Momentum and collisions
1.[2p] A 0.20 kg ball arrives at 25 m s⁻¹ and leaves at 20 m s⁻¹ in the opposite direction. What is the magnitude of the impulse, in newton seconds?
A 0.20 kg ball arrives at 25 m s⁻¹ and leaves at 20 m s⁻¹ in the opposite direction. What is the magnitude of the impulse, in newton seconds?
2.[2p] Why does an airbag reduce the force on a driver?
Why does an airbag reduce the force on a driver?
The answer is: It lengthens the time over which the same momentum change happens
The answer is: It lengthens the time over which the same momentum change happens
The answer is: It lengthens the time over which the same momentum change happens
3.[2p] A 1500 kg car at 18 m s⁻¹ hits a stationary 1000 kg car and they lock together. What is their common speed, in metres per second?
A 1500 kg car at 18 m s⁻¹ hits a stationary 1000 kg car and they lock together. What is their common speed, in metres per second?
4.[1p] Momentum is conserved in a perfectly inelastic collision.
Momentum is conserved in a perfectly inelastic collision.
The answer is: True
5.[2p] Which law is momentum conservation a direct consequence of?
Which law is momentum conservation a direct consequence of?
The answer is: Newton's third law, which makes the internal forces of a system cancel in pairs
The answer is: Newton's third law, which makes the internal forces of a system cancel in pairs
The answer is: Newton's third law, which makes the internal forces of a system cancel in pairs
6.[3p] A 3.0 kg body moving at 5.0 m s⁻¹ collides elastically with a stationary 1.0 kg body. What is the final speed of the 1.0 kg body, in metres per second?
A 3.0 kg body moving at 5.0 m s⁻¹ collides elastically with a stationary 1.0 kg body. What is the final speed of the 1.0 kg body, in metres per second?
7.[3p] Which of these are true of an elastic collision in one dimension?
Which of these are true of an elastic collision in one dimension?
Select all that apply
The answer is: The relative speed of separation equals the relative speed of approach, Equal masses exchange velocities when one is initially at rest, A very light body striking a very heavy stationary one rebounds at almost its original speed
8.[3p] A 12 g bullet embeds in a 3.00 kg ballistic pendulum block, which then rises 0.125 m. What was the bullet's speed, in metres per second?
A 12 g bullet embeds in a 3.00 kg ballistic pendulum block, which then rises 0.125 m. What was the bullet's speed, in metres per second?
9.[3p] Match each stage of the ballistic pendulum to the law that applies to it.
Match each stage of the ballistic pendulum to the law that applies to it.
The bullet embedding in the block
The block swinging upward
The whole experiment
Using energy conservation across the impact
momentum first, then energy
momentum conservation, with most kinetic energy lost
gives an answer far too small
mechanical energy conservation
Show the answer
The bullet embedding in the block: momentum conservation, with most kinetic energy lost The block swinging upward: mechanical energy conservation The whole experiment: momentum first, then energy Using energy conservation across the impact: gives an answer far too small