In an earth's satellite, the astronaut stands on a platform. His weight as indicated by the balance will be

• 6g

• 2g

• 8g

• zero

A body of mass m is moved to a height h equal to the radius of the earth. The increase in potential energy is

• 2mgR

• mgR

• $\frac{1}{2}\mathrm{mgR}$

• $\frac{1}{4}\mathrm{mgR}$

Escape velocity from a planet is v, If its mass is increased to 8 times and its radius is increased to 2 times, then the new escape velocity would be :

• v_e

• $\sqrt{2}$v_e

• 2v_e

• $2\sqrt{2}$v_e

Acceleration due to gravity:

• decreases from the equator to poles

• decreases from poles to the equator

• is maximum at the centre of the earth

• is maximum at the equator

The distance between the sun and the earth be r then the angular momentum of the earth around the sun is proportional to :

• $\sqrt{\mathrm{r}}$

• ${\mathrm{r}}^{3/2}$

• r

• none of these

The length of the second's pendulum is 1 m on earth. If the mass and diameter of a planet are doubled than that of earth. Then its length becomes

• 1 m

• 2 m

• 0.5 m

• 4 m

Two satellites A and B go around a planet P in circular orbits having radius 4 R and R respectively. If the speed of satellite A is 3v, then the speed of satellite B will be

• 6v

• 9v

• 3v

• none of these

The period of oscillation of a simple pendulum of constant length at the surface of the earth is T. Its time period inside a mine will be :

• can not be compared

• equal to T

• less than T

• more than T

The radius of orbit of satellite of earth is R. Its kinetic energy is proportional to :

• $\frac{1}{\mathrm{R}}$

• $\frac{1}{\sqrt{\mathrm{R}}}$

• R

• $\frac{1}{{\mathrm{R}}^{3/2}}$

The radius of orbit of a planet is two times that of the earth. The time period of the planet is :

• 4.2 T

• 2.8 T

• 5.6 T

• 8.4 T