Assertion (A): A particle on earth found to be at rest when seen from a frame \(U_1\) and moving with a constant velocity when seen from another frame \(U_2\). Then both frames may be non-inertial.
Reason (R): A reference frame attached to the earth must be an inertial frame.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. Earth is a non-inertial frame, so frames observing a particle on Earth can also be non-inertial. Reason (R) is false because a frame attached to Earth is technically non-inertial due to Earth's rotation and orbital motion.
Assertion (A): If pseudo force on a body is assumed as action then frictional force may be reaction for this action.
Reason (R): Action-reaction must acts on different bodies.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is false. Pseudo forces are fictitious and do not constitute action-reaction pairs with real forces like friction, as they are not interaction forces.
Reason (R) is true. According to Newton's third law, action and reaction forces always act on different bodies. Since (A) is false and (R) is true, and no option directly reflects this, the closest option, given (A) is false, is (4), implying both are false, despite (R) being true. This indicates a potential flaw in the provided options.
Assertion (A): A man standing in a lift which is moving upward, will feel his weight to be greater than when the lift was at rest.
Reason (R): If the acceleration of the lift is ‘a’ upward, then the man of mass m shall feel his weight to be equal to normal reaction (N) exerted by the lift given by \(N = m(g – a)\) (where \(g\) is acceleration due to gravity)
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
When a lift accelerates upwards, apparent weight is \(N = m(g + a)\), which is greater than \(mg\). So (A) is true. Reason (R) provides the formula for downward acceleration, thus (R) is false.