Question

A diver stands a top a platform that is $15$ meters high. After diving, She challenges herself from a cliff that is $30$ meters high. Since she is twice as far from the surface of the earth when she is on the cliff as compared with the diving board. how does her weight on the cliff compare with her weight on the diving board?

• A. Her weight on the cliff is half as much.
• B. Her weight on the cliff is one-fourth as much.
• C. Her weight on the cliff is about the same.
• D. Her weight on the cliff is twice as much.
• E. Her weight on the cliff is four times as much.

Answer 1

The correct option is C Her weight on the cliff is about the same.

Newton's law of universal gravitation helps us answer this question

$F=G\frac{{m_{1}m}_2}{r^2}$

The r in the denominator is the distance between centers of masses of objects -not between their surfaces

This is especially important to take into account when applying the equation to large objects like earth . the difference in distance between the diver and the center of the earth is insignificantly different when she is standing on the cliff compared to when she is standing on the diving board .

hence her weight is only very slightly different - about the same

so the correct choice is option "c"