Q. A rocket is modelled by a particle which moves along a vertical line. From launch, the rocket rises until its motor cuts out after 20 seconds. At this time it has reached a height of 420 metres above the launch pad and attained an upward velocity of 50 ms-1. From this time on, the rocket has constant upward acceleration -10 ms-2 (due to the effect of gravity alone).
Q. A man pushes a lawn mower on a level lawn with a force of 207 N. If 30 percent of this force is directed downward, how much work is done by the man in pushing the mower 7.5 m?