Question

Two ice skaters suddenly push off against one another starting from a stationary position. The 45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60-kg skater acquire relative to the ice?

Answer 1

Answer

Momentum is conserved in this case.

Initial momentum = Final momentum.

Initial momentum = Initial momentum of skater 1 + Initial momentum of skater 2

Initial momentum

$= 45 \times0 + 60 \times 0 \\= 0 kg m/s$

Final momentum

$= 45 \times 0.375 + 60 \times u \\= 16.875 + 60 u$

Here we need to find u.

We have

        $0 = 16.875 + 60 u\\ u = -0.281 m/s$

Speed does the 60-kg skater acquire relative to the ice$= 0.281 m/s$