How to find mass of a hockey puck?

Question

A hockey puck slides along the ice to the right at 8.2 m/s. A hockey stick delivers an impulse of 6.8 Ns, causing the puck to move off to the left at a speed of 2.3 m/s.

 

Find the mass of the hockey puck?

Answer 1

I = Δp = mΔv 

 

I = -6.8 Ns  [the negative sign means the impulse opposes the original direction of motion of the puck]

 

Δv = (-2.3 - 8.2) m/s  [assuming right is positive, left is negative]

 

m = I/Δv = (-6.8 Ns) / [(-2.3 - 8.2) m/s] ≅ 0.65 kg