A figure skater is spinning on ice with their arms extended. When they pull in their arms, what happens to their rotational kinetic energy? Assume friction and drag are negligible.
D) Can't tell, not enough information
Solution: A. KErot = ½Iω2. And since angular momentum = L = Iω, the formula for rotational kinetic energy can be rewritten as KErot = ½Lω. Angular momentum remains constant while angular velocity increases, so rotational kinetic energy must increase.