Question

Two hockey pucks with mass 0.1 kg slide across the ice and collide. Before the collision, puck 1 is going 8 m/s to the east and puck 2 is going 7 m/s to the west. After the collision, puck 1 is going 7 m/s to the west. What is the velocity of puck 2?

Answer 1

Velocity 8 m/s

Step-by-step explanation:

Given:

m₁ = m₂ = 0.1 kg

v₁ = 8 m/s

v₂ = - 7 m/s

v₁' = - 7 m/s

____________

v₂' - ?

Law of conservation of momentum:

m₁·v₁ + m₂·v₂ = m₁·v₁' + m₂·v₂'

m₁·8 - m₂·7 = - m₁·7 + m₂·v₂'

m₁ = m₂

8 - 7 = - 7 + v₂'

v₂' = 8 m/s = v₁

This phenomenon is called "velocity exchange".