A block and tackle pulley system is used on a construction site to lift a heavy steel beam of mass 180 kg. A worker pulls the rope of the pulley system with a constant force of 240 N, pulling a length of 12.0 m of rope. As a result, the steel beam is lifted vertically through a distance of 1.2 m.
Calculate the work done by the 240 N force.
Calculate the ratio:
speed of the rope being pulledspeed of the steel beam rising \frac{\text{speed of the rope being pulled}}{\text{speed of the steel beam rising}} speed of the steel beam risingspeed of the rope being pulledCalculate the useful work done on the steel beam and hence the percentage efficiency of the pulley system. (Use g=9.8 m s−2g = 9.8\text{ m s}^{-2}g=9.8 m s−2 or g=9.81 m s−2g = 9.81\text{ m s}^{-2}g=9.81 m s−2)
