試題詳解

4. If the energy needed to send an object (initially at rest on the earth's surface) to a maximum height H is a half of that for sending it into an orbit at the same height, what would be the value of H in terms of RE (the radius of the earth)? Ignore the earth's rotation.
(A) 1/4；
(B) 1/3；
(C) 1/2；
(D) 2/3；
(E) None.