A 100−kg man is skiing across level ground at a speed of 0m/swhen he comes to the small slope 1.8 m higher than ground level shown in the following figure. (a) If the skier coasts up the hill, what is his speed when he reaches the top plateau? Assume friction between the snow and skis is negligible. (b) What is his speed when he reaches the upper level if an 80−N frictional force acts on the skis?

A sked is initially given a shove up a frictionless 23.0o incline. It reaches a maximum vertical height 1.22 m higher than where it started at the bottom. What was its initial speed?

The top of a ski hill sits at an altitude of 2000 m. If you were to "Frenchfry" (go straight down without stopping or turning) down the hill, how fast would he be moving when he reaches an altitude of 600m. Assume the skis are frictionless.

Suppose a car travels 108 km at a speed of 30.0 m/s, and uses 1.90 gallons of gasoline. Only 30% of the gasoline goes into useful work by the force that keeps the car moving at constant speed despite friction. (The energy content of gasoline is 1.30 ✕ 108 J per gallon.) (a) What is the force (in N) exerted to keep the car moving at constant speed? (Enter a number.)686.1N (b) If the required force is directly proportional to speed, how many gallons will be used to drive 108 km at a speed of 28.0 m/s? (Enter a number.)?gallons