Project Observe the motion of an object and describe the motion of that object using previously...

ProjectProjectObserve the motion of an object and Observe the motion of an object and describe the motion of that object using describe the motion of that object using previously learned physics terminology. previously learned physics terminology.

Lesson #53Lesson #53Topic: Impulse and MomentumTopic: Impulse and Momentum

Objectives: Objectives: (After this class I will be able to)(After this class I will be able to)

1.1. Define and describe momentum Define and describe momentum and impulse.and impulse.

2.2. Explain how to change an objects Explain how to change an objects momentum. momentum.

2/6/08

Assignment: Book Ch 9 Read p229 – 232; Complete problems 1-5 Due Tomorrow!

Warm Up: What has more inertia, a roller skate or a Mac truck? What has more momentum a roller skate rolling down a hill, or a Mac truck at rest at the top of the hill?

What has more inertia, a roller skate or a Mac truck?

1.1. Mac TruckMac Truck

2.2. Roller SkateRoller Skate

3.3. SameSame

4.4. Can’t sayCan’t say

Mac

Tru

ck

Rolle

r Ska

te

Sam

e

Can

’t sa

y

0% 0%0%0%

0 of 20

What has more momentum a roller skate rolling down a hill, or a Mac truck

at rest at the top of the hill? 1.1. Mac TruckMac Truck

2.2. Roller SkateRoller Skate

3.3. SameSame

4.4. Can’t sayCan’t say

Mac

Tru

ck

Rolle

r Ska

te

Sam

e

Can

’t sa

y

0% 0%0%0%

0 of 20

MomentumMomentumMomentum is Momentum is inertia in motioninertia in motion..Any mass that is moving has momentum.Any mass that is moving has momentum.The magnitude of an objects momentum is its The magnitude of an objects momentum is its mass times its velocity.mass times its velocity.

Example: Both a Mac truck and a roller skate Example: Both a Mac truck and a roller skate have inertia, but if the truck isn’t moving, then have inertia, but if the truck isn’t moving, then only the roller skate has momentum.only the roller skate has momentum.What are the units of momentum? See if you can What are the units of momentum? See if you can figure it out using the above equation.figure it out using the above equation.

mvp

What are the units of momentum?What are the units of momentum?

Nm

/s

kgm

/s2

kgm

/s

Nm

/s2

0% 0%0%0%

1.1. Nm/sNm/s

2.2. kgm/skgm/s22

3.3. kgm/skgm/s

4.4. Nm/sNm/s22

0 of 20

Momentum Momentum

Momentum is a vector, meaning it has Momentum is a vector, meaning it has magnitude and direction.magnitude and direction.The unit of momentum is a kgm/s.The unit of momentum is a kgm/s.But how does an object gain / lose momentum?But how does an object gain / lose momentum?Lets observe two different equations of Lets observe two different equations of acceleration. acceleration. The definition of acceleration:The definition of acceleration:Newton’s Second Law:Newton’s Second Law:Set these equations equal to one another and Set these equations equal to one another and cross multiply to obtain:cross multiply to obtain:

m

Fa net

t

va

mvFt

What is the momentum of a What is the momentum of a 20000kg truck moving down the 20000kg truck moving down the

interstate at 20m/s?interstate at 20m/s?

4,0

00,0

00kg

m/s

400

,000

kgm

/s

100

0kgm

/s

4,0

00,0

00Nm

/s

0% 0%0%0%

1.1. 4,000,000kgm/s4,000,000kgm/s

2.2. 400,000kgm/s400,000kgm/s

3.3. 1000kgm/s1000kgm/s

4.4. 4,000,000Nm/s4,000,000Nm/s

0 of 20

Impulse Impulse

The right hand side of this equation has a delta. This The right hand side of this equation has a delta. This means “change in” mv or change in momentum.means “change in” mv or change in momentum.

The left hand side of this equation is called The left hand side of this equation is called impulse.impulse.

Impulse is a force exerted over a certain amount of Impulse is a force exerted over a certain amount of time.time.

An impulse will change the momentum of an object.An impulse will change the momentum of an object.

The impulse is the equal to how much the The impulse is the equal to how much the momentum of an object momentum of an object changeschanges when a given when a given force is applied and also has units of kgm/s.force is applied and also has units of kgm/s.

mvFt

A 0.06kg ball is hit with a velocity of 10m/s A 0.06kg ball is hit with a velocity of 10m/s before it impacts the side of a house. What before it impacts the side of a house. What

is the impulse the house exerts on the ball?is the impulse the house exerts on the ball?

.6N

.6kg

m/s

.006

N

.006

kgm

/s

0% 0%0%0%

1.1. .6N.6N

2.2. .6kgm/s.6kgm/s

3.3. .006N.006N

4.4. .006kgm/s.006kgm/s

0 of 20

A 0.06kg ball is hit with a velocity of 10m/s A 0.06kg ball is hit with a velocity of 10m/s before it impacts the side of a house. What before it impacts the side of a house. What

is the force the ball impacts the house with if is the force the ball impacts the house with if

it comes to a stop in .01secondsit comes to a stop in .01seconds

0 of 20 6

N

.000

6kgm

/s 6

0N

60k

gm/s

0% 0%0%0%

1.1. 6N6N

2.2. .0006kgm/s.0006kgm/s

3.3. 60N60N

4.4. 60kgm/s60kgm/s

Basketball InjuriesBasketball InjuriesAs a concerned citizen, you have volunteered to As a concerned citizen, you have volunteered to serve on a committee investigating injuries to serve on a committee investigating injuries to Junior High School students participating in sports Junior High School students participating in sports programs. Currently your committee is programs. Currently your committee is investigating the high incidence of ankle injuries on investigating the high incidence of ankle injuries on the basketball team. You are watching the team the basketball team. You are watching the team practice, looking for activities which can result in practice, looking for activities which can result in large horizontal forces on the ankle. Observing the large horizontal forces on the ankle. Observing the team practice jump shots gives you an idea, so you team practice jump shots gives you an idea, so you try a small calculation. A 40-kg student jumps 1.0 try a small calculation. A 40-kg student jumps 1.0 meters straight up and shoots the 0.80-kg meters straight up and shoots the 0.80-kg basketball at his highest point. From the trajectory basketball at his highest point. From the trajectory of the basketball, you deduce that the ball left his of the basketball, you deduce that the ball left his hand at 30o from the horizontal at 20 m/s. What is hand at 30o from the horizontal at 20 m/s. What is his horizontal velocity when he hits the ground? his horizontal velocity when he hits the ground?

Impulse Examples: Impulse Examples:

Example #1: If I launch a steel ball and a plastic Example #1: If I launch a steel ball and a plastic ball of the same size out of the same launcher ball of the same size out of the same launcher at different times. Which ball will fire farther?at different times. Which ball will fire farther?

Explain in terms of impulse and changing Explain in terms of impulse and changing momentum.momentum.

Which ball will fire farther?Which ball will fire farther?

Ste

el B

all

Pla

stic

Bal

l

Sam

e di

stan

ce

I hav

e no id

ea

0% 0%0%0%

1.1. Steel BallSteel Ball

2.2. Plastic BallPlastic Ball

3.3. Same distanceSame distance

4.4. I have no ideaI have no idea

0 of 20


Since the impulse applied to both balls is Since the impulse applied to both balls is the same then the change in momentum of the same then the change in momentum of each is the same.each is the same.

Then if the mass is greater then the velocity Then if the mass is greater then the velocity must be less and vice versa.must be less and vice versa.


Example #2: A person is at rest on roller skates Example #2: A person is at rest on roller skates and a heavy ball is tossed to them.and a heavy ball is tossed to them.

Explain in terms of impulse and changing Explain in terms of impulse and changing momentum what happens when they catch the momentum what happens when they catch the ball. ball.

A person on skates catches a A person on skates catches a heavy ball. What happens?heavy ball. What happens?

0 of 20 They

roll

backw

ards.

..

They

roll

backw

ards.

..

They

don’

t move

.

0% 0%0%

1.1. They roll backwards They roll backwards with the same velocity with the same velocity as the ball.as the ball.

2.2. They roll backwards They roll backwards with the same with the same momentum as the ball.momentum as the ball.

3.3. They don’t move.They don’t move.


Example #3. A person is at rest on roller Example #3. A person is at rest on roller skates and tosses a heavy ball.skates and tosses a heavy ball.

Explain in terms of impulse and changing Explain in terms of impulse and changing momentum what happens when they toss momentum what happens when they toss the ball.the ball.

A person on skates throws a heavy A person on skates throws a heavy ball. What happens?ball. What happens?

0 of 20 They

roll

backw

ards.

..

They

roll

backw

ards

...

They

don’

t move

.

They

roll

backw

ards

...

0% 0%0%0%

1.1. They roll backwards They roll backwards with the same velocity with the same velocity as the ball.as the ball.

2.2. They roll backwards They roll backwards with more velocity than with more velocity than the ball.the ball.

3.3. They don’t move.They don’t move.

4.4. They roll backwards They roll backwards with less velocity than with less velocity than the ball.the ball.


Example #4: A boxer can throw a punch with all Example #4: A boxer can throw a punch with all of his weight as fast as he can. of his weight as fast as he can.

Explain in terms of impulse and changing Explain in terms of impulse and changing momentum what happens when the opponent momentum what happens when the opponent leans into the punch.leans into the punch.

Explain in terms of impulse and changing Explain in terms of impulse and changing momentum what happens when the opponent momentum what happens when the opponent leans away from the punch.leans away from the punch.

Basketball InjuriesBasketball Injuries

After calculating the horizontal velocity of After calculating the horizontal velocity of the player when returning to the floor, the player when returning to the floor, explain why you think excess jump shots explain why you think excess jump shots might be responsible for the several ankle might be responsible for the several ankle injuries. injuries.

ProjectProject

Collide carts on a dynamics track.Collide carts on a dynamics track.

Collide with varying velocities and mass.Collide with varying velocities and mass.

Observe the collisions and describe the Observe the collisions and describe the motion of the carts before and after motion of the carts before and after collision. collision.

Lesson #54Lesson #54Topic: Conservation of MomentumTopic: Conservation of Momentum


1.1. Describe how the momentum of a system is Describe how the momentum of a system is conserved. conserved.

2.2. Define elastic and inelastic collisions.Define elastic and inelastic collisions.

2/7/07

Warm Up: What impulse must I apply to a 20g golf ball to give it an initial velocity of 30m/s? How much force is applied if the time of impact is 0.2 seconds?

Assignment: Transparency 9-2

What impulse must I apply to a 20g golf ball to give it an initial velocity of 30m/s?

1.1. 600kgm/s600kgm/s

2.2. 0.66kgm/s0.66kgm/s

3.3. 0.60kgm/s0.60kgm/s

4.4. 60kgm/s60kgm/s

0% 0%0%0%

0

20

Conservation of MomentumConservation of Momentum

The amount of momentum a system has The amount of momentum a system has before a collision is equal to the amount of before a collision is equal to the amount of momentum the system has after a momentum the system has after a collision.collision.

ppbeforebefore = p = pafterafter

Remember a “system” is two or more Remember a “system” is two or more objects interacting with one another.objects interacting with one another.

This “interaction” can be in the form of two This “interaction” can be in the form of two different types of collisions.different types of collisions.

Elastic collisions and Inelastic collisions.Elastic collisions and Inelastic collisions.

Elastic CollisionsElastic CollisionsAn elastic collision occurs when two objects An elastic collision occurs when two objects “bounce” off of one another.“bounce” off of one another.

The objects do The objects do notnot stick together. stick together.

Demo: Air Track Carts with rubber bands.Demo: Air Track Carts with rubber bands.

Example: Two billiard balls colliding.Example: Two billiard balls colliding.

The queue ball and the 8 ball both have a mass The queue ball and the 8 ball both have a mass of 100g. The queue ball is struck such that it has of 100g. The queue ball is struck such that it has an initial velocity of 0.5m/s. an initial velocity of 0.5m/s.

aabb vmvmvmvm 22112211

What is the momentum of the What is the momentum of the queue ball before collision?queue ball before collision?

1.1. 0.05kgm/s0.05kgm/s

2.2. 0.1kgm/s0.1kgm/s

3.3. 0kgm/s0kgm/s

4.4. 50kgm/s50kgm/s

0.0

5kgm

/s

0.1

kgm

/s

0kg

m/s

50k

gm/s

0% 0%0%0%

0 of 20

What is the momentum of the What is the momentum of the queue ball after collision?queue ball after collision?

0.0

5kgm

/s

50k

gm/s

0.1

kgm

/s

0kg

m/s

0% 0%0%0%

1.1. 0.05kgm/s0.05kgm/s

2.2. 50kgm/s50kgm/s

3.3. 0.1kgm/s0.1kgm/s

4.4. 0kgm/s0kgm/s

0 of 20

What is the momentum of the 8 ball What is the momentum of the 8 ball before collision?before collision?

0.0

5kgm

/s

50k

gm/s

0.1

kgm

/s

0kg

m/s

0% 0%0%0%

1.1. 0.05kgm/s0.05kgm/s

2.2. 50kgm/s50kgm/s

3.3. 0.1kgm/s0.1kgm/s

4.4. 0kgm/s0kgm/s

0 of 20

What is the What is the velocityvelocity of the 8 ball of the 8 ball after collision?after collision?

0.0

5m/s

0.1

m/s

0.5

m/s

5m

/s

0% 0%0%0%

1.1. 0.05m/s0.05m/s

2.2. 0.1m/s0.1m/s

3.3. 0.5m/s0.5m/s

4.4. 5m/s5m/s

0 of 20

Inelastic CollisionsInelastic CollisionsAn inelastic collision occurs when two objects An inelastic collision occurs when two objects collide and stick together.collide and stick together.The two combined objects have the same The two combined objects have the same velocity and can be treated as one big object.velocity and can be treated as one big object.

Demo: Air track with cork and needle.Demo: Air track with cork and needle.Example: A 100kg football player runs with a Example: A 100kg football player runs with a velocity of 5m/s and collides with a 80kg velocity of 5m/s and collides with a 80kg quarterback that is standing still.quarterback that is standing still.

abb vmmvmvm )( 212211

What is the total momentum of both What is the total momentum of both players before collision?players before collision?

400

kgm

/s

900

kgm

/s

500

kgm

/s

0kg

m/s

0% 0%0%0%

1.1. 400kgm/s400kgm/s

2.2. 900kgm/s900kgm/s

3.3. 500kgm/s500kgm/s

4.4. 0kgm/s0kgm/s

0 of 20

What is the total momentum of both What is the total momentum of both players after the collision?players after the collision?

400

kgm

/s

900

kgm

/s

500

kgm

/s

0kg

m/s

0% 0%0%0%

1.1. 400kgm/s400kgm/s

2.2. 900kgm/s900kgm/s

3.3. 500kgm/s500kgm/s

4.4. 0kgm/s0kgm/s

0 of 20

What is the total What is the total velocityvelocity of both of both players after collision before they players after collision before they

hit the ground?hit the ground?1.1. 0m/s0m/s

2.2. 2.5m/s2.5m/s

3.3. 2.77m/s2.77m/s

4.4. 5m/s5m/s

5.5. 10m/s10m/s

0m

/s

2.5

m/s

2.7

7m/s

5m

/s

10m

/s

0% 0% 0%0%0%

0 of 20

Lesson #55Lesson #55Topic: Lab: MomentumTopic: Lab: Momentum


1.1. Use the idea of conservation of Use the idea of conservation of momentum to predict the velocity momentum to predict the velocity of a dynamics cart.of a dynamics cart.

2/8/07

Assignment: Lab report due Monday. Concept Development 7-1 due Monday.

Warm Up: A cue ball moving at 2m/s hits an 8 ball at rest. What is the velocity of the 8 ball if the cue ball comes to a complete stop?

Lab Task: Use the conservation of momentum to predict the velocity of a dynamics cart and then compare that prediction to a measured value.

A cue ball moving at 2m/s hits an 8 ball at rest. What is the velocity of the 8 ball if the cue ball

comes to a complete stop?

2m

/s

More

than

2m

/s

Les

s th

an 2

m/s

0m

/s

0% 0%0%0%

1.1. 2m/s2m/s

2.2. More than 2m/sMore than 2m/s

3.3. Less than 2m/sLess than 2m/s

4.4. 0m/s0m/s

0 of 20

Momentum Review Momentum Review

1.1. What is momentum?What is momentum?

2.2. What is impulse? What is impulse?

3.3. What will an impulse cause?What will an impulse cause?

4.4. What is an example of an elastic What is an example of an elastic collision?collision?

5.5. What is an example of an inelastic What is an example of an inelastic collision?collision?

6.6. Describe the conservation of momentum.Describe the conservation of momentum.

Momentum ExamplesMomentum Examples

1.1. Two freight cars each with a mass of Two freight cars each with a mass of 3x103x1055kg, collide and stick together. One kg, collide and stick together. One was initially moving at 2.2m/s and the was initially moving at 2.2m/s and the other was at rest. What is their final other was at rest. What is their final speed?speed?

Momentum ExamplesMomentum Examples

2.2. A 35g bullet moving at 400m/s strikes a A 35g bullet moving at 400m/s strikes a 2.5kg steel ball that is at rest. The bullet 2.5kg steel ball that is at rest. The bullet bounces backward after its collision at a bounces backward after its collision at a speed of 5m/s. What is the final velocity speed of 5m/s. What is the final velocity of the ball?of the ball?

A 35g bullet moving at 475m/s strikes a 2.5kg bag A 35g bullet moving at 475m/s strikes a 2.5kg bag of flour that is on ice, at rest. The bullet passes of flour that is on ice, at rest. The bullet passes

through the bag and exits it at 275m/s. How fast is through the bag and exits it at 275m/s. How fast is the bag moving when it exits?the bag moving when it exits?

280

0m/s

462

m/s

6.5

6m/s

2.8

m/s

0% 0%0%0%

1.1. 2800m/s2800m/s

2.2. 462m/s462m/s

3.3. 6.56m/s6.56m/s

4.4. 2.8m/s2.8m/s

A 35g bullet strikes a 5kg stationary piece of A 35g bullet strikes a 5kg stationary piece of lumber and embeds itself in the wood. The piece lumber and embeds itself in the wood. The piece

of lumber and bullet fly off together at 8.6m/s. of lumber and bullet fly off together at 8.6m/s.

What was the original speed of the bullet?What was the original speed of the bullet?

9.8

3m/s

122

9m/s

123

7m/s

1.2

3m/s

0% 0%0%0%

1.1. 9.83m/s9.83m/s

2.2. 1229m/s1229m/s

3.3. 1237m/s1237m/s

4.4. 1.23m/s1.23m/s

A .5kg ball that is traveling at 6m/s (in the positive A .5kg ball that is traveling at 6m/s (in the positive direction) collides head on with a 1kg ball moving direction) collides head on with a 1kg ball moving

in the in the opposite opposite direction at a speed of 12m/s. direction at a speed of 12m/s. The .5kg ball bounces backward at 14m/s after the The .5kg ball bounces backward at 14m/s after the

collision. Find the speed of the second ball after collision. Find the speed of the second ball after collision.collision.

2m

/s

-2m

/s

55m

/s

-55m

/s

0% 0%0%0%

1.1. 2m/s 2m/s

2.2. -2m/s-2m/s

3.3. 55m/s55m/s

4.4. -55m/s-55m/s

ProjectProject

Space Mystery quizSpace Mystery quiz

Observe the collision of two spheres that Observe the collision of two spheres that collide at a 90°.collide at a 90°.

Describe and explain your observations in Describe and explain your observations in terms of momentum, and the conservation terms of momentum, and the conservation of momentum.of momentum.

Hawk vs. GooseHawk vs. GooseYou are a volunteer at the Campus Museum of Natural You are a volunteer at the Campus Museum of Natural History. Because of your interest in the environment and History. Because of your interest in the environment and your physics experience, you have been asked to assist your physics experience, you have been asked to assist in the production of an animated film about the survival in the production of an animated film about the survival of hawks in the wilderness. In the script, a 1.5-kg hawk is of hawks in the wilderness. In the script, a 1.5-kg hawk is hovering in the air so it is stationary with respect to the hovering in the air so it is stationary with respect to the ground when it sees a goose flying below it. The hawk ground when it sees a goose flying below it. The hawk dives straight down. When it strikes the goose and digs dives straight down. When it strikes the goose and digs its claws into the goose's body, it has a speed of 60 its claws into the goose's body, it has a speed of 60 km/hr. The goose, which has a mass of 2.5 kg, was km/hr. The goose, which has a mass of 2.5 kg, was flying north at 30 km/hr just before it was struck by the flying north at 30 km/hr just before it was struck by the hawk and killed instantly. The animators want to know hawk and killed instantly. The animators want to know the velocity (magnitude and direction) of the hawk and the velocity (magnitude and direction) of the hawk and dead goose just after the strike. dead goose just after the strike.

Lesson #56Lesson #56Topic: Momentum in two dimensionsTopic: Momentum in two dimensions


1.1. Describe how momentum is conserved Describe how momentum is conserved in both the x and y direction.in both the x and y direction.

2/13/07

Assignment: Transparency 9-3 due tomorrow!

Warm Up: A 70kg running back runs towards the endzone with a velocity of 4m/s. A 90kg linebacker runs head on into him with a velocity of 2.5m/s just before the goal line. Is there a touchdown or not?

A 70kg running back runs towards the endzone with a velocity of 4m/s. A 90kg linebacker runs head on into him

with a velocity of 2.5m/s just before the goal line. Is there a touchdown or not?

Touch

down! Vaf

ter=

...

Touch

down! Vaf

ter=

...

No g

ood! V

afte

r=0.

34m

/s

No g

ood! V

afte

r=3.

16m

/s

0% 0%0%0%

1.1. Touchdown! VTouchdown! Vafterafter= =

0.34m/s0.34m/s

2.2. Touchdown! VTouchdown! Vafterafter= =

3.16m/s3.16m/s

3.3. No good! No good! VVafterafter=0.34m/s=0.34m/s

4.4. No good! No good! VVafterafter=3.16m/s=3.16m/s0

20

Momentum in two dimensionsMomentum in two dimensionsThe total momentum in the x direction The total momentum in the x direction before and after a collision is equal.before and after a collision is equal.And the total momentum in the y direction And the total momentum in the y direction before and after a collision is equal.before and after a collision is equal.Momentum is a vector.Momentum is a vector.Example: Consider two cars. Car #1 has a Example: Consider two cars. Car #1 has a mass of 2000kg and is traveling north with mass of 2000kg and is traveling north with a velocity of 10m/s. Car #2 has a mass of a velocity of 10m/s. Car #2 has a mass of 1500kg and is traveling east with a velocity 1500kg and is traveling east with a velocity of 15m/s.of 15m/s.

Momentum in two dimensionsMomentum in two dimensions

During the collision the cars stick together During the collision the cars stick together and the total momentum in the x and y and the total momentum in the x and y dimensions remain the same.dimensions remain the same.

1

2

px=m2v2

py=m1v1


Find the total momentum of the cars after Find the total momentum of the cars after the collision.the collision.

12

ptotal=?


Find the direction the cars move after Find the direction the cars move after collision.collision.

12

ptotal=?


Find the velocity of the cars after collision.Find the velocity of the cars after collision.

12

ptotal=?


Example 2: An 8kg bowling ball is rolled toward Example 2: An 8kg bowling ball is rolled toward the south with a velocity of 2m/s.the south with a velocity of 2m/s.

A .5kg wood block is fired towards the west at A .5kg wood block is fired towards the west at 10m/s. It hits the bowling ball and bounces back 10m/s. It hits the bowling ball and bounces back with a velocity of 5m/s toward the east. with a velocity of 5m/s toward the east.

The bowling ball is now moving with a speed The bowling ball is now moving with a speed of ? m/s. of ? m/s.

What was the impulse the block What was the impulse the block exerted on the ball?exerted on the ball?

0 of 20

20% 20% 20%20%20%1.1. .83kgm/s.83kgm/s

2.2. 7.5kgm/s7.5kgm/s

3.3. 146.5kgm/s146.5kgm/s

4.4. 15kgm/s15kgm/s

5.5. I can’t do this I can’t do this problem.problem.

What was the impulse the ball What was the impulse the ball exerted on the block?exerted on the block?

0 of 20

20% 20% 20%20%20%1.1. .83kgm/s.83kgm/s

2.2. 7.5kgm/s7.5kgm/s

3.3. 146.5kgm/s146.5kgm/s

4.4. 15kgm/s15kgm/s

5.5. I can’t do this I can’t do this problem.problem.

What is the ball’s westward What is the ball’s westward component of velocity?component of velocity?

10m

/s

5m

/s

0.9

375m

/s

1.1

25m

/s

25% 25%25%25%1.1. 10m/s10m/s

2.2. 5m/s5m/s

3.3. 0.9375m/s0.9375m/s

4.4. 1.125m/s1.125m/s

0 of 20

What is the new direction of the What is the new direction of the bowling ball?bowling ball?

0% 0% 0%0%0%

1.1. 0.9990.999° S of W° S of W

2.2. 45° S of W45° S of W

3.3. 24.6° S of W24.6° S of W

4.4. 24.6° W of S24.6° W of S

5.5. I cannot do this I cannot do this problem.problem.

0 of 20

Lesson #57Lesson #57Topic: Exam 8 ReviewTopic: Exam 8 Review

2/14/07

Assignment: Exam 8 Review due ! Study for Exam 8.

Warm Up: Observe Newton’s Cradle. When you release 2 balls, why doesn’t one ball bounce out with twice the velocity?


1.1. Practice solving physics problemsPractice solving physics problems

2.2. Complete and check Exam 8 ReviewComplete and check Exam 8 Review

3.3. Plan a tutoring time (if needed)Plan a tutoring time (if needed)

4.4. Complete a bonus problem opportunityComplete a bonus problem opportunity

Observe Newton’s Cradle. When you release 2 balls, why doesn’t one ball bounce out with twice

the velocity?

Bec

ause

mom

entu

m ..

Bec

ause

mom

entu

m i.

..

Bec

ause

ener

gy has

..

Bec

ause

the

balls

kno

w.

0% 0%0%0%

1.1. Because momentum Because momentum is not conserved.is not conserved.

2.2. Because momentum Because momentum is conserved.is conserved.

3.3. Because energy has Because energy has to be conserved as to be conserved as well as momentum.well as momentum.

4.4. Because the balls Because the balls know.know.

0 of 20

Hawk vs. GooseHawk vs. Goose

Hawk wins…Hawk wins…

But what is the magnitude and direction of But what is the magnitude and direction of the velocity of the hawk and goose after the velocity of the hawk and goose after the kill? the kill?

Be able to explain your work and solution Be able to explain your work and solution to the animators of the museum. to the animators of the museum.

If the momentum of an object If the momentum of an object changes and its mass remains changes and its mass remains

constant… constant… 25% 25%25%25%

1.1. Its velocity is Its velocity is changingchanging

2.2. It is acceleratingIt is accelerating

3.3. There is a net There is a net force acting on force acting on the objectthe object

4.4. All of theseAll of these

0 of 5

The momentum change of an The momentum change of an object is equal to the object is equal to the

25% 25%25%25%1.1. The force acting The force acting on iton it

2.2. The impulse The impulse acting on itacting on it

3.3. The change in The change in velocityvelocity

4.4. Mass times the Mass times the force acting on itforce acting on it

0 of 5

Skelly the skater traveling at high speed needs a Skelly the skater traveling at high speed needs a certain amount of force to stop him. More stopping certain amount of force to stop him. More stopping

force will be needed if he hasforce will be needed if he has 25% 25%25%25%

1.1. More massMore mass

2.2. More momentumMore momentum

3.3. Less stopping Less stopping distancedistance

4.4. All of theseAll of these

0of5

The cannonball shot from a cannon with a long The cannonball shot from a cannon with a long barrel will be faster than the same cannon with a barrel will be faster than the same cannon with a short barrel because the cannonball receives a short barrel because the cannonball receives a

greatergreater 25% 25%25%25%

1.1. ForceForce

2.2. ImpulseImpulse

3.3. Both of theseBoth of these

4.4. Neither of theseNeither of these

0

0

5

If the net external force acting on an object If the net external force acting on an object is zero, then the total momentum of the is zero, then the total momentum of the

objectobject 25% 25%25%25%1.1. Is zeroIs zero

2.2. Is equal to its Is equal to its massmass

3.3. Is equal to its Is equal to its mass times mass times velocityvelocity

4.4. Is equal to mass Is equal to mass times accelerationtimes acceleration

0 of 5

1.1. A railroad diesel engine coasting at 12 A railroad diesel engine coasting at 12 km/h runs into a stationary flatcar. The km/h runs into a stationary flatcar. The diesel weighs 3 times as much as the diesel weighs 3 times as much as the flatcar. Assuming the cars couple flatcar. Assuming the cars couple together, how fast are they moving after together, how fast are they moving after collision?collision?

2.2. Reggie Jackson stepped up to the plate Reggie Jackson stepped up to the plate and hit a 0.12 kg fast ball traveling at 36 and hit a 0.12 kg fast ball traveling at 36 m/s, the impact caused the ball to leave m/s, the impact caused the ball to leave his bat with a velocity of 40 m/s in thehis bat with a velocity of 40 m/s in the oppositeopposite direction. If the impact lasted direction. If the impact lasted for 0.004 seconds, with what force did for 0.004 seconds, with what force did Jackson exert on the baseball?Jackson exert on the baseball?

3.3. A ball made of putty has a mass of 3kg and is rolling A ball made of putty has a mass of 3kg and is rolling toward the North with a velocity of 3m/s. It collides with toward the North with a velocity of 3m/s. It collides with another putty ball with the same mass traveling another putty ball with the same mass traveling towards the East with a velocity of 4m/s. towards the East with a velocity of 4m/s.

– Find the velocity of the combined mass after a Find the velocity of the combined mass after a completely inelastic collision.completely inelastic collision.

– Find the direction of the velocity after collision. (How Find the direction of the velocity after collision. (How many degrees North of East?) many degrees North of East?)

BonusBonus

1.1. A gun is fired vertically into a 1.4kg block A gun is fired vertically into a 1.4kg block of wood at rest directly above it. If the of wood at rest directly above it. If the bullet has a mass of 21g and a speed of bullet has a mass of 21g and a speed of 210m/s, how high will the block rise into 210m/s, how high will the block rise into the air after the bullet becomes the air after the bullet becomes embedded into it? (3pts)embedded into it? (3pts)

BonusBonus

2.2. Grady the greedy leprechaun finds a Grady the greedy leprechaun finds a heavy sack of gold out on the center of a heavy sack of gold out on the center of a frozen lake. Grady is able to slide his frozen lake. Grady is able to slide his way out to the gold, but finds that the ice way out to the gold, but finds that the ice is too slick for him to stand, let alone is too slick for him to stand, let alone walk back to shore. Grady is stuck on the walk back to shore. Grady is stuck on the lake with his bag of gold. What must he lake with his bag of gold. What must he do to save himself? (1pt) do to save himself? (1pt)

Project Observe the motion of an object and describe the motion of that object using previously...

Documents

Transcript of Project Observe the motion of an object and describe the motion of that object using previously...