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Check yourself Answers

1Since F∝1 r 2, the force will become nine times smaller.

2The acceleration is the same as the gravitational field strength.

Hence a=G M r 2=G M(2 R)2=1 4 G M R 2=g 4.

3The force is m g = 0.40 × 15 = 6.0 N.

4When they come near the sun they move very fast and so on the average spend most of their time away from the sun and out of sight.

5 E P = mV = −2.0 × 1010 × 350 = −7.0 × 1012 J

6The force does not stay constant as we move from A to B.

7It is zero since the gradient at P is zero.