An electric hoist is used at a construction site to lift a concrete block.
The hoist lifts a block of weight 800 N800\text{ N}800 N through a vertical distance of 4.5 m4.5\text{ m}4.5 m in 6.0 s6.0\text{ s}6.0 s.
Calculate the useful work done in lifting the block.
An electric motor drives the hoist mechanism. The current in the motor is 12 A12\text{ A}12 A when it is connected to a 100 V100\text{ V}100 V power supply.
Calculate: (i) the electrical energy supplied to the motor in 6.0 s6.0\text{ s}6.0 s, (ii) the overall efficiency of the hoist in lifting the block.
Suggest two mechanisms by which energy is wasted during this operation.
533 exam-style questions on CIE IGCSE Physics 1.7 Energy, work and power, covering 1.7.1a Energy stores and energy transfers, 1.7.1b Conservation of energy, 1.7.1c Kinetic and gravitational potential energy, 1.7.2 Work done, 1.7.3 Energy resources, 1.7.3a Energy resources and electricity generation, 1.7.3b Nuclear fusion as an energy source, 1.7.3c Efficiency of energy transfer, and 1.7.4 Power. Each one has a worked solution and a mark scheme showing where the marks go.