Question

A man rides in an elevator while standing on a bathroom scale calibrated to read force in Newtons. As the elevator starts to move upwards it speeds up with an acceleration of magnitude 2.1 m/s2. The scale displays a force of 844.9 N . What is the man’s mass?

Answer 1

Answer:

71 Kg

Explanation:

a = 2.1 m/s²

R = 844.9 N  

We can apply Newton's Second Law as follows:

R – W = m*a

R – m*g = m*a  

m*a + m*g = R

m (a + g) = R

m = R / (a + g)

m = (844.9 N) / (2.1 m/s² + 9.81 m/s²) = 71 Kg