26.The time-displacement graph of a moving particle is a straight line. Then:

27.If the time-displacement graph of a particle is parallel to the time-axis, the velocity of particle is:

28.A stone is released from a hydrogen balloon, going upwards with 12 m/s. When it is at height of 65m from the ground, time the stone will take to reach the ground is:

29.A train of 150 m length is going towards north direction at a speed of 10 m/s. A parrot flies at a speed of 5 ms-1 towards south direction parallel to the railway track. The time taken by the parrot to cross the train is equal to: