A physics student has designed a winter game. He has a platform 4.6 meters high with a rope tied to a tree at the same height (rope is 4.5 meters long). He swings down from the platform and just at the bottom of the arc he lets go, landing on a sled with another boy already on it sliding at 3 m/sec. in the same direction as the swing. He, his friend and the sled then slide across the snow. The "swinging boy" has a mass of 70 kg, the sled and the "riding boy" have a combined mass of 100 kg and the coefficient of friction between sled and ice is 0.15.
a) how fast is the boy moving just before he lets go of the rope at the bottom of the arc?
b) how fast are the boys and the sled moving after they "collide"?
c) how far will they slide?