Write down everything that you remember about momentum.

Warm-Up: January 5, 2015

First retake this Wednesday, 2:45.◦ AP Physics: Kinematics◦ AP Calculus: Chapter 1◦ Adv. Math I: Chapter 1

Missing/incomplete homework, test corrections and signed test must be turned in tomorrow in class.◦ A copy of the test will only be printed for you if

everything is complete.

Test Retakes

MomentumAP Physics 1

Linear Momentum and Force

OpenStax section 8.1AP Physics 1

Linear Momentum

vmp

We use the symbol p for “progress”

a) Calculate the momentum of a 110. kg football player running at 8.00 m/s.

b) Calculate the momentum of a 0.410 kg football that has a speed of 25.0 m/s.

c) What is the ratio of the player’s momentum to the ball’s momentum?

You-Try 8.1

a) Calculate the momentum of a 110. kg football player running at 8.00 m/s.

b) Calculate the momentum of a 0.410 kg football that has a speed of 25.0 m/s.

c) What is the ratio of the player’s momentum to the ball’s momentum?

c) 85.9

Remember Newton’s Second Law?

amF

net

t

vmF

net

t

vmF

net

t

pF

net

The net external force equals the change in momentum of the system divided by the time over which it changes.

This works whether or not mass is constant.

Newton’s Second Law

t

pF

net

During the 2007 French Open, Venus Williams set a record for the fastest serve in a premier women’s match, reaching a speed of 58 m/s (130 mph). What is the average force exerted on the 0.057 kg tennis ball by Venus Williams’ racquet, assuming the ball’s speed just after impact is 58 m/s, that the initial horizontal component of the velocity before impact is negligible, and that the ball remained in contact with the racquet for 5.0 ms?

You-Try 8.2

During the 2007 French Open, Venus Williams set a record for the fastest serve in a premier women’s match, reaching a speed of 58 m/s (130 mph). What is the average force exerted on the 0.057 kg tennis ball by Venus Williams’ racquet, assuming the ball’s speed just after impact is 58 m/s, that the initial horizontal component of the velocity before impact is negligible, and that the ball remained in contact with the racquet for 5.0 ms?

660 N

An object with a small mass and an object with a large mass have the same momentum. Which one has the larger kinetic energy?

Think-Pair-Share

a) Calculate the momentum of a 2000. kg elephant charging a hunter with a speed of 7.50 m/s.

b) Compare the elephant’s momentum with the momentum of a 0.0400 kg tranquilizer dart fired at a speed of 600 m/s.

c) What is the momentum of the 90.0 kg hunter running at 7.40 m/s after missing the elephant?

You-Try 1

a) Calculate the momentum of a 2000. kg elephant charging a hunter with a speed of 7.50 m/s.

b) Compare the elephant’s momentum with the momentum of a 0.0400 kg tranquilizer dart fired at a speed of 600 m/s.

c) What is the momentum of the 90.0 kg hunter running at 7.40 m/s after missing the elephant?

Read OpenStax textbook Chapter 8 (online)

Assignment

ImpulseOpenStax section 8.2

AP Physics 1

There are two identical blocks sitting on the same surface. One experiences a small net force, while the other experiences a large net force. Both blocks experience the same change in momentum.

What can you conclude?

Think-Pair-Share

This is the same as the change in momentum.

Impulse

tFJ net

pJ

Two identical billiard balls strike a rigid wall with the same speed, and are reflected without any change in speed. The first ball strikes perpendicular to the wall. The second strikes the wall at an angle 30° from the perpendicular, and bounces off at an angle of 30° from perpendicular to the wall.

a) Determine the direction of the force on the wall due to each ball.

b) Calculate the ratio of the magnitudes of the impulses on the two balls by the wall.

You-Try 8.3

Two identical billiard balls strike a rigid wall with the same speed, and are reflected without any change in speed. The first ball strikes perpendicular to the wall. The second strikes the wall at an angle 30° from the perpendicular, and bounces off at an angle of 30° from perpendicular to the wall.

a) Determine the direction of the force on the wall due to each ball.

b) Calculate the ratio of the magnitudes of the impulses on the two balls by the wall.

Warm-Up: January 6, 2015

Two identical billiard balls strike a rigid wall with the same speed, and are reflected without any change in speed. The first ball strikes perpendicular to the wall. The second strikes the wall at an angle 30° from the perpendicular, and bounces off at an angle of 30° from perpendicular to the wall.

a) Determine the direction of the force on the wall due to each ball.

b) Calculate the ratio of the magnitudes of the impulses on the two balls by the wall.

A 75.0 kg person is riding in a car moving at 20.0 m/s when the car runs into a bridge abutment.

a) Calculate the average force on the person if he is stopped by a padded dashboard that compresses an average of 1.00 cm.

b) Calculate the average force on the person if he is stopped by an air bag that compresses an average of 15.0 cm.

Warm-Up: January 7, 2015

A 75.0 kg person is riding in a car moving at 20.0 m/s when the car runs into a bridge abutment.

a) Calculate the average force on the person if he is stopped by a padded dashboard that compresses an average of 1.00 cm.

b) Calculate the average force on the person if he is stopped by an air bag that compresses an average of 15.0 cm.

Saturday, March 21, 2015 at 9 am and repeated on Sunday, March 22, 2015 at 9 am

University of San Diego Free 2 hour exam Contains AP Chemistry material

Chemistry Olympiad

Cars used to be made with rigid frames, but now are made with frames that can crumple in the event of a collision. Why is this advantageous?

Think-Pair-Share

Conservation of MomentumOpenStax section 8.3

AP Physics 1

An isolated system is defined to be one for which the net external force is zero.

In an isolated system, momentum is conserved.

Isolated Systems

0net F

The total momentum of an isolated system is conserved.◦ It may be transferred between objects in the

system.

Conservation of Momentum

constant

0

total

p

p

Can momentum be conserved for a system if there are external forces acting on the system?

If so, under what conditions? If not, why not?

Think-Pair-Share

Can objects in a system have momentum while the momentum of the system is zero? Explain your answer.

Think-Pair-Share

Train cars are coupled together by being bumped into one another. Suppose two loaded train cars are moving toward one another, the first having a mass of 150,000 kg and a velocity of 0.300 m/s, and the second having a mass of 110,000 kg and a velocity of -0.120 m/s. What is their final velocity?

You-Try 23

Train cars are coupled together by being bumped into one another. Suppose two loaded train cars are moving toward one another, the first having a mass of 150,000 kg and a velocity of 0.300 m/s, and the second having a mass of 110,000 kg and a velocity of -0.120 m/s. What is their final velocity?

A 1.80 kg falcon catches a 0.650 kg dove from behind in midair. What is their final velocity after impact if the falcon’s velocity is initially 28.0 m/s and the dove’s velocity is 7.00 m/s in the same direction?

Warm-Up: January 8, 2015

A 1.80 kg falcon catches a 0.650 kg dove from behind in midair. What is their final velocity after impact if the falcon’s velocity is initially 28.0 m/s and the dove’s velocity is 7.00 m/s in the same direction?

Elastic Collisions in One Dimension

OpenStax Section 8.4AP Physics 1

Internal kinetic energy is the sum of the kinetic energies of the objects in a system.

An elastic collision is one that conserves internal kinetic energy.

Definitions

The only truly elastic collisions are microscopic (such as electrons striking nuclei).

Macroscopic collisions may be very nearly elastic.◦ We often approximate these as elastic.

Elastic Collisions

Calculate the velocities of two objects following an elastic collision, given that:

Example 8.4

(exact) 0

m/s 00.4

kg 500.3

kg 500.0

,2

,1

2

1

i

i

v

v

m

m

Inelastic Collisions in One Dimension

OpenStax section 8.5AP Physics 1

An inelastic collision is one in which the internal kinetic energy changes (is not conserved).

A perfectly inelastic collision is when the colliding objects stick together and have the same final velocity.

Inelastic Collisions

a) Find the recoil velocity of a 70.0 kg ice hockey goalie, originally at rest, who catches a 0.150 kg hockey puck slapped at him at a velocity of 35.0 m/s. Assume friction with the ice is negligible.

b) What percent of the kinetic energy is lost during the collision?

You-Try 8.5

a) Find the recoil velocity of a 70.0 kg ice hockey goalie, originally at rest, who catches a 0.150 kg hockey puck slapped at him at a velocity of 35.0 m/s. Assume friction with the ice is negligible.

b) What percent of the kinetic energy is lost during the collision?

A battleship that is 6.00x107 kg and is originally at rest fires a 1100 kg artillery shell horizontally with a velocity of 575 m/s.

a) If the shell is fired straight aft (toward the rear of the ship), there will be negligible friction opposing the ship’s recoil. Calculate its recoil velocity.

b) Calculate the increase in internal kinetic energy (for the ship and shell).

You-Try 34

A battleship that is 6.00x107 kg and is originally at rest fires a 1100 kg artillery shell horizontally with a velocity of 575 m/s.

a) If the shell is fired straight aft (toward the rear of the ship), there will be negligible friction opposing the ship’s recoil. Calculate its recoil velocity.

b) Calculate the increase in internal kinetic energy (for the ship and shell).

Read OpenStax Chapter 8

Assignment

Two identical balls are rolling towards each other at 2.00 m/s. They collide head-on, and each roll away in the direction they came at 1.8 m/s. Is this a violation of the conservation of momentum? Why or why not?

Warm-Up: January 12, 2015

You have the rest of class to work on the momentum review from Friday.

Momentum Review

With the student next to you (your think-pair-share partner), write 3 multiple choice and/or multiple select test questions.

We will go over the momentum review questions tomorrow and Thursday.

January 13, 2015

Always, sometimes, or never:1) Momentum is conserved in a collision.2) Momentum is conserved in an elastic collision.3) Momentum is conserved in an inelastic

collision.4) Momentum is conserved for closed, isolated

systems.5) Momentum is conserved when no forces are

acting on the system.6) Momentum is conserved when at least one

force is acting on the system.

Warm-Up: January 14, 2015

If you did not turn them in yesterday, turn them in now.

MC Questions

Momentum Review

Two penguins, both of mass 20.0 kg, are sliding across frictionless ice at a constant 1.20 m/s. They collide and stick together, and continue to travel at 0.849 m/s.

Is this a violation of the law of conservation of momentum. Why or why not?

Warm-Up: January 15, 2015

3 spots remaining for AMC 12

American Mathematics Competition

Momentum Review

Clear everything off of your desk except for your pencils, erasers, and calculator.

If you appear to be talking, looking at anyone else’s test, allowing anyone else to look at your test, or using any unauthorized aide, you will receive a zero.

When finished, turn in your test to Mr. Szwast and study for your final exam.

January 16, 2015

14)c) The internal kinetic energy of the system is zero.

Test Erratum

Two cars are driving towards each other. One has a mass of 5000 kg and a speed of 35 mph. The other has a mass of 7000 kg and a speed of 40 mph. They collide and stick together. What is the speed of the cars after they collide?

Warm-Up: January 20, 2015

20 questions 2.5 weight in gradebook (50 points)

Retake/make-up available Thursday at noon.

Momentum Test

Min = 4 Q1 = 7.5 Med = 11 Q3 = 14 Max = 20

Mean = 10.88 Standard Dev. = 4.07

Mode = 10

Momentum Test Statistics

1 A 11 D2 C 12 C3 B 13 D4 D 14 D5 B 15 C6 D 16 E7 D 17 B8 A 18 AB9 C 19 AD

10 D 20 BD

Momentum Test Answers

Momentum Questions?

Jocelyn’s Presentation