Question

A car starts from rest and retains the acceleration of 4mls in 20 second .calculate its final velocity
step by step​

Answer 1

Given that,

Acceleration a=2m/s  

2

 

Retardation a=−3m/s  

2

 

Time t=10s

Now, from equation of motion

The maximum velocity attained be v at t  

 v=u+at

v=0+2×t

v=2tm/s.....(I)

Now, again it reaches velocity 0 after 10 s with retardation

 v=u+at

0=v−3(10−t)

Now from equation (I)

 2t−3(10−t)=0

2t−30+3t=0

5t=30

t=6s

Now, put the value of t in equation (I)

 v=2t

v=2×6

v=12m/s

Hence, the maximum speed is 12 m/s

Answer 2

Answer:

Explanation:

use a= v-u/t