Question

Harry is conducting his famous elevator experiments. Harry stands on a bathroom scale and reads the scale while ascending and descending John's building. Harry's mass is 80 kg. He notices that the scale readings depend on what the elevator is doing. What is the scale reading when Harry accelerates upward at 4.0 $m/s^2$?(take g=10$m/s^2$)

• A. 1120 N
• B. 800 N
• C. 566 N
• D. 768 N

Answer 1

The correct option is A

1120 N

Using Newton's second law

$F_N$ - mg = ma

$F_N$ = ma + mg

This $F_N$ is the force exerted by the floor of the elevator and in turn will be the apparent weight of Harry

$F_N$ = 80$\times$10 + 80$\times$4.0

$F_N$ =1120 N