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

If a train travelling at 72 kmph is to be brought to rest in a distance of 200 metres, then its retardation should be

(1) 20 ms^–2

(2) 10 ms^–2

(3) 2 ms^–2

(4) 1 ms^–2

The displacement of a particle starting from rest (at t = 0) is given by $s=6t^2-t^3$. The time in seconds at which the particle will attain zero velocity again, is  

(1) 2

(2) 4

(3) 6

(4) 8

Two cars A and B are at rest at the same point initially. If A starts with uniform velocity of 40 m/sec and B starts in the same direction with a constant acceleration of 4 m/s², then B will catch A after how much time?

(1) 10 sec

(2) 20 sec

(3) 30 sec

(4) 35 sec

The motion of a particle is described by the equation $x=a+b{t}^2$ where a = 15 cm and b = 3 cm/s². Its instantaneous velocity at time 3 sec will be 

(1) 36 cm/sec

(2) 18 cm/sec

(3) 16 cm/sec

(4) 32 cm/sec

A body travels for 15 sec starting from rest with constant acceleration. If it travels distances S₁, S₂ and S₃ in the first five seconds, second five seconds and next five seconds respectively the relation between S₁, S₂ and S₃ is 

(1) $S_1=S_2=S_3$

(2) $5S_1=3S_2=S_3$

(3) $S_1=\frac{1}{3}{S}_2=\frac{1}{5}{S}_3$  

(4) $S_1=\frac{1}{5}{S}_2=\frac{1}{3}{S}_3$

A body is moving according to the equation $x=at+b{t}^2-c{t}^3$ where x = displacement and a, b and c are constants. The acceleration of the body is 

(1) $a+2bt$ 

(2) $2b+6ct$ 

(3) $2b-6ct$ 

(4) $3b-6c{t}^2$ 

A particle travels 10 m in first 5 sec and 10m in the next 3 sec. Assuming constant acceleration what is the distance travelled in next 2 sec ?

(1) 8.3 m

(2) 9.3 m

(3) 10.3 m

(4) None of above

The distance travelled by a particle is proportional to the squares of time, then the particle travels with  

(1) Uniform acceleration

(2) Uniform velocity

(3) Increasing acceleration

(4) Decreasing velocity

Velocity of a particle changes when 

(1) Direction of velocity changes

(2) Magnitude of velocity changes

(3) Both of above

(4) None of the above