Question

A 200kg car traveling to the East slows down uniformly from 20.0 m/s to 8m/s how long does it take the car to decelerate if the force on the car is 7800n

Answer 1

Given,

Mass of the car, m=200 kg

Initial velocity is u=20.0 m/s

Final velocity is v=8 m/s.

The force on the car is F=7800 N.

Let a be the decelaration,

Thus,

F=ma

a=F/m=7800/200=39

Thus the decceleartion is

`-39m/s^2`

Using the equation of kinematics,

`\begin{gathered} v=u+at \\ \Rightarrow8=20+(-39)t \\ \Rightarrow t=0.307\text{ s} \end{gathered}`

Thus,

The time required is 0.307 s.