A boy coasts down a hill on a sled, reaching a level surface at the bottom with a speed of 6.4 m/s. If the coefficient of friction between the sled's runners and snow is 0.045 and the boy and sled together weigh 490 N, how far does the sled travel on the level surface before coming to rest?

A Physics proffessor did daredevil stunts in his spare time. His last stunt was to attempt to jump across the river on a motorcycle. The take-off ramp was inclined at 53 degrees the river was 40 m while ,and the far bank wa 15 m lower than the top of the ramp. The river itself was 100 m below ramp. What should his velocity have been at the top of the ramp to have just made it to the edge of the far bank.