The position-time \((x\text-t)\) graphs for two children \(A\) and \(B\) returning from their school \(O\) to their homes \(P\) and \(Q\) respectively are shown in the graph.
Choose the incorrect statement:
1. | \(B\) reaches home faster than \(A.\) |
2. | \(B\) overtakes \(A\) on the road twice. |
3. | \(B\) walks faster than \(A.\) |
4. | \(A\) lives closer to the school than \(B.\) |
A jet airplane travelling at the speed of \(500~\text{km/h}\) ejects its products of combustion at the speed of \(1500~\text{km/h}\) relative to the jet plane. What is the speed of the latter with respect to an observer on the ground?
1. \(1000~\text{km/h}\)
2. \(500~\text{km/h}\)
3. \(1500~\text{km/h}\)
4. \(2000~\text{km/h}\)
A car moving along a straight highway at a speed of \(126~\text{km/h}\) is brought to a stop within a distance of \(200~\text{m}.\) How long does it take for the car to stop?
1. \(10.2~\text{s}\)
2. \(9.6~\text{s}\)
3. \(11.4~\text{s}\)
4. \(6.7~\text{s}\)
Two trains \(A\) and \(B\) of length \(400~\text m\) each are moving on two parallel tracks with a uniform speed of \(72~\text{km/h}\) in the same direction with \(A\) ahead of \(B.\) The driver of \(B\) decides to overtake \(A\) and accelerates by \(1~\text{m/s}^2.\) If after \(50~\text s,\) the guard of \(B\) just brushes past the driver of \(A,\) what was the original distance between them?
1. \(2000~\text m\)
2. \(2250~\text m\)
3. \(1200~\text m\)
4. \(1250~\text m\)
On a two-lane road, car \(A\) is travelling at a speed of \(36~\text{kmh}^{–1}.\) Two cars \(B\) and \(C\) approach car \(A\) in opposite directions with a speed of \(54~\text{kmh}^{–1}\) each. At a certain instant, when the distance \(AB\) is equal to \(AC,\) both being \(1~\text{km},B\) decides to overtake \(A\) before \(C\) does. What minimum acceleration of car \(B\) is required to avoid an accident?
1. \(1~\text{ms}^{-2}\)
2. \(5~\text{ms}^{-2}\)
3. \(2~\text{ms}^{-2}\)
4. \(3~\text{ms}^{-2}\)
A player throws a ball upwards with an initial speed of \(29.4 \text{ ms}^{- 1}.\) What is the direction of acceleration during the upward motion of the ball?
1. Vertically downwards
2. Vertically upwards
3. First upwards then downwards
4. None of the above
A particle in one-dimensional motion:
1. | with zero speed at an instant may have non-zero acceleration at that instant. |
2. | with zero speed may have non-zero velocity. |
3. | with constant speed, must have non-zero acceleration. |
4. | with a positive value of acceleration must be speeding up. |
A man walks on a straight road from his home to a market \(2.5\) km away with a speed of \(5\) km/h. Finding the market closed, he instantly turns and walks back home with a speed of \(7.5\) km/h. What is the magnitude of the average velocity of the man over the interval of time \(0\) to \(30\) min?
1. | \(6\) km/h | 2. | \(5\) km/h |
3. | \(5.6\) km/h | 4. | \(6.6\) km/h |
The instantaneous speed is always:
1. | less than the magnitude of instantaneous velocity. |
2. | greater than the magnitude of instantaneous velocity. |
3. | equal to the magnitude of instantaneous velocity. |
4. | may be less or greater than the magnitude of instantaneous velocity. |
A police van moving on a highway with a speed of fires a bullet at a thief’s car speeding away in the same direction with a speed of . If the muzzle speed of the bullet is with what speed does the bullet hit the thief’s car?