Answer
2.7 grams
Work Step by Step
The ice is already at the melting point. The additional heat causes it to melt. Assume the melted ice stays at 0 degrees C. Half of the original KE goes into melting the ice.
$$\frac{1}{2}(\frac{1}{2}m_{skater}v^2)= Q_{melt}= m_{ice}L$$
$$\frac{1}{2}(\frac{1}{2}(64kg)(7.5m/s)^2)= m_{ice} (3.33\times10^5J/kg) $$
Solve for a mass of 0.0027kg.
