A student argued that there is less gravity on the moon than on earth. The stundent explained: "You need an atmosphere to have gravity, The moon doesnt have an atmosphere and therefore doesnt have a lot of gravity. Earth hasa thick atmosphere and therefore has much more gravity.

A980-kg sports car collides into the rear end of a 2300-kg suv stopped at a red light. the bumpers lock, the brakes are locked, and the two cars skid forward 2.6m before stopping. the police officer, estimating the coefficient of kinetic friction between tires and road to be 0.80, calculates the speed of the sports car at impact. what was that speed?