A slimming club is situated at the top of a building; to motivate its clientele, the club has installed its own lift which contains a weighing machine. The lift accelerates uniformly at 1.0ms-2 for 90% of its journey, both going up and coming down.
(iv) The reading (in kg) on the weighing machine when the 80kg person stands on it as the lift decelerates upwards at 2.0ms-2?
Not sure if I'm doing this right... F=mg+ma
So F=80x9.81+80x-2
F=784.8+-160
624.8 / 9.81 = 63.69 = 64KG???
Or
F=80x9.81+80x2
F=784.8+160
944.8 / 9.81 = 96.3 = 96KG???
Or am I doing this completely wrong??? Well, at least I tried! Thanks!