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. | \(a_{cm}=\dfrac{F_1-F_2}{m+M},\) if there is no friction acting between \(m\) and \(M\) |
B. | \(a_{cm}=\dfrac{F_1-F_2}{m+M},\) if there is static friction between \(m\) and \(M\) |
C. | \(a_{cm}=\dfrac{F_1-F_2}{m+M},\) in all situations |
1. | only (A) is true. |
2. | only (B) is true. |
3. | (C) is true. |
4. | (A), (B) are true but (C) is false. |
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): | A ladder is more apt to slip when you are high up on it than when you just begin to climb. |
Reason (R): | At high up on a ladder, the torque is large and on climbing up, the torque is small. |
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 there is no external torque on a body about its centre of mass, then the velocity of the centre of mass remains constant. |
Reason (R): | The linear momentum of an isolated system remains constant. |
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): | The speed of a whirlwind in a tornado is alarmingly high. |
Reason (R): | If no external torque acts on a body, its angular velocity remains 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): | 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): | The centre of mass of an electron and proton when released moves faster towards the proton. |
Reason (R): | This is because the proton is heavier. |
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. |