What is the difference between average and instantaneous acceleration? When would each o these be useful?

An automobile steering wheel is shown. what is the ideal mechanical advantage? if the ama is 8, what is the efficiency of the steering wheel?

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?

Acid precipitation chemically weathering a 5.0-kg limestone rock . which coukd be the result ?