The position of a particle moving along the x-axis given by $x=\left(-2t^3+3t^2+5\right)m$. The acceleration of a particle at the instant its velocity becomes zero is

(1) 12 m/s²

(2) -12 m/s²

(3) -6  m/s²

(4) Zero

A particle moves with velocity \(v_1\) for time \(t_1\) and \(v_2\) for time \(t_2\) along a straight line. The magnitude of its average acceleration is:
1. $\frac{v_2-v_1}{t_1-t_2}$
2. $\frac{v_2-v_1}{t_1+t_2}$
3. $\frac{v_2-v_1}{t_2-t_1}$
4. $\frac{v_1+v_2}{t_1-t_2}$

A particle starts moving with acceleration 2 m/s². Distance travelled by it in 5^th half-second is-

(1) 1.25 m

(2) 2.25 m

(3) 6.25 m

(4) 30.25 m

The two ends of a train moving with constant acceleration pass a certain point with velocities u and 3u. The velocity with which the middle point of the train passes the same point is

(1) 2u

(2) $\frac{3}{2}u$

(3) $\sqrt{5}u$

(4) $\sqrt{10}u$

A train starts from rest from a station with acceleration 0.2 m/s² on a straight track and then comes to rest after attaining maximum speed on another station due to retardation 0.4 m/s². If total time spent is half an hour, then the distance between two stations is- [Neglect length of train]

(1) 216 km

(2) 512 km

(3) 728 km

(4) 1296 km

A body is projected vertically in the upward direction from the surface of the earth. If the upward direction is taken as positive, then the acceleration of the body during its upward and downward journey is:

A particle starts moving from rest state along a straight line under the action of a constant force and travel distance x in first 5 seconds. The distance travelled by it in the next five seconds will be

(1) x

(2) 2x

(3) 3x

(4) 4x

A body is projected vertically upward with a speed 40 m/s. The distance travelled by the body in the last second of the upward journey is [take g = 9.8 m/s² and neglect effect of air resistance]

(1) 4.9 m

(2) 9.8 m

(3) 12.4 m

(4) 19.6 m

A body is projected vertically upward with a speed 10 m/s and another at the same time with the same speed in the downward direction from the top of a tower. The magnitude of acceleration of first body with respect to second is {take g = 10 m/s²}

(1) Zero

(2) 10 m/s²

(3) 5 m/s²

(4) 20 m/s²

A car travelling at a speed of \(30\) km/h is brought to rest at a distance of \(8\) m by applying brakes. If the same car is moving at a speed of \(60\) km/h, then it can be brought to rest with the same brakes in:
1. \(64\) m
2. \(32\) m
3. \(16\) m
4. \(4\) m