An escalator between two floors in a shop consists of steps that are each 30 cm high and 40 cm deep.
There are 20 steps between the floors.
The escalator moves a person of mass 80 kg upwards from the lower floor to the upper floor.
How much work is done by the escalator on the person?
(gravitational field strength = 10 N kg–1)

Answer:

15) D

Weight of person = mass x gravitational field strength = 80 x 10 = 800 N
Height of each step = 30 cm = 0.3 m
Height of escalator = number of steps x height of each step = 20 x 0.3 m = 6 m
GPE of person at 6m = 800 x 6 = 4800 J