#### Gravitation Three Marks Questions

11th Standard

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Physics

Time : 00:45:00 Hrs
Total Marks : 30
10 x 3 = 30
1. A student was asked a question ‘why are there summer and winter for us? He replied as ‘since Earth is orbiting in an elliptical orbit, when the Earth is very far away from the Sun(aphelion) there will be winter, when the Earth is nearer to the Sun(perihelion) there will be winter’. Is this answer correct? If not, what is the correct explanation for the occurrence of summer and winter?

2. The following photographs are taken from the recent lunar eclipse which occurred on January 31, 2018. Is it possible to prove that Earth is a sphere from these photographs?

3. Why the gravitational force between the Earth and the Sun is so great while the same force between two small objects is negligible?

4. Obtain an expression for Gravitational Field intensity measured with an object of unit mass.

5. What will be the potential energy of a body of mass 67kg at a distance of 6.6x 1010mfrom the centre of the earth? Find gravitational potential at this distance

6. A mass M is broken into two parts, on & (M-m). How is m related to M so that the gravitational force between two parts is maximum?

7. Draw graphs showing the variation of acceleration due to gravity with (i) height above the earth's surface (ii) depth below the earth's surface.

8. Suppose the gravitational force varies inversely as the nth power of distance then, fine the expression for the time period of a planet in a circular orbit of radius r around the sun.

9. A simple pendulum has a .times period T1 when on the earth's surface & T2 when taken to a hight & above the earth's surface, where R is the radius of the earth. What is the value of T2/T1?

10. Find the period of oscillation of a simple pendulum of length $\alpha$ suspended from the roof a vehicle which moves without friction down an inclined plane of inclination $\alpha.$