Energy, Work and Power

# Energy, Work and Power problem 3

Which of the following statements about work is true?

• The work done by a body is greater when more time is expended.

• The force acting in the opposite direction to the movement of a body does not do any work.

• When an electric drill is used to make a hole in a wall, work is done by the electric drill.

• A groom lifts his bride from the ground to a height and then walks a distance ahead. He only does work when he is lifting the bride.

• A force is used to stop the downward movement of a trolley. Work is done on the trolley.

• We applied a push to a cabinet, but it does not move. Our work is zero.

• A car that moves faster does more work than a car that moves slower on the same route, considering air resistance.

• Satellite orbits the Earth above the equator at an altitude of 36,000 km. During orbit, the attractive force (centripetal force) between the Earth and the satellite does the work.

• Current water from a dam falls on a power plant's turbines. In doing so, it does the work.