More practice questions

4. Q4. Compare g at a height of R_E/2 above the surface with g at a depth of R_E/2 below it.

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   Height: g/(1.5)^² = 4g/9, about 0.444g. Depth: g(1 − ½) = 0.5g. So g is larger at the depth (0.5g against about 0.44g).

5. Q5. A body weighs 72 N on the Earth’s surface. What does it weigh at a height of R_E/2?

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   W = 72/(1 + ½)^² = 72/2.25 = 32 N.

6. Q6. What would a 50 kg body weigh at the centre of the Earth, treated as uniform? What would its mass be?

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   Its weight would be zero, because g = 0 at the centre; its mass would still be 50 kg.