# Weight in an elevator? Free body diagrams

A 60kg student is standing on a scale in an elevator that measures weight in newtons. Calculate the reading on the scale if the elevator is accelerating down at 4 m/s^2…..when the elevator is accelerating up at 4 m/s^2…. and in free fall.

Not sure if my work/answer is correct

accelerating down (up is positive)

Fnet= Fn – Fg

ma = Fn – mg

(60)(-4)= Fn – (60)(-9.8)

-240 = Fn +588

Fn = -828

∴ Fn = 828 N(Down)

accelerating up (up is positive)

Fnet = Fn – Fg

240 = Fn +588

Fn = -348

∴Fn = 348 N(down)

Free fall: the weight of the student is the same as if he/she were standing on the ground(588N) since gravity is still present and the student’s mass remains constant.

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