Question

A 650 N student stands on a scale in an elevator. As the elevator starts to move, the scale reads 780 N.
a. Find tha acceleration.
b. Is the elevator going up or down?

Answer 1

a. Since Fnet = m a, a = Fnet/m
Now we need values for the net force and the mass.

Fnet = 780 - 650 = 130 kg m/s^2
is the net force acting on the student.

The mass m is weight/g = 650/g
= 66.3 kg

a = 130/66.3 = 1.96 m/s^2

b. The student could be accelerating while going up, or decelerating while going down.