Question

question 2
suppose you are riding an elevator with your bathroom scales. while standing on your scale, the elevator begins a trip to the upper floors. as the elevator starts to move up, what happens to the reading on your scale?
a scale reading remains unchanged
b scale reading decreased
c scale reading increases

Explanation:

Step1: Analyze forces on person in elevator

When the elevator is at rest, the normal force $N$ on the person from the scale equals the person's weight $mg$, i.e., $N = mg$. When the elevator starts moving up, it has an upward acceleration $a$. According to Newton's second - law $F_{net}=ma$. The net force acting on the person is $F_{net}=N - mg$ (taking upward as positive). So $N - mg=ma$, and $N = m(g + a)$.

Step2: Relate normal force to scale reading

The scale reading is equal to the normal force exerted on the person by the scale. Since $N = m(g + a)$ and initially $N = mg$, the new normal force $N$ is greater than the initial normal force when the elevator starts moving up. So the scale reading increases.

Answer:

C. Scale reading increases