The position of a particle moving in the XY plane at any time \(t\) is given by \(𝑥
=
(
3
𝑡^
2
−
6
𝑡
)\) metres. Select the correct statement about the moving particle from the following.
1. The acceleration of the particle is zero at \(t = 0\) second
2. The velocity of the particle is zero at \(t = 0\) second
3. The velocity of the particle is zero at \(t = 1\) second
4. The velocity and acceleration of the particle are never zero
If a body having initial velocity zero is moving with uniform acceleration \(8\ \text{m/s}^2\), then the distance travelled by it in the fifth second will be:
1. \(36\) metres
2. \(40\) metres
3. \(100\) metres
4. Zero
An alpha particle enters a hollow tube of \(4\ \text{m}\) length with an initial speed of \(1\ \text{km/s}\). It is accelerated in the tube and comes out of it with a speed of \(9\ \text{km/s}\). The time for which it remains inside the tube is:
1. \(8 × 10^{ − 3} \ \text{s}\)
2. \(80 × 10^{ − 3} \ \text{s}\)
3. \(800 × 10^{ − 3} \ \text{s}\)
4. \(8 × 10^{ − 4} \ \text{s}\)
Two cars \(A\) and \(B\) are travelling in the same direction with velocities \(v_1\) and \(v_2 (v_1>v_2)\). When the car \(A\) is at a distance \(d\) behind car \(B\), the driver of the car \(A\) applied the brake producing uniform retardation \(a\). There will be no collision when:
1. \(d< \dfrac{(v_1-v_2)^2}{2a}\)
2. \(d< \dfrac{v^2_1-v^2_2}{2a}\)
3. \(d> \dfrac{(v_1-v_2)^2}{2a}\)
4. \(d> \dfrac{v^2_1-v^2_2}{2a}\)
A body of mass \(10\ \text{kg}\) is moving with a constant velocity of \(10\ \text{m/s}\). When a constant force acts for \(4\ \text{s}\) on it, it moves with a velocity \(2\ \text{m/s}\) in the opposite direction. The acceleration produced in it is:
1. \(3\ \text{m/s}^2\)
2. \(-3\ \text{m/s}^2\)
3. \(0.3\ \text{m/s}^2\)
4. \(-0.3\ \text{m/s}^2\)
A body starts from rest from the origin with an acceleration of \(6~\text{m/s}^2\) along the \(x\text-\)axis and \(8~\text{m/s}^2\) along the \(y\text-\)axis. Its distance from the origin after \(4\) seconds will be:
1. \(56~\text{m}\)
2. \(64~\text{m}\)
3. \(80~\text{m}\)
4. \(128~\text{m}\)
A car moving with a velocity of \(10\ \text{m/s}\) can be stopped by the application of a constant force \(F\) in a distance of \(20\ \text{m}\). If the velocity of the car is \(30\ \text{m/s}\), it can be stopped by this force in:
1. \(\dfrac {20}{3} \ \text{𝑚}\)
2. \(20\ \text{m}\)
3. \(60\ \text{m}\)
4. \(180\ \text{m}\)
The displacement of a particle is given by \(y = a + bt + ct^{2} - dt^{4}\). The initial velocity and acceleration are, respectively:
| 1. | \(b, -4d\) | 2. | \(-b,2c\) |
| 3. | \(b, ~2c\) | 4. | \(2c, -2d\) |
A car moving with a speed of \(40\ \text{km/h}\) can be stopped by applying the brakes for at least \(2\ \text{m}\). If the same car is moving with a speed of \(80\ \text{km/h}\), what is the minimum stopping distance?
1. \(8\ \text{m}\)
2. \(2\ \text{m}\)
3. \(4\ \text{m}\)
4. \(6\ \text{m}\)
An elevator car, whose floor-to-ceiling distance is equal to \(2.7~\text{m}\), starts ascending with constant acceleration of \(1.2~\text{ms}^{-2}\). \(2\ \text{s}\) after the start, a bolt begins falling from the ceiling of the car. The free-fall time of the bolt is:
1. \(\sqrt{0.54}~\text{s}\)
2. \(\sqrt{6}~\text{s}\)
3. \(0.7~\text{s}\)
4. \(1~\text{s}\)