Halliday, Resnick & Walker — Force and Motion–II: Problem 99

Sliding down a ski slope on your back. Suppose you fall off your skis while skiing down a uniform slope at a moderate speed of 12 m/s. If you are wearing common ski overalls and land on your back, the coefficient of kinetic friction between the overalls and the snow is 0.25. Assume an x axis extends up the slope. What is your velocity along the axis when you hit a tree after sliding for 7.0 s if you are on (a) a blue slope (for beginners) at slope angle 12°, (b) a red slope at angle 18°, and (c) a black slope at angle 25°? (d) If you avoid all obstacles, on which slope will you slide to a stop and how far will that take?