Question

a car starting from rest accelerates with 5 metre per second square and reaches maximum velocity 20 metre per second then by the application of brakes it comes to rest with the acceleration of 8 metre per second square the total time journey is​

Answer 1

Answer:

Answer is 6.5 sec

Explanation:

Since car starts from rest initial velocity will be zero

We have . V=U+ at

Where "v" is final vel. And "u" is initial vel.

So, in first case

20= 0+5*t

We get time t = 4 sec

In second case initial vel. Becomes 20 m/s and final velocity becomes 0 m/s

Let time taken be "T" for this and since speed is decreasing so there is retardation (-a)

Now v=u-aT

0=20-8*T

We get T= 2.5 sec

So total distance is

t+T= 4+2.5=6.5 sec