#### 11th Standard Physics Gravitation English Medium Free Online Test One Mark Questions 2020 - 2021

11th Standard

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Physics

Time : 00:20:00 Hrs
Total Marks : 20

20 x 1 = 20
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. 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)

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

3. 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

4. The work done by the Sun’s gravitational force on the Earth is

(a)

always zero

(b)

always positive

(c)

can be positive or negative

(d)

always negative

5. An object of mass 10 kg is hanging on a spring scale which is attached to the roof of a lift. If the lift is in free fall, the reading in the spring scale is

(a)

98 N

(b)

zero

(c)

49 N

(d)

9.8 N

6. The kinetic energy of the satellite orbiting around the Earth is

(a)

equal to potential energy

(b)

less than potential energy

(c)

greater than kinetic energy

(d)

zero

7. The work done by Sun on Earth in one year will be

(a)

zero

(b)

non-zero

(c)

positive

(d)

negative

8. 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

9. 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)

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

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)

$\frac { r }{ 20 }$

11. A body of mass m falls from earth's surface at a height equal to twice the radius (R) each. Then the change in P.E of body will be

(a)

2 mgR

(b)

$\frac { 2 }{ 3 }$ mgR

(c)

3 mgR

(d)

$\frac { 1 }{ 3 }$ mgR

12. Starting from the centre of be each having radius R, the variation of g is shown by

(a)

(b)

(c)

(d)

13. Let V & E be gravitational potential & gravitational field at a distance r from the centre of a uniform solid sphere, consider the 2 statements
(A) the plot of V against r is discontinuous
(B) the plot of E against r is discontinuous

(a)

both A & B correct

(b)

A is correct but B is wrong

(c)

B is correct but A is wrong

(d)

both A & B wrong

14. A body is suspended from a spring balance kept in a satellite the reading of the balance is W1 when the satellite goes in an orbit of radius R and isW2 when it goes in an orbit of radius 2R

(a)

W1=W2

(b)

W1<W2

(c)

W1>W2

(d)

W1W2

15. A satellite is orbiting the earth close to its surface. A particle is to be projected from the satellite to just escape from the earth the escape speed from the earth is Ve its speed with respect to the satellite

(a)

will be less than Ve

(b)

will be more than Ve

(c)

will be equal to Ve

(d)

will depend on direction of projection

16. Bernoulli theorem is based on conservation of

(a)

momentum

(b)

mass

(c)

energy

(d)

angular momentum

17. A solid floats in a liquid in a partially dipped position

(a)

The solid exerts a force equal to its weight on the liquid

(b)

The liquid exerts a force of buoyancy on the solid which is equal to the weight of the solid

(c)

The weight of the displaced liquid equals the weight of the solid

(d)

All the above

18. In a streamline flow

(a)

the speed ofa particle always remain same

(b)

the velocity of a particle always remains same

(c)

the kinetic energies of all the particles arriving at a given point at the same

(d)

the moments of the particles arriving at a given point are different

19. When a metal wire is stretched by a .load, the fractional change in its volume ΔV/V is proportional to

(a)

$\frac { \triangle l }{ l }$

(b)

$\left( \frac { \triangle l }{ l } \right) ^{ 2 }$

(c)

$\sqrt { \frac { \triangle l }{ l } }$

(d)

none of these

20. If two soap bubbles of different radii are connected by a tube, then

(a)

air flows from bigger to the smaller bubble till the sizes become equal

(b)

air flows from bigger bubble to the smaller bubble till the size are interchanged

(c)

air flows from the smaller bubble to the bigger

(d)

there is number flow of air