Given below are two statements: 

Assertion (A):	Position-time graph of a stationary object is a straight line parallel to the time axis.
Reason (R):	For a stationary object, the position does not change with time.

  

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.	(A) is true but (R) is false.
4.	Both (A) and (R) are false.

The acceleration of a particle starting from rest varies with time according to the relation A = – aω²sinωt. The displacement of this particle at a time t will be:

1. $-\frac{1}{2}\left({\mathrm{a\omega }}^2\mathrm{sin\omega t}\right){\mathrm{t}}^2$

2. $\mathrm{a\omega sin\omega t}$

3. $\mathrm{a\omega cos\omega t}$

4. $\mathrm{asin\omega t}$

A thief is running away on a straight road in a jeep moving with a speed of 9 ms^–1. A policeman chases him on a motor cycle moving at a speed of 10 ms^–1. If the instantaneous separation of the jeep from the motorcycle is 100 m, how long will it take for the policeman to catch the thief?

A stone is dropped from a height h. Simultaneously, another stone is thrown up from the ground which reaches a height 4h. The two stones cross each other after time:

1. $\sqrt{\frac{h}{8g}}$

2. $\sqrt{8g}$ $h$

3. $\sqrt{2g}$ $h$

4. $\sqrt{\frac{h}{2g}}$

Four marbles are dropped from the top of a tower one after the other at a one-second interval. The first one reaches the ground after 4 seconds. When the first one reaches the ground the distances between the first and second, the second and third, and the third and fourth will be, respectively:

A particle is projected upwards. The times corresponding to height h while ascending and while descending are t₁ and t₂ respectively. The velocity of projection will be:

1. gt₁

2. gt₂

3. $g$ $(t_1+t_2)$

4. $\frac{g(t_1+t_2)}{2}$

Two cars are moving in the same direction with the same speed 30 km/hr. They are separated by a distance of 5 km. The speed of a car moving in the opposite direction, if it meets these two cars at an interval of 4 minutes, will be

1. 40 km/hr

2. 45 km/hr

3. 30 km/hr

4. 15 km/hr

Acceleration-time graph of a body is shown.

 
The corresponding velocity-time graph of the same body is: 

1.		2.
3.		4.

Which of the following velocity-time graphs shows a realistic situation for a body in motion?

1.		2.
3.		4.

Which graph represents a uniformly accelerated motion?

1.		2.
3.		4.