## Gravitation Questions and Answers Part-1

1. The tidal waves in the sea are primarily due to
a) The gravitational effect of the moon on the earth
b) The gravitational effect of the sun on the earth
c) The gravitational effect of venus on the earth
d) The atmospheric effect of the earth itself

Explanation: The gravitational effect of the moon on the earth

2. If there were a smaller gravitational effect, which of the following forces do you think would alter in some respect
a) Viscous forces
b) Archimedes uplift
c) Electrostatic force
d) None of the above

Explanation: As it depends on the weight of the body

3. A satellite of the earth is revolving in a circular orbit with a uniform speed v. If the gravitational force suddenly disappears, the satellite will
a) Continue to move with velocity v along the original orbit
b) Move with a velocity v, tangentially to the original orbit
c) Fall down with increasing velocity
d) Ultimately come to rest somewhere on the original orbit

Explanation: Due to inertia of direction

4. The atmosphere is held to the earth by
a) Winds
b) Gravity
c) Clouds
d) None of the above

Explanation: Gravity

5. The weight of a body at the centre of the earth is
a) Zero
b) Infinite
c) Same as on the surface of earth
d) None of the above

Explanation: Zero

6. If the distance between two masses is doubled,the gravitational attraction between them
a) Is doubled
b) Becomes four times
c) Is reduced to half
d) Is reduced to a quarter

Explanation:

7.Which of the following is the evidence to show that there must be a force acting on earth and directed towards the sun
a) Deviation of the falling bodies towards east
b) Revolution of the earth round the sun
c) Phenomenon of day and night
d) Apparent motion of sun round the earth

Explanation: Revolution of the earth round the sun

8. The gravitational force between two stones of mass 1 kg each separated by a distance of 1 metre in vacuum is
a) Zero
b) $6.675\times10^{-5}newton$
c) $6.675\times10^{-11}newton$
d) $6.675\times10^{-8}newton$

Explanation:

9. The earth $\left(mass= 6\times10^{24}kg\right)$     revolves round the sun with angular velocity $2\times10^{-7}rad / s$   in a circular orbit of radius $1.5 \times10^{8}km$  . The force exerted by the sun on the earth in newtons, is
a) $18 \times10^{25}$
b) Zero
c) $27 \times10^{39}$
d) $36 \times10^{21}$