Assertion (A): | Water at the foot of the waterfall is always at a different temperature from that at the top. |
Reason (R): | The potential energy of water at the top is converted into heat energy during falling. |
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): | According to the law of conservation of mechanical energy change in potential energy is equal and opposite to the change in kinetic energy. |
Reason (R): | Mechanical energy is not a conserved quantity. |
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): | When a stationary bomb explodes into two pieces, their speeds are in the inverse ratio of their masses. |
Reason (R): | The explosion does not violate the law of conservation of linear momentum. |
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): | Work done by friction on a body sliding down an inclined plane is negative. |
Reason (R): | Work done is less than zero if the angle between force and displacement is acute or both are in the same direction. |
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 work done on bringing a body down from the top to the base along a frictionless inclined plane is the same as the work done in bringing it down the vertical side. |
Reason (R): | The gravitational force on the body along the inclined plane is the same as that along the vertical side. |
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): | No work is done when an electron completes a circular orbit around the nucleus of an atom. |
Reason (R): | Work done by a centripetal force is always 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): | Centripetal force does no work. |
Reason (R): | Force and displacement are perpendicular to each other. |
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): | Work done in uniform circular motion is zero. |
Reason (R): | Force is always directed along displacement. |
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): | In an elastic collision of two billiard balls, the total kinetic energy is conserved during the short time of collision of the balls (i.e. when they are in contact). |
Reason (R): | Energy spent against friction does not follow the law of conservation of energy. |
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): | In an elastic collision between two bodies, the energy of each body is conserved. |
Reason (R): | The total energy of an isolated system 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. | (A) is false but (R) is true. |