A car starts from rest, accelerate at 2m/s , for 15sec , it then continues at a steady speed for further 25sec and decelerate to rest in 5ecs . Find

Question

the time taken to cover *two-third* of the distance.

Answer 1

plot velocity vs time. first 15 seconds, v will increase steadily, then constant, then down.
The area under the velocity-time curve is distance.