Question

When you weigh yourself on solid ground, your weight is 133 lb. In an elevator, your apparent weight is 113 lb. What is the difference in your weight between solid ground and the elevator?

1) 20 lb
2) 30 lb
3) 40 lb
4) 50 lb

Answer 1

The difference in weight between solid ground and an elevator is 20 lb, reflecting a decrease in apparent weight due to the downward acceleration of the elevator. The actual weight remains unchanged; variations in scale readings are due to changes in the normal force in response to elevator acceleration.

Step-by-step explanation:

When you weigh yourself on solid ground, your weight is observed to be 133 lb. However, when your apparent weight in an elevator is 113 lb, we can determine the difference in your weight between on solid ground and in the elevator by simple subtraction: 133 lb - 113 lb = 20 lb. The difference in your weight is therefore 20 lb, which means that the elevator must be accelerating downwards for you to feel lighter. In physics, your actual weight is the force due to gravity on your mass, and it does not change. In an elevator, the scale reading reflects the normal force exerted on you by the scale, which can vary depending on the acceleration of the elevator. If the elevator is accelerating downward, you feel lighter, and if it's accelerating upward, you feel heavier. If an elevator cable were to snap and the elevator were in free fall, you would feel weightless, and the scale would read 0, since there would be no normal force exerted on you by the scale.