Question: A 4.5 kg box slides down a 4.8-m -high frictionless hill, starting from rest, across a 2.0-m -wide horizontal surface, then hits a horizontal spring with spring constant 520 N/m . The other end of the spring is anchored against a wall. The ground under the spring is frictionless, but the 2.0-m-long horizontal surface is rough. The coefficient of kinetic friction of the box on this surface is 0.24.
Part A: What is the speed of the box just before reaching the rough surface? Express your answer to two significant figures and include the appropriate units.
Part B: What is the speed of the box just before hitting the spring? Express your answer to two significant figures and include the appropriate units.
Part C: How far is the spring compressed? Express your answer to two significant figures and include the appropriate units.
Part D: Including the first crossing, how many complete trips will the box make across the rough surface before coming to rest?