A mechanical rescue hoist is used to lift a medical equipment crate of mass 500 kg500\text{ kg}500 kg from a rescue vessel. An operator pulls down on the hoist's lever with a constant force of 200 N200\text{ N}200 N, moving the lever handle through a distance of 70.0 cm70.0\text{ cm}70.0 cm. As the handle is pulled through this distance, the crate is raised vertically by 2.0 cm2.0\text{ cm}2.0 cm.
Calculate the work done by the 200 N200\text{ N}200 N force.
Calculate the ratio:
speed of the lever handle moving downspeed of the crate moving up \frac{\text{speed of the lever handle moving down}}{\text{speed of the crate moving up}} speed of the crate moving upspeed of the lever handle moving downCalculate the useful work done on the crate and hence the percentage efficiency of the rescue hoist. (Use g=9.81 m s−2g = 9.81\text{ m s}^{-2}g=9.81 m s−2)
13 exam-style questions on OCR A A Level Physics Work, energy and power, covering Work and conservation of energy, Kinetic and potential energies, and Power. Each one has a worked solution and a mark scheme showing where the marks go.