Physics

Problem

A crane raises a

250\,\text{kg}

steel beam to a height of

20\,\text{m}

. If the crane’s motor is

80\%

efficient, how much electrical energy must the motor use? (Take

g = 10\,\text{m/s}^{2}

.) a)

5.0\times10^{4}\,\text{J}

6.25\times10^{4}\,\text{J}

1.0\times10^{5}\,\text{J}

4.0\times10^{4}\,\text{J}