Q. A 95kg diver steps off a 3m tower and drops, from rest, straight down into the water. If he comes to rest 2.5m beneath the surface, find out the average resistance force exerted on him by the water.
Q. Perpetual motion machines have fascinated people especially inventors for hundreds of years before the laws of thermodynamics became known. Ideally, once energy is added to start a perpetual motion in machine, the machine would continue to operate indefinitely. Using a law of thermodynamics, describe why such a machine cannot be produced.