Question

A car mass 100 KG is moving with a velocity 90 Km/h.What is the force required to stop the car in 10 seconds is

Answer 1

See the attachment.............

The values of v and u are interchanged. On correction the force would come out to be negative because it is acting opposite to the direction of motion

Answer 2

Answer:

The force required to stop the car in 10 seconds is 250N.

Explanation:

We will use the first equation of motion to solve this question,

$v=u+at$             (1)

Where,

v=final velocity

u=initial velocity

a=acceleration

t=time

As per the question we have,

v=0

u=90km/hr=90×5/18=25m/s

t=10 seconds

m=100kg

By substituting the required values in equation (1) we get;

$0=25+a\times 10$

$a=\frac{-25}{10}=\frac{-5}{2} ms^-^2$              (2)  

∴ Here the negative sign in acceleration just shows that it is decreasing.

And we know,

$Force=m\times a$    (3)

m=mass of the body

a=acceleration of the body

By substituting the values in equation (3) we get;

$Force=100\times \frac{5}{2}=250N$

Hence, the force required to stop the car in 10 seconds is 250N.