Finding Skater's Mass Using Speed

Question

Two ice skaters stand at rest in the center of an ice rink. When they push off against one another the 65 kg skater acquires a speed of 0.64 m/s.

If the speed of the other skater is 0.85 m/s, what is this skater's mass?    

Answer 1

Hi Omar R.!

We can consider this as a collision, and can therefore apply the conservation of momentum to find the mass of the second skater:

m₁v_1o + m₂v_2o = m₁v_1f + m₂v_2f

=> v_1o = v_2o = 0 m*s^-1 because the skaters both start at rest

0 = m₁v_1f + m₂v_2f => m₂ = -m₁v_1f/v_2f

<=> -(65 kg)(0.64 m*s^-1)/(-0.85 m*s^-1)

m₂ = 49 kg

Hope this helps!

Cheers