0.12

.73-m/s/s

.73-m/s2

0.22-sec

0.16-m/s

(8) a = acceleration between points a = v / t

(7) T = change in time between adjacent velocity t = TB – TA

(6) v = change in adjacent velocity v= v2 – v1

Position B TB = (t2 + t1) / 2

0.38-sec

Position ATA = t1/2

0.16-sec6) Time (when average velocity occurred)

V2

1.25-m/s

V1

1.09-m/s(5) Average velocity v = d / t

0.440.32(4) Average Time

0.110.430.32 Third time trial

0.130.440.31 Second time trial

0.110.430.32 First time trial

0.150-m

t1→ t2 (t2- t1)

0.500-m

t0→ t2

0.350-m

t0→ t1

13

Starting PointAB

t0t1t2

.350-meter.150-meter

.500-meter

Acceleration – A More Complete PictureExcel Worksheet – Push F9 to Reveal Calculations

Observing Forces

Bubble LevelAccelerometer

It moves towards the center of rotationCircular

It moves backwardBackward

It moves forwardForward

It remains constantNone

Direction of FORCE (movement of the accelerometer bubble)Movement of the Car

81

Circular Motion

ID

CP

R4

ID

ID

IDID

ID

ID

ID

CP

CP

CP

CP

R1

R2

R3 CP

CP CP

ID = Inertia direction

Rx = Resultant of Inertia & Center Pull

CP = Center Pull direction

The following diagram helps to explain the circular motion of an object. This motion depends on the object’s inertia, straight line direction, and the force applied by a string pulling the object towards the center of the circle.

0

3

Understanding Forces

2

Pushes and PullsTypes of Forces

ScienceScene

1. 2.3.

4.5.

6.

7.

8

Finding The Forces ActivitiesRead the description in the handout and identify the Forces for each activity

1

0

Finding The Forces Activities

1.2. 3.

4.

5.

6.

7.

1. At Rest 2. At Rest 3. Acceleration 4. At Rest

5. At Rest 7. Accelerating6. At Rest and Accelerating

7

Types of Forces

A force is defined as any push or pull that results in accelerating motion

Circular - When objects move in circles, a force acts with a direction that is toward the center of the circle. We call this direction CENTRIPETAL

Gravitational - All objects attract all other objects with a force called gravitational force.

Electromagnetic - Electric forces act on objects when the object carries a net electric charge or a non-uniform distribution of charge. Magnetic force is also observed around a moving electric charge and act on those charges. Physicists believe that all magnetic forces are produced by moving charges.

Frictional - Frictional forces are often classified as sliding, rolling, static and fluid.Sliding and rolling frictional forces result when solids in contact pass by each other. Static frictional force results when solids are in contact, at rest and when a force or forces are trying to cause them to move with respect to each other. Fluid frictional force results when a solid is moving through a gas or a liquid.

Normal - “Normal” means “perpendicular to”. Whenever an object is placed on a surface, a force acts normal to the surfaces in contact. This causes the supporting surface to sag. Since this sagging is slight, it often goes unnoticed. However, it is always there and the resulting force of the surface attempting to return to its original position is perpendicular to the surface.

Tension - Tension force is the force exerted by a string, spring, beam or other object which is being stretched compressed. The electric forces among the molecules give rise to the force.

Circular

Gravitational

Electromagnetic

Frictional

Normal

Tension

7

Forces in a Collision

1. The diagram shows a child and an adult pushing on each other while holding bathroom scales to measure the forces. Predict how they will move. Explain your prediction. (Does the answer depend on who does the pushing? What if both push at the same time?)

2. Which scale will show the biggest number?

3. Suppose the situation was slightly different than the illustration. For each situation below, predict how the readings on the scales would compare with each other. Explain your predictions.

a. If the adult’s chair was backed up against a wall.b. If the child’s chair was backed up against a wall.c. If both chairs were backed up against a wall.

The Falling Cup

The Affect of Mass on Acceleration

0.86.5000.580.600.570.56

1.14.5000.440.430.440.43

VelocityMeters/sec

Distancemeters

AverageSec.

Trial 3Sec.

Trial 2Sec.

Trial 1Sec.

With

Without

Battery

8

Newton’s Third Law

Every Action Has An Equal And

Opposite Reaction.

f1 = f2

3


2


1


0

Slippery Plastic

Equal and Opposite - Newton’s Third Law

1. Crumple the plastic until it looks very wrinkled

2. Place the slippery plastic on a solid, flat surface.

3. Place the car on top on the slippery plastic.

4. Start the car and observe the car and the slippery plastic.

4

Equal and Opposite, Another Look

1. Place two soda cans on a flat surface approximately 25-cm apart.

2. Place the plastic on top of the soda cans.

3. Place the car on top on the plastic as shown.

4. Start the car and carefully observe the car and the plastic.

23

The Hover CoverBalloon Powered

Materials: Scissors, Plastic lid from a cottage cheese container, Push-pull squirt cap from a bottle of dishwashing liquid, Glue, Round balloon

Instructions:1. Cut a hole 3/4 inch in diameter in the center of the plastic

lid from the cottage cheese container.

2. Center the push-pull squirt cap over the hole and glue it to the lid, with the lid's writing face up. Use enough glue so that no air spaces are left between the plastic surface of the cap and the plastic of the lid. Let the glue dry completely.

3. Blow up a round balloon and slip the opening over the opening on the closed squirt cap.

4. Place the device on a smooth sur face, such as a table top, and lift the squirt-cap opening so that the air escapes from the balloon and your space car will glide effortlessly.

1


0

The Stopwatch

MAKING FORMULAS OUT OF WORDS

CHANGE IN DISTANCESPEED =CHANGE IN TIME

CHANGE IN DISTANCE & DIRECTIONVELOCITY =CHANGE IN TIME

CHANGE IN SPEEDACCELERATION =CHANGE IN TIME

CHANGE IN VELOCITYACCELERATION =CHANGE IN TIME

ΔdSPEED(s) =Δt

ΔsACCELERATION (a) =Δt

ΔvACCELERATION(a) =Δt

Note: to make the equation simple we place “ “ in place of the word “change”

Note: The arrow indicates a change in direction

Δ

7

Δs or ΔdVELOCITY(v) =Δt

We Had A Great Time

(The MAPs Co.) Dr. M. H. Suckley & Mr. P. A. Klozik Email: [email protected].

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Transcript of (The MAPs Co.) Dr. M. H. Suckley & Mr. P. A. Klozik Email: [email protected].