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

1.   4.2 years                          

2.   2.8 years

3.   5.6 years                          

4.   8.4 years

The diagram showing the variation of gravitational potential of earth with distance r from the centre of earth is -

 

1.		2.
3.		4.

The condition for a uniform spherical mass m of radius r to be a black hole is [G= gravitational constant and g= acceleration due to gravity] .

1. ${\left(2Gm/r\right)}^{1/2}\le c$                

2. ${\left(2Gm/r\right)}^{1/2}=c$ 

3. ${\left(2Gm/r\right)}^{1/2}\ge c$                

4.  ${\left(gm/r\right)}^{1/2}\ge c$

A sphere of mass M and radius R₂ has a concentric cavity of radius R₁ as shown in figure. The force F exerted by the sphere on a particle of mass m located at a distance r from the centre of sphere varies as $(0\le \mathrm{r}\le \infty )$. 

 

1.		2.
3.		4.

Which one of the following graphs represents correctly the variation of the gravitational field (I) with the distance (r) from the centre of a spherical shell of mass M and radius a ?

1.		2.
3.		4.

Suppose, the acceleration due to gravity at the earth’s surface is 10 $\mathrm{m}/{\mathrm{s}}^2$ and at the surface of Mars, it is 4.0 $\mathrm{m}/{\mathrm{s}}^2$. A 60 kg passenger goes from the earth to Mars in a spaceship moving with a constant velocity. Neglect all other objects in the sky. Which part of the figure best represents the weight (net gravitational force) of the passenger as a function of time ?

1. A                             
2. B
3. C                             
4. D

Which of the following graphs represents the motion of a planet moving about the sun ?

1.		2.
3.		4.

The correct graph representing the variation of total energy (${\mathrm{E}}_{\mathrm{t}}$), kinetic energy (${\mathrm{E}}_{\mathrm{k}}$) and potential energy (U) of a satellite with its distance from the centre of the earth is -

1.		2.
3.		4.

What is the intensity of gravitational field of the centre of a spherical shell?

1.     $Gm/r^2$           

2.    g

3.      Zero             

4.    None of these