Answer :
Final answer:
In an elevator moving upwards at a constant speed, the scale will show your normal weight. So if your weight is 120 lb, the scale will read 120 lb. The correct answer is A).
Explanation:
The elevator's free-body diagram has three forces, the force of gravity, a downward normal force from you, and an upward force from the tension in the cable holding the elevator. The combined system of you + elevator has two forces, a combined force of gravity and the tension in the cable.
If you are standing on a scale in an elevator that is moving upward with a constant speed of 4 m/s, the reading on the scale would be your normal weight. Since there is no acceleration (as the speed is constant), there's no additional force exerted on you besides the usual force of gravity. Therefore, in this situation, the reading on the bathroom scale would be equal to your weight when you are not in the elevator, which is 120 lb.
