#### 11th Standard Physics Motion of System of Particles and Rigid Bodies English Medium Free Online Test One Mark Questions with Answer Key 2020 - 2021

11th Standard

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Physics

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

20 x 1 = 20
1. The center of mass of a system of particles does not depend upon,

(a)

position of particles

(b)

relative distance between particles

(c)

masses of particles

(d)

force acting on particle

2. The angular momentum of a system of particles is conserved

(a)

When no external force acts upon the system

(b)

When no external torque acts upon the system

(c)

When no external impulse acts upon the system

(d)

When axis of rotation remains same

3. If earth suddenly contracts to 0.75 times of its present radius, then the length of the day becomes

(a)

12 hr

(b)

18 hr

(c)

15.5 hr

(d)

13.5 hr

4. A particle is moving with a constant velocity along a line parallel to positive X-axis. The magnitude of its angular momentum with respect to the origin is,

(a)

zero

(b)

increasing with x

(c)

decreasing with x

(d)

remaining constant

5. From a disc of radius R a mass M, a circular hole of diameter R, whose rim passes through the center is cut. What is the moment of inertia of the remaining part of the disc about a perpendicular axis passing through it

(a)

15MR2/32

(b)

13MR2/32

(c)

llMR2/32

(d)

9MR2/32

6. The speed of a solid sphere after rolling down from rest without sliding on an inclined plane of vertical height his,

(a)

$\sqrt \frac{4}{3}gh$

(b)

$\sqrt \frac{10}{7}gh$

(c)

$\sqrt{2gh}$

(d)

$\sqrt \frac{1}{2}gh$

7. A round object of mass M and radius R rolls down without slipping along an inclined plane. The fractional force

(a)

dissipates kinetic energy as heat.

(b)

decreases the rotational motion.

(c)

decreases the rotational and transnational motion

(d)

converts transnational energy into rotational energy

8. Where will be the centre of mass on combining two masses m and M (M > m)?

(a)

Towards m

(b)

Towards M

(c)

Between m & M

(d)

away from m & M

9. Two objects which are initially at rest, move towards each other under the action of their internal attraction. If their speeds are 4 v and 2 v at any instant, then the speed of centre of mass of the system will be

(a)

2v

(b)

zero

(c)

V

(d)

1.5 v

10. If I, $\alpha$ . and $\tau$ are MI, angular acceleration and torque respectively of a body rotating about any axis with angular velocity $\omega$ , then

(a)

$\tau =I\omega$

(b)

$\tau =I\alpha$

(c)

$\alpha =r\omega$

(d)

$\alpha =r\omega$

11. Consider a system of two identical particles. One is at rest and the other has an acceleration $\overrightarrow { a }$ .The centre of mass has an acceleration

(a)

1/2$\overrightarrow { a }$

(b)

$\overrightarrow { a }$

(c)

2$\overrightarrow { a }$

(d)

Zero

12. Three identical spherical shells, each of mass m and radius r are placed as shown in.figure. Consider an axis xx1 which is touching to two shells and passing through diameter of third shell. M.I of the system consisting of these three spherial shells about xx1 axis is

(a)

3mr2

(b)

4mr2

(c)

16/5mr2

(d)

11/5 mr2

13. The direction of angular velocity vector is along

(a)

The tangent to the circular path

(b)

(c)

(d)

The axis of rotation

14. The M.I of a uniform circular disc is maximum about an axis perpendicular to the disc and passing through

(a)

B

(b)

D

(c)

A

(d)

C

15. A sphere of radius r is rolling without sliding. What is ratio of rotational K.E and total K.E associated with the sphere?

(a)

2/5

(b)

2/7

(c)

1

(d)

1/2

16. A sphere rolls down an inclined plane of inclination $\theta$ . What is the acceleration as the sphere reaches bottom?

(a)

5/7 sin$\theta$

(b)

3/5 sin $\theta$

(c)

2/6 g sin $\theta$

(d)

2/5 g sin $\theta$

17. Two rings of radii R & nR made from the same wire have the ratio of M.I about an axis passing through their centre equal to 1 : 8. The value of n is

(a)

2

(b)

2$\sqrt{2}$

(c)

4

(d)

1/2

18. If a solid sphere and solid cylinder of same mass and radius rotate about their own axis the M.I. will be greater for

(a)

Solid sphere

(b)

Solid cylinder

(c)

Both (a) and (b)

(d)

Equal both

19. Analogue of mass in rotational motion is

(a)

M.l.

(b)

Angular momentum

(c)

Gyration

(d)

Torque

20. M.I. of an object does not depend upon

(a)

Mass of object

(b)

Angular velocity

(c)

Mass distribution .

(d)

Axis of rotation