Assertion (A): | If the sun were to 'suddenly' be removed, then the earth would continue to move around in its orbit. |
Reason (R): | Angular momentum of a system of particles is conserved when there is no external torque. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | (A) is False but (R) is True. |
P. | Momentum of the system is conserved. |
Q. | Kinetic energy of the system does not change after the collision. |
R. | Angular momentum of the system is conserved. |
A particle of mass m moves with a constant velocity along 3 different paths, DE, OA and BC. Which of the following statements is not correct about its angular momentum about point O?
1. | It is zero when it is at A and moving along OA. |
2. | The same at all points along the line DE. |
3. | Of the same magnitude but oppositely directed at B and D. |
4. | Increases as it moves along the line BC. |
Assertion (A): | The angular momentum of system always remains constant. |
Reason (R): | \(\tau_{ext} = {dL \over dt} = 0\) | For a system,
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | (A) is False but (R) is True. |
Assertion (A): | If polar ice melts, days will be longer. |
Reason (R): | Moment of inertia increases and thus angular velocity decreases. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Assertion (A): | For a system of particles under a central force field, the total angular momentum is conserved. |
Reason (R): | The torque acting on such a system is zero. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | Both (A) and (R) are False. |
Assertion (A): | If the ice cap of the pole melts, the day length will shorten. |
Reason (R): | Ice flows towards the equator and decreases the moment of inertia of the earth. This increases the frequency of rotation of the earth. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | Both (A) and (R) are False. |
Assertion (A): | A person standing on a rotating platform suddenly stretched his arms. The platform slows down. |
Reason (R): | This happens as angular momentum is conserved. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Assertion (A): | There are very small sporadic changes in the period of rotation of the earth. |
Reason (R): | The shifting of large air masses in the earth's atmosphere produces a change in the moment of inertia of the earth causing its period of rotation to change. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |