Question

A car starting from rest attains a velocity of 125/9 m/s and travels 250km. What is the acceleration of the body?​

Answer 1

s=9km=9000m

This motion is in three phases.

[Case: 1]

with acceleration, a=0.2ms−2 and  intial velocity , u=0

Thus using equation v=u+at

10=0+0.2×t

So, t=50 s

[Case: 2]

uniform motion with velocity ,v=10 

and distance, s=9000

Thus time , t=vs=109000=900 s

[Case: 3]

With acceleration, a=−0.1ms−2

u=10ms−1

and v=0

Thus using equation v=u+at

0=10−0.1×t

So, t=0.110=100 s

Therefore

Total time = 50s+900s+100s=1050s