Assertion (A): A reference frame attached to the earth is an inertial frame of reference.
Reason (R): In practical, Newton’s laws can be applied in a frame of reference. Which is attached to the earth.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is false. The Earth rotates and revolves, making a frame attached to it non-inertial. Reason (R) is false. Newton's laws in their original form are only valid in inertial frames. For a frame attached to the Earth, pseudo forces must be introduced to apply Newton's laws. Thus, both the Assertion and the Reason are false.
Assertion (A): An observer confined to a windowless box cannot tell by any experiment whether he is stationary or in uniform motion with constant velocity w.r.t. the fixed stars.
Reason (R): The basic laws of Physics are identical in all reference systems that move with uniform velocity w.r.t. one another.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true. This is a fundamental statement of the Galilean principle of relativity. Reason (R) is true. The laws of physics are invariant in all inertial frames of reference. (R) correctly explains (A) because if physical laws are identical in all inertial frames, no internal experiment can distinguish between them.
A moongphaliwala sells his moongphali using a weighing machine in an elevator.
Assertion (A): He gains more profit if the elevator is accelerating up.
Reason (R): The apparent weight of an object increases in an elevator while accelerating upward.
1. (1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. (2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (3) (A) is true but (R) is false
4. (4) Both (A) and (R) are false
View Answer
Assertion (A) is true: If the elevator accelerates upwards, the apparent weight \(N = m(g+a)\) of the peanuts increases. If the moongphaliwala sells by the apparent weight reading (e.g., "1 kg" on the scale), they would be selling a *smaller actual mass* \(m_text{actual} = N/(g+a)\) for the same indicated weight. Thus, they gain more profit.
Reason (R) is true: When an elevator accelerates upwards, the normal force (apparent weight) on an object of mass \(m\) is \(N = m(g+a)\), which is greater than its actual weight \(mg\). Reason (R) correctly explains why the apparent weight increases, leading to the profit gain described in (A).