If a body of mass \(m\) placed on the earth's surface is taken to a height of \(h = 3R,\) then the change in gravitational potential energy is:
1. \(\dfrac{mgR}{4}\)
2. \(\dfrac{2}{3} mgR\)
3. \(\dfrac{3}{4} mgR\)
4. \(\dfrac{mgR}{2}\)
| 1. | \(\dfrac{g}{R}\) | 2. | \(\dfrac{R}{g}\) |
| 3. | \(gR\) | 4. | \(\dfrac{g}{R^{2}}\) |
A body of mass \(m\) is taken from the earth's surface to the height \(h\) equal to the radius of the earth, the increase in potential energy will be:
1. \(mgR\)
2. \(\dfrac{1}{2}mgR\)
3. \(2 ~mgR\)
4. \(\dfrac{1}{4}~mgR\)
| 1. | \(\dfrac{GMm}{r}\) | 2. | \(\dfrac{-GMm}{r}\) |
| 3. | \(\dfrac{GM}{r}\) | 4. | \(\dfrac{-GM}{r}\) |
| \(\mathrm{(A)}\) | The kinetic energy of the earth | \(\mathrm{(I)}\) | \(-\dfrac{G M_s M_e}{a}\) |
| \(\mathrm{(B)}\) | The potential energy of the earth and the sun | \(\mathrm{(II)}\) | \(\dfrac{G M_s M_e}{2 a}\) |
| \(\mathrm{(C)}\) | The total energy of the earth and the sun | \(\mathrm{(III)}\) | \(\dfrac{G M_e}{R}\) |
| \(\mathrm{(D)}\) | Escape energy from the surface of the earth per unit mass | \(\mathrm{(IV)}\) | \(-\dfrac{G M_s M_e}{2 a}\) |
| 1. | \(\mathrm{A\text-II,B\text-I,C\text- IV,D\text- III}\) |
| 2. | \(\mathrm{A\text-I,B\text-II,C\text- III,D\text- IV}\) |
| 3. | \(\mathrm{A\text-III,B\text-IV,C\text- I,D\text- II}\) |
| 4. | \(\mathrm{A\text-IV,B\text-III,C\text- II,D\text- I}\) |