The diagram shows the velocity-time graph of two moving cars P and Q. The graph indicates that

Options

A. The velocity of car P is increasing at a decreasing rate from 40 s to 45 s in same direction.
B. Car Q is moving with a constant acceleration from 0 to 40 seconds
C. Acceration of the car Q is not zero at any point during whole journey .
D. After 20 s, P is bihind Q.

Answer

A

Explanation

From 40 s to 45 s direction of car P is same but velocity is increasing at a decreasing rate of accleration .
(ii) Acceleration of car Q from 0 to t seconds is
`(50-0)/(20-0) = 2.5 m s^(-2) ` i.e., constant and after t is becomes zero.
(iii) Acceleration of the car Q is zero from t to 70 s , so velocity is constant.
(iv) Distance travelled by P at the end of first 20 s `= 1/2 xx 50 xx (10+ 20) = 750 m`
Distance travelled by Q at the end of first 20 s `= 1/2 xx 50 xx 20 = 250 m`
After 20 s , Q is behind P by 250 m