A roller coaster starts from rest at its highest point and then descends on its (frictionless) track. Its speed is 38 m/s when it reaches ground level. What was its speed when its height was half that of its starting point

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.

Complete the sentence to describe the law of conservation of energy. the law of conservation of energy states that energy cannot be created

How do cracks affect the rate of weathering?