Question

Please help me with the following conceptual problem (click to see).

Answer 1

Consider two identical objects released from rest high above the surface of the earth (neglect air resistance for this question).

Answer 2

In Case 1 we release an object from a height above the surface of the earth equal to 1 earth radius, and we measure its kinetic energy just before it hits the earth to be K1.
In Case 2 we release an object from a height above the surface of the earth equal to 2 earth radii, and we measure its kinetic energy just before it hits the earth to be K2.

Answer 3

Compare the kinetic energy of the two objects just before they hit the surface of the earth.

Answer 4

K2 = 2 K1
K2 = 4 K1
K2 = (4/3) K1
K2 = (3/2) K1

Answer 5

Apply Newtons third equation of uniformly accelerated motion v2-u2=2as for both the situations in first case s=R and in second case s=2R, in both cases u=0 and a=g. so v2 in second case is double than first case hence the kinetic energy will also be double.