You have always wondered how much one of your friends weighs and devise a scheme to measure his weight secretly. You have him sit in a tubular steel chair. This popular style of chair consists of a single steel tube that is bent into a frame and that supports a seat bottom and a back. The empty chair weighs 10 pounds and is 30 inches tall. The frame acts as a spring and bends downward slightly when the chair is occupied. When you sit properly in the chair yourself, it bends downward 1 inch. When your friend sits properly in the chair, it bends downward 2 inches. From that observation, you know that your friend weighs about
A) 300 pounds.
B) twice as much as you do.
C) four times as much as you do.
D) 150 pounds.

Question

Quizplus · Accepted Answer

The chair bending twice as much under your friend's weight compared to yours indicates that the force (weight) he exerts on the chair is twice as much as the force you exert, assuming a linear relationship between force exerted and displacement (bending) of the chair.

You Have Always Wondered How Much One of Your Friends