A physics student sets up a floor scale in an elevator in his apartment complex. A 95 kg?

Question : A physics student sets up a floor scale in an elevator in his apartment complex. A 95 kg?
A physics student sets up a floor scale in an elevator in his apartment complex. A 95 kg?
neighbor stands on the scale in the elevator and is pleased to see that she only weighs 850 N as the elevator comes to a stop at the 3rd floor. what is the acceleration(decceleration) of the elevator as it is coming to a stop?
floor scale

Best answer:

Answer by gintable
The scale measures the normal force between the floor and the neighbor.

On a stationary floor, her weight is the weight that corresponds to her mass via value of g.
When in a slowing down elevator, it measures differently.

Forces on her:
N: normal force (upward)
W: weight = m*g (downward)

Newton’s 2nd Law equation (assuming downward acceleration):
Note: downward acceleration is the case when an ascending elevator comes to a stop
W – N = m*a

Solve for a:
a = (W – N)/m

Substitute:
a = (m*g – N)/m

Plug in data:
N := 850 N; m:= 95 kg; g:=9.8 N/kg

Result:
a = 0.8526 m/sec^2