Aroller coaster car rapidly picks up speed as it rolls down a hill. as it starts down the hill, its speed is 4 m/s. but 3 seconds later, at the bottom of the hill, its speed is 22 m/s. what is its average acceleration?

Awind turbine is rotating counterclockwise at 0.5 rev/s and slows to a stop in 10 s. its blades are 20 m in length. (a) what is the angular acceleration of the turbine? (b) what is the centripetal acceleration of the tip of the blades at t=0s? (c) what is the magnitude and direction of the total linear acceleration of the tip of the blades at t=0s?

Which of the following forces require physical contact? tension air resistance friction magnetic force applied force

2) why do satelites not fall while revolving around the earth?