#### Gravitation One Mark Questions

11th Standard

Reg.No. :
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Physics

Time : 00:30:00 Hrs
Total Marks : 10
10 x 1 = 10
1. The linear momentum and position vector of the planet is perpendicular to each other at

(a)

perihelion and aphelion

(b)

at all points

(c)

only at perihelion

(d)

no point

2. If the masses of the Earth and Sun suddenly double, the gravitational force between them will

(a)

remain the same

(b)

increase 2 times

(c)

increase 4 times

(d)

decrease 2 times

3. A planet moving along an elliptical orbit is closest to the Sun at distance r1 and farthest away at a distance of r2. If v1 and v2 are linear speeds at these points respectively. Then the ratio ${v_1\over v_2}$ is

(a)

${r_2\over r_1}$

(b)

$({r_2\over r_1})^2$

(c)

${r_1\over r_2}$

(d)

$({r_1\over r_2})^2$

4. According to Kepler’s second law, the radial vector to a planet from the Sun sweeps out equal areas in equal intervals of time. This law is a consequence of

(a)

conservation of linear momentum

(b)

conservation of angular momentum

(c)

conservation of energy

(d)

conservation of kinetic energy

5. The gravitational potential energy of the Moon with respect to Earth is

(a)

always positive

(b)

always negative

(c)

can be positive or negative

(d)

always zero

6. Acceleration to Kepler's second law the radius vector of a planet sweeps out equal areas in equal intervals of fire. The law is consequence of conservations of

(a)

linear momentum

(b)

angular momentum

(c)

energy

(d)

Newton's law of gravitation

7. A satellite is launched into a circular orbit of radius R around the earth. A second satellite is launched into an orbit of radius 4R. The ratio of their respective periods is

(a)

4:1

(b)

1:8

(c)

8:1

(d)

1:4

8. Two practicals of equal mass m go round a circle of radius R under the action of their mutual gravitational attraction. the speed of each particle is

(a)

$\frac { 1 }{ 2R } \sqrt { \frac { 1 }{ Gm } }$

(b)

$\frac { Gm }{ 2R }$

(c)

$\frac { 1 }{ 2 } \sqrt { \frac { GM }{ R } }$

(d)

$\sqrt { \frac { 4GM }{ R } }$

9. A body projected electrically from the earth reaches a height equal to earth's radius before returning to the earth: The power exerted by the gravitational force is greatest

(a)

at the highest position of the body

(b)

at the instant just before the body hits the earth

(c)

it remains constant all through

(d)

at the instant just after the body is projected

10. A rocket is fired from the earth. The body is projected the distance between the earth of the moon is r & the mass of the earth is 81 times the mass of the moon. The gravitational force on the rocket will be zero, when its from the moon is

(a)

$\frac { r }{ 5 }$

(b)

$\frac { r }{ 10 }$

(c)

$\frac { r }{ 15 }$

(d)

$\frac { r }{ 20 }$