2014-15 SHC Physics
MTM
Name: _________________________________
Physical Quantity Description Symbol Units Equation
MTM 1 Bar Charts: I can draw and analyze momentum bar charts for 1-D interactions (IF or IFF charts).
MTM 2 Explain: I can explain a situation in words using momentum concepts.
MTM 3 Conservation: I can use the law of conservation of momentum to solve collision problems.
MTM 4 Impulse: I can use the relationship between the force applied to an object and the time duration of the force to calculate the impulse delivered to that object
NG 1 Key Question:
NG 2 Investigation:
NG 3 Analysis:
NG 4 Model:
NG 5 Explaining:
Asking Questions and Defining Problems
Planning and Carrying Out Investigations
Analyzing and Interpreting Data
Developing and Using Models
Constructing Explanations, Designing Solutions, Engaging in Argument from Evidence

Sketch
Bar Chart
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Mass of green cart is doubled to 2 kg. The green and 1 kg blue carts approach each other, stick together and stop.
Explosion 1: A 1 kg green cart and a 1 kg blue cart both start at rest, and explode apart in different directions.
Explosion 2: The green cart mass is doubled to 2 kg and they are exploded again.
Where should we start them so that they hit the blocks at the same time?
Each cart is 16 cm long.
Sketch
Bar Chart
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A 2-kg red cart moving right at 2 m/s collides inelastically with a 1-kg blue cart moving left at 4 m/s.
Sketch
Bar Chart
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Conservation of
Momentum
EQUATION:
A 2-kg red cart moving right at 3 m/s collides inelastically with a 1-kg blue cart moving left at 3 m/s.
Sketch
Bar Chart
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AFTER
Conservation of
Momentum
EQUATION:

A 1-kg red cart moving right at 5 m/s collides elastically with a 3-kg blue cart moving right at 1 m/s. (Hint: Drag the blue car to the left to leave space before starting.)
Sketch
Bar Chart
BEFORE
Sketch
Bar Chart
AFTER
Conservation of
Momentum
EQUATION:
A 2-kg red cart moving right at 3 m/s collides elastically with a 1-kg blue cart moving left at 3 m/s.
Sketch
Bar Chart
BEFORE
Sketch
Bar Chart
AFTER
Conservation of
Momentum
EQUATION:

A 1-kg red cart and a 2-kg blue cart are exploded apart. Sketch
Bar Chart
BEFORE
Sketch
Bar Chart
AFTER
Conservation of
Momentum
EQUATION:
1.
An astronaut of mass 80.0 kg carries an empty oxygen tank of mass 10.0 kg. By pushing the tank away with a speed of 2.0 m/s, the astronaut recoils in the opposite direction. Find the speed with which the astronaut moves off into space.

2.
A 2.0 kg melon is balanced on a circus performer's head. An archer shoots a 50.0 g arrow at the melon with a speed of 30 m/s. The arrow passes through the melon and emerges with a speed of 18 m/s. Find the speed of the melon as it flies off the performer's head.
3.
A 50.0 kg cart is moving across a frictionless floor at 2.0 m/s. A 70.0 kg boy, riding in the cart, jumps off so that he hits the floor with zero velocity. What was the velocity of the cart after the boy jumped?
4.
In a railroad yard, a train is being assembled. An empty boxcar, coasting at 3.0 m/s, strikes a loaded car that is stationary, and the cars couple together. Each of the boxcars has a mass of 9000 kg when empty, and the loaded car contains 55,000 kg of lumber. Find the speed of the coupled boxcars.

1.
If you throw a ball horizontally while standing on roller skates, you roll backwards. Will you roll backwards if you go through the motions of throwing the ball, but hold on to it instead? Explain your reasoning.
2.
Which has the greater change in momentum, a 50 gram clay ball that strikes a wall at 1 m/s and sticks or a 50 gram superball that strikes a wall at 1 m/s and bounces away from the wall at 0.8 m/s? Explain your
reasoning.
3.
Two objects, A & B, have identical velocities. Object A has 3 times the mass of object B. Find the value of the ratio of momentum A to momentum B. Justify your answer.
4.
Two objects, C & D, have the same momentum. Object C has ½ the mass of object D. Find the value of the ratio of velocity C to velocity D. Justify your answer
5.
One way of measuring the muzzle velocity of a bullet is to fire it h orizontally into a massive block of wood placed on a cart. Assuming no friction, we then measure the velocity with which the wood containing the bullet and cart begin to move. In one experiment the bullet had a mass of 50 g and the wood and its cart had a combined mass of 10 kg. After the shot, the cart, wood, and bullet moved at a constant speed, traveling 0.80 m in 0.40 s. From this data determine the original speed of the bullet. (That is, the speed of the bullet right before it hits the cart.)

6.
A raft of mass 180 kg carries two swimmers with masses 50 kg and 80 kg. The raft is initially floating at rest. The two swimmers simultaneously dive off opposite ends of the raft, each with a horizontal velocity of 3 m/s. With what velocity and in what direction does the raft start to move?
7.
Jack nervously entered the Skate-O-Rama building for his class reunion. The gaudily decorated room is filled with people and chatter, drinking and laughing. But then . . . across the room, Jack sees Anne--his long lost love. Their eyes lock, and for a moment time stands still. The powerful attraction is still there.
They glide toward one another, first slowly but then faster and faster until 80 kg Jack is traveling 3.2 m/s toward 60 kg Anne who approaches him at 3.8 m/s. They collide in a totally inelastic embrace. What is their final speed and direction after the collision?

Design three mini-experiments to determine the factors that affect how far a marshmallow(s) will travel. Write the following things up on your blog.
NG 1 Key Question: Asking Questions and Defining Problems
For each experiment list the KEY QUESTION you are trying to answer. Also list the IV, DV and CV for each of the three experiments. There should be THREE sets.
NG 2 Investigation: Planning and Carrying Out Investigations
Write a step-by-step procedure for each of the three experiments. Be sure to state how exactly you will measure each variable, and how you will be sure to keep your controlled variables constant.
NG 3 Analysis: Analyzing and Interpreting Data
Create a date table for each experiment. Analyze your data either with a verbal statement of the results as a whole, or mathematically if appropriate.
NG 4 Model: Developing and Using Models
Based on all of your data collected, write a statement that shows what you should do if you wanted your marshmallow to shoot the farthest possible.
NG 5 Explaining: Constructing Explanations, Designing Solutions, Engaging in Argument from Evidence
Support your statement from NG 4 with specific evidence from your experiments.
Water Balloon toss
Impulse – bowling ball taps
Demos: egg and sheet
Car crash video analysis:
Reducing Risk in a crash - https://www.youtube.com/watch?v=qSydxQWjj4I
Between Old and New Cars - https://www.youtube.com/watch?v=3l4YBf2tjag (more crumple zone)

Watch the following videos of car crashes and read the descriptions. http://regentsprep.org/regents/physics/phys01/accident/
Based on the videos and prior discussion list 3 things you can do to increase your safety in a car crash. State
WHAT you need to do and the PHYSICS principle that guided your decision.
Answer the following questions:
1. A Monster Truck and a VW Beetle traveling at equal speeds have a head-on collision. a. Which vehicle will experience the greater force of impact? Justify your answer. b. Which vehicle will experience the greater change in momentum? Justify your answer. c. Which vehicle will have more damage done? Justify your answer
2. Discuss the following in terms of impulse and momentum:
Why are there airbags in cars?
Why are nylon ropes, which stretch considerably under stress, favored by mountain climbers?

c. a.
A tennis player returns a 30 m/s serve straight back at 25 m/s, after making con tact with the ball for 0.5 s. If the ball has a mass of 0.2 kg, what is the force she exerted on the ball?
1. While being thrown, a net force of 132 N acts on a baseball (mass = 140 g) for a period of 4.5 x 10 -2 sec.
If the initial speed of the baseball is v = 0 m/s, what will its speed be when it leaves the pitcher's hand?
When the batter hits the ball, a net force of 1150 N, opposite to the direction of the ball's initial motion, acts on the ball for 9.0 x 10 -3 s during the hit. What is the final velocity of the ball?
How large is the force the ball exerts on the bat? Explain.

2. A rocket, weighing 4.36 x 10 4 N, has an engine that provides an upward force of 1.2 x 10 5 N. It reaches a maximum speed of 860 m/s. Ignore any air resistance. a.
Describe the motion of the rocket and draw a motion map vertically in the margin. b.
Draw a free body diagram for the rocket. c.
For how much time must the engine burn during the launch in order to reach this speed?
3. A golf ball that weighs 0.45 N is dropped from a height of 1.0 m. Assume that the golf ball has a perfectly elastic collision with the floor, bouncing all the way up to its original height. a.
Draw a free body diagram of the ball as it falls. b.
Vertically in the margin, construct a motion map for the golf ball from the time it is dropped until it reaches its highest point of rebound. c.
Draw a free body diagram of the ball as it rises during the rebound. d.
The ball is moving at 4.4 m/s as it enters the floor. Since the collision is perfectly elastic, the ball leaves the floor on the way up also with a speed of 4.4 m/s. Suppose that the golf ball was in contact with the floor for 4.0 x 10 -4 s. What was the average force on the ball while it was in contact with the floor?

Rukle
Think about how the concepts of momentum and impulse inform our decisions on safety devices in cars. You will be working with your group to design, build, test and evaluate a Collision Safety Device (in the form of a landing pad) to protect a raw egg in a collision with the floor. You will have 20 minutes to build your device. You may not pre-test with the egg. There will be 4 rounds of drops, at 1.0 m, 1.5 m, 2.0 m, and 2.5 m.
Materials:

10 sheets of copier paper
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1 meter of masking tape
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1 pair of scissors
Rules:
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You may use less, but no more, than 10 sheets of paper. In the event of a tie, the device using less sheets of paper will be declared the winner.

Collision Safety Devices must be freestanding. You cannot hold them up or tape them to the floor or another object.
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Nothing may be attached to the egg.
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Scissors may not be included in the device.
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Eggs will be inspected before and after each drop and must not show any cracks. Eggs that survive the impact but then roll off and break are eliminated. Teams that break their egg on accident are eliminated.
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Photo of device.
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A paragraph explaining your design rationale and WHY you think it will save the egg (in physics language!).
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A photo or video of the egg hitting the device.
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An explanation of how your device fared, and what improvements you would make if given the challenge again.
Use ALL of your knowledge to solve for AS MANY THINGS as you can in the following problems.
1.
Julio (an 80 kg ice skating champion) and Grace are skating together on a rink (whose circumference is 100 meters) at 3 m/s. Julio keeps asking Grace how much she weighs.
Annoyed, Grace pushes away from Julio so that she speeds up to 4 m/s and he slows down to 2.25 m/s, still moving in the same direction. The push lasts for 0.20 seconds. Friction, in the physics sense, is negligible in this drama.

2.
A 5000 kg truck rear-ends a 1200 kg car when the car was moving at 13 m/s. During the
0.15 second collision, the truck slows down from 14 m/s to 13.5 m/s. The road is dangerously slick, but not completely frictionless (μ= 0.1 between the cars and the road).
http://www.physicsclassroom.com/class/momentum