A geostationary satellite orbits around the earth in a circular orbit of radius $36000~\text{km}$. Then, the time period of a satellite orbiting a few hundred kilometres above the earth’s surface $(R_{earth}= 6400~\text{km})$ will approximately be:
1. $\frac{1}{2}~\text{hrs}$
2. $1~\text{hrs}$
3. $2~\text{hrs}$
4. $4~\text{hrs}$

A planet revolves around the sun whose mean distance is 1.588 times the mean distance between earth and the sun. The revolution time of the planet will be:

1. 1.25 years                               

2. 1.59 years

3. 0.89 years                               

4. 2 years

The earth E moves in an elliptical orbit with the sun S at one of the foci as shown in figure. Its speed of motion will be maximum at the point

1. C

2. A

3. B

4. D

The period of revolution of planet A around the sun is 8 times that of B. The distance of A from the sun is how many times greater than that of B from the sun ?

1. 2                                         

2. 3                                      

3. 4                                        

4. 5

If the radius of earth's orbit is made 1/4 th, the duration of an year will become -

1. 8 times                                     

2. 4 times

3. 1/8 times                                   

4. 1/4 times

If the mass of a satellite is doubled and the time period remain constant, the ratio of orbit in the two cases will be

1.  1 : 2                                   

2.   1 : 1

3.   1 : 3                                   

4.   None of these

The maximum and minimum distances of a comet from the sun are $8\times {10}^{12}$ m and $1.6\times {10}^{12}$ m. If its velocity when nearest to the sun is 60 m/s, what will be its velocity in m/s when it is farthest -

1. 12                                      

2. 60

3. 112                                     

4. 6

A body revolved around the sun 27 times faster than the earth. What is the ratio of their radii?

1.   1/3                                    

2.   1/9

3.   1/27                                  

4.   1/4

The period of the moon’s rotation around the earth is nearly 29 days. If the moon’s mass were 2 fold, its present value and all other things remained unchanged, the period of the moon’s rotation would be nearly:

1.$\mathrm{ 29}\sqrt{2} days$                                       

2.$\mathrm{ 29}/\sqrt{2} days$

3. $29\times 2 days$                                       

4. 29 days

If two planets are at mean distances $d_1$ and $d_2$ from the sun and their frequencies are $n_1$ and $n_2$ respectively, then:
1. $n^2_1d^2_1= n_2d^2_2$
2. $n^2_2d^3_2= n^2_1d^3_1$
3. $n_1d^2_1= n_2d^2_2$
4. $n^2_1d_1= n^2_2d_2$