Q. No.A particle moves along a straight line such that its displacement at any time t is given by metres. The velocity when the acceleration is zero is:
1.
4 ms-1
2.
−12 ms−1
3.
42 ms−1
4.
−9 ms−1
The position \(x\) of a particle varies with time \(t\) as \(x=at^2-bt^3\). The acceleration of the particle will be zero at time \(t\) equal to:
1. \(\frac{a}{b}\)
2. \(\frac{2a}{3b}\)
3. \(\frac{a}{3b}\)
4. zero
A student is standing at a distance of 50 metres from the bus. As soon as the bus begins its motion with an acceleration of 1 ms–2, the student starts running towards the bus with a uniform velocity u. Assuming the motion to be along a straight road, the minimum value of u, so that the student is able to catch the bus is:
1. 5 ms–1
2. 8 ms–1
3. 10 ms–1
4. 12 ms–1
If the velocity of a particle is given by m/s, then its acceleration will be:
1. Zero
2. 8 m/s2
3. – 8 m/s2
4. 4 m/s2
A body is thrown vertically upwards. If the air resistance is to be taken into account, then the time during which the body rises is:
| 1. | Equal to the time of fall |
| 2. | Less than the time of fall |
| 3. | Greater than the time of fall |
| 4. | Twice the time of fall |
A body starts to fall freely under gravity. The distances covered by it in first, second and third second will be in the ratio:
1. 1 : 3 : 5
2. 1 : 2 : 3
3. 1 : 4 : 9
4. 1 : 5 : 6
A body is thrown vertically up from the ground. It reaches a maximum height of 100 m in 5 seconds. After what time will it reach the ground from the position of maximum height?
1. 1.2 sec
2. 5 sec
3. 10 sec
4. 25 sec
If a body is thrown up with the velocity of 15 m/s, then the maximum height attained by the body is: (assume g = 10 m/s2)
1. 11.25 m
2. 16.2 m
3. 24.5 m
4. 7.62 m
If a freely falling body travels in the last second a distance equal to the distance travelled by it in the first three seconds, the time of the travel is:
1. 6 sec
2. 5 sec
3. 4 sec
4. 3 sec
A particle moving in a straight line covers half the distance with a speed of \(3~\text{m/s}\). The other half of the distance is covered in two equal time intervals with speeds of \(4.5~\text{m/s}\) and \(7.5~\text{m/s}\) respectively. The average speed of the particle during this motion is:
1. \(4.0~\text{m/s}\)
2. \(5.0~\text{m/s}\)
3. \(5.5~\text{m/s}\)
4. \(4.8~\text{m/s}\)
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