If the mass is 180g and the volume is 90g what is the density

An open cart is moving along a straight frictionless horizontal track. when rain starts falling vertically into the cart, what happens to the speed of the cart?

This energy transformation diagram represents the energy of a skateboarder moving along a half-pipe. as she skates toward the top of the half-pipe, her original kinetic energy is converted to potential energy and friction. how much of the energy is potential?

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