Conservation Laws

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A 200 kilogram car is traveling at 2 meters per second. What does the value “2 meters per second” represent?
1. mass
2. acceleration
3. velocity
4. unknown
Which of the following situations is an example of an elastic collision?
1. Two billiard balls collide and bounce off each other.
2. Two train cars collide and stick together.
3. When a soft piece of clay falls onto the floor, its shape flattens.
4. A glass falls off the table and breaks.
What is the (downward) speed (v2) of the expelled gases?
1. -270 m/sec
2. -0.33 m/sec
3. -21,000 m/sec
4. -7,500 m/sec
Call the initial speed of the sled v2. Which of these variables should be used for the measurement “5 meters per second”?
1. v1
2. m2
3. v3
4. m1
As the speed of a rolling ball is increasing, the increasing speed is accompanied by ____.
1. decreasing momentum
2. increasing momentum
3. increasing inertia
4. both increasing inertia and momentum
What does an object have when moving that it doesn't have when at rest?
1. mass
2. inertia
3. momentum
4. acceleration
The momentum of an object is related to its ____.
1. velocity only
2. mass and force
3. mass and velocity
4. mass only
Which equation would allow you to calculate the speed of the expelled gases?
1. red
2. green
3. purple
4. blue
A 200 kilogram car is traveling at 2 meters per second. Which equation below would allow you to calculate the momentum of the car?
1. PE = mgh
2. F = ma
3. p = mv
4. KE = 1/2mv^2
As a ball falls, the action force is the pull of the Earth's mass on the ball. The reaction force is the ____.
1. nonexistent in this case
2. pull of the ball's mass on the Earth
3. air resistance acting against the ball
4. acceleration of the ball
A baseball player bats a ball with a force of 1000 N. The ball exerts a reaction force against the bat of ____.
1. more than 1000 N, since the bat is more massive than the ball
2. less than 1000 N, since the ball is less massive than the bat
3. 1000 N, since this is an action-reaction interaction
An archer shoots an arrow. Consider the action force to be the bowstring’s push against the arrow. The reaction to this force is the ____.
1. air resistance against the bow
2. weight of the arrow
3. grip of the archer's hand on the bow
4. arrow's push against the bowstring
When two objects hit each other, a(n) ____ occurs.
1. momentum
2. collision
3. joule
4. impulse
A 200 kilogram car is traveling at 2 meters per second. What is the momentum of the car?
1. 0 kg·m/sec
2. 0.01 kg·m/sec
3. 400 kg·m/sec
4. 100 kg·m/sec
The inertia of an object is related to its ____.
1. mass only
2. velocity only
3. mass and force
4. mass and velocity
Two objects, A and B, have the same size and shape, but A is twice as heavy as B. When they are dropped simultaneously from a tower, they reach the ground at the same time, but A has greater ____.
1. speed
2. all of these
3. acceleration
4. momentum
Two objects move separately after colliding. Identify the type of collision.
1. inelastic
2. elastic
Call the (upward) speed of the rocket “v1”. What is the value of “v1”?
1. 150 m/s
2. 800 kg
3. 40,000 kg
4. unknown
While standing on a stationary skateboard, Jolene tosses a heavy ball horizontally toward one end of her skateboard. The skateboard moves. Assuming there is no friction in the system when the ball is tossed, which statement about the momentum of the heavy ball is INCORRECT?
1. The ball’s momentum is equal in size to the momentum of Jolene and her skateboard.
2. The ball’s momentum has increased because Jolene has tossed it.
3. The directions of the ball’s momentum and Jolene’s momentum are the same.
4. The ball’s momentum plus the momentum of Jolene and her skateboard equals zero.
Call the mass of the rocket “m1”. What is the value of “m1”?
1. unknown
2. 150 m/s
3. 40,000 kg
4. 800 kg
Even though every action force has an equal but opposite reaction force, they do not cancel one another and motion may still occur because the action and reaction forces ____.
1. have different magnitudes
2. are applied to the same object
3. are applied to different objects
4. have equal magnitudes
Two objects stick together and move with the same velocity after colliding. Identify the type of collision.
1. elastic
2. inelastic
Call the mass of the sled m2. Which of these variables should be used for the measurement “40 kilograms”?
1. v3
2. v1
3. m1 + m2
4. m1
A rocket can fly into space because ____.
1. as the fuel burns, the rocket’s mass decreases reducing the force of gravity on the rocket
2. the exhaust gases push against the ground and the ground, in turn, pushes the rocket
3. the launch pad absorbs momentum that it imparts to the rocket
4. the rocket pushes on exhaust gases and the exhaust gases push back on the rocket
Call the initial speed of the boy v1. Which of these variables should be used for the initial speed of the stationary sled?
1. v3 = 0
2. v2 = 0
3. unknown
4. v1 = 0
Call the (downward) speed of the gases “v2”. What is the value of “v2”?
1. unknown
2. 150 m/s
3. 40,000 kg
4. 800 kg
Call the mass of the boy m1. Which of these variables should be used for the measurement “10 kilograms”?
1. v3
2. m1 + m2
3. m2
4. v1
Which of the equations is correctly solved for the final speed of the boy and sled together?
1. red
2. green
3. purple
4. blue
A 200 kilogram car is traveling at 2 meters per second. What does the value “200 kilograms” represent?
1. unknown
2. velocity
3. acceleration
4. mass
To calculate momentum ____.
1. multiply the mass of an object by its inertia
2. add the mass of an object to its velocity
3. add the mass of an object to its inertia
4. multiply the mass of an object by its velocity
What is the final speed of the boy and sled together?
1. 5 m/sec
2. 10 m/sec
3. 2 m/sec
4. 4 m/sec
An ice skater speeds up from an initial velocity of 3 m/s to a velocity of 5 m/s. The momentum of the skater ____.
1. becomes zero
2. increases
3. remains the same
4. decreases

Conservation Laws - Momentum

Review Questions