Conservation of momentum in collisions and explosions

Question 1

A 5 kg toy cannon at rest fires a 0.05 kg ball forwards at 500 m/s. What is the recoil speed of the cannon, in m/s?

Answer m/s

Question 2

In a car crash test, momentum is conserved but kinetic energy is not. Where does the kinetic energy go?

• A. into deforming the cars, heating them and sound
• B. it is destroyed
• C. into extra momentum
• D. into the cars' nuclear store

Question 3

A 2 kg trolley moving at 12 m/s hits a stationary 1 kg trolley. They stick together. What is their velocity just after the collision, in m/s? (Give 2 decimal places.)

Answer m/s

Question 4

A 2 kg toy cannon at rest fires a 0.05 kg ball forwards at 300 m/s. What is the recoil speed of the cannon, in m/s?

Answer m/s

Question 5

In a car crash test, momentum is conserved but kinetic energy is not. Where does the kinetic energy go?

• A. into the cars' nuclear store
• B. into deforming the cars, heating them and sound
• C. it is destroyed
• D. into extra momentum

Question 6

A 1 kg trolley moving at 12 m/s hits a stationary 1 kg trolley. They stick together. What is their velocity just after the collision, in m/s? (Give 2 decimal places.)

Answer m/s

Question 7

A 2 kg toy cannon at rest fires a 0.02 kg ball forwards at 500 m/s. What is the recoil speed of the cannon, in m/s?

Answer m/s

Question 8

Why does a rocket in space accelerate forwards when it pushes exhaust gases backwards?

• A. It pushes against the air
• B. Gravity pushes it
• C. The gases gain backward momentum, so the rocket gains equal forward momentum
• D. Momentum is not conserved in space

Question 9

A 1 kg trolley moving at 2 m/s hits a stationary 1 kg trolley. They stick together. What is their velocity just after the collision, in m/s? (Give 2 decimal places.)

Answer m/s

Question 10

A 5 kg toy cannon at rest fires a 0.02 kg ball forwards at 400 m/s. What is the recoil speed of the cannon, in m/s?

Answer m/s

Question 11

In which situation is momentum conserved?

• A. only when objects are stationary
• B. in a closed system with no external forces
• C. only in elastic collisions
• D. never

Question 12

A 1200 kg car moving at 6 m/s hits a stationary 1000 kg car. They lock together. What is their velocity just after the collision, in m/s? (Give 2 decimal places.)

Answer m/s

Question 13

A 2 kg toy cannon at rest fires a 0.02 kg ball forwards at 400 m/s. What is the recoil speed of the cannon, in m/s?

Answer m/s

Question 14

In which situation is momentum conserved?

• A. in a closed system with no external forces
• B. never
• C. only in elastic collisions
• D. only when objects are stationary

Question 15

A 1 kg trolley moving at 4 m/s hits a stationary 1 kg trolley. They stick together. What is their velocity just after the collision, in m/s? (Give 2 decimal places.)

Answer m/s

Question 16

A 2 kg toy cannon at rest fires a 0.05 kg ball forwards at 500 m/s. What is the recoil speed of the cannon, in m/s?

Answer m/s