## Conceptual Physics (12th Edition)

This is a writing exercise for the student, and answers will vary. Sample 1: If a clown moves from the top of a 10-m platform to the top of a 20-m platform, by what factor will his weight change? a. Increase by factor of 2 b. Decrease by factor of 2 c. Increase by factor of 4 d. Decrease by factor of 4 e. None of these The correct answer is (e), none of these. Newton's law of gravity refers to the distance between the centers of the two masses, which does not double here. If the clown had climbed to a distance of one Earth radius above the surface, thereby doubling her distance from the Earth's center, THEN her weight would decrease by a factor of 4. Sample 2: If Einstein is standing inside a box in deep space, far from any other masses, and the box begins to accelerate "upward" (as perceived by Einstein) at $10 \frac{m}{s^{2}}$, will he feel weightless? a. Yes b. No The correct answer is (b), no. As discussed on page 166, the broader definition of the weight experienced by something is the force it exerts against a supporting surface. The normal force exerted on Einstein's feet is his mass multiplied by the acceleration. If he stands on a scale, it will have a nonzero reading.