Question

A child accelerates upwards in an elevator which causes his apparent weight to become 405N. Determine the magnitude of the elevators acceleration if his normal weight is 400N.

Answer 1

m g = 400
m = 400/g

m g + m a = 405
(400/g)(g+a) = 405
400 (g+a) = 405 g
400 a = 5 g
a = g/80 = .123 m/s^2