Question: A streetcar is freely coasting (no friction) around a large circular track. It is then switched to a small circular track. When coasting on the smaller circle its speed is:
w = v/r
KE = 1/2mv2
My teacher said the normal force from the track on the train doing work as the train switches from the larger to the smaller circle and something about how the conservation of momentum is not valid in this situation. And when I looked this question up online, they saw that energy is conserved. However, I'm still confused on how to solve this problem and what the answer is (I think it's unchanged?).