A person sits on a sloped hillside. Is it ever possible to have the static friction force on this person point down the hill? Explain.

Part of a roller-coaster ride involves coasting down an incline and entering a loop 7.30 m in diameter. For safety considerations, the roller coaster's speed at the top of the loop must be such that the force of the seat on a rider is equal in magnitude to the rider's weight. From what height above the bottom of the loop must the roller coaster descend to satisfy this requirement? m

An automobile is going up a grade of 15 with an initial velocity of 30 m/s. The coefficient of static friction between the tires and the road is 0.7. a) What minimum distance does it take to stop the car? b) What minimum distance would it take to stop the car if it were going down the grade?

Engineering problem solving process: Given, Find, Diagram, Solution. You are pulling a sled with some fire wood on it back to your winter cabin at the top of a snowy hill with a 0 = 30° incline. The combined weight of the sled and wood is 10 lb, and the coefficient of friction between the sled and snow is μ = 0.3. You pull on a rope attached to the sled at an angle of p = 20° with respect to the hill surface and accelerates up the hill at ï = 2 ft /s² (a) Calculate the tension T in the rope needed to accelerate at this rate. (b) Suppose the sled is 20 ft up the hill, moving at vo = 4 ft/s, when you accidently slip and lets go of the rope. How long does it take for the sled to slide to the base of the hill? 8