Question

A truck on a straight road starts from rest and accelerates at 1.4 m/s 2 until it reaches a speed of 22 m/s. Then the truck travels for 22 s at constant speed until the brakes are applied, stopping the truck in a uniform manner in an additional 4.4 s. How long is the truck in motion?

Answer 1

Answer:

42.11 sec

Explanation:

In first part : The truck start from the rest that is u = 0 m/sec

Acceleration is given as $a=1.4m/sec^2$

It reaches to a velocity of 22 m/sec so v=22 m/sec

Now according to first law of motion $v=u+at$

$22=0+1.4\times t$

$t=15.71sec$

In second part : The truck maintain a constant speed for 22 sec

In third  part : The truck takes an additional 4.4 sec for stopping

So total time in which the truck is in motion =15.71+22+4.4=42.11 sec