A car moving at 43 km/h skids 14 m with locked brakes. How far will the car skid with locked brakes at 129 km/h?

Question

we are assuming that energy loss is due only to sliding friction. Answer in units of m.

Answer 1

This is a conservation of energy problem. The skidding is work being done on the car to slow it down. Recall that kinetic energy includes the velocity squared, so if we triple the speed, the kinetic energy increases by nine-fold. If we have nine time the kinetic energy, then we will have to do nine times the work to stop the car.

9 * 14m = 126m