Assertion (A): | A standing bus suddenly accelerates. If there was no friction between the feet of a passenger and the floor of the bus, the passenger would move back. |
Reason (R): | In the absence of friction, the floor of the bus would slip forward under the feet of the passenger. |
1. | (A) is True but (R) is False. |
2. | (A) is False but (R) is True. |
3. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
4. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
A particle moving with velocity \(\vec{v}\) is acted by three forces shown by the vector triangle \({PQR}.\) The velocity of the particle will:
1. | change according to the smallest force \({\overrightarrow{Q R}}\) |
2. | increase |
3. | decrease |
4. | remain constant |
A rigid ball of mass \(M\) strikes a rigid wall at \(60^{\circ}\) and gets reflected without loss of speed, as shown in the figure. The value of the impulse imparted by the wall on the ball will be:
1. | \(Mv\) | 2. | \(2Mv\) |
3. | \(\dfrac{Mv}{2}\) | 4. | \(\dfrac{Mv}{3}\) |
The force \(F\) acting on a particle of mass \(m\) is indicated by the force-time graph shown below. The change in momentum of the particle over the time interval from \(0\) to \(8\) s is:
1. \(24~\text{N-s}\)
2. \(20~\text{N-s}\)
3. \(12~\text{N-s}\)
4. \(6~\text{N-s}\)
A body of mass \(M\) hits normally a rigid wall with velocity \(v\) and bounces back with the same velocity. The impulse experienced by the body is:
1. \(1.5Mv\)
2. \(2Mv\)
3. zero
4. \(Mv\)
An explosion blows a rock into three parts. Two parts go off at right angles to each other. These two are, the first part 1 kg moving with a velocity of 12 and the second part 2 kg moving with a velocity of 8 . If the third part flies off with a velocity of 4 , its mass would be:
1. 5 kg
2. 7 kg
3. 17 kg
4. 3 kg
A body, under the action of a force \(\overset{\rightarrow}{F} = 6 \hat{i} - 8 \hat{j} + 10 \hat{k}\), acquires an acceleration of 1 ms-2. The mass of this body must be:
1. 2 √10 kg
2. 10 kg
3. 20 kg
4. 10 √2 kg