Question

1. A car of mass 200 kg is moving with a speed of
36km/h comes to rest after application of break in
20 sec. Find the net force applied by the brake. ​

Answer 1

Given:-

→Mass of the car=200kg

→Initial velocity of the car=36km/h

→Time=20sec

To find:-

•Net force applied by the brake

Solution:-

Firstly,let us convert the initial velocity of the car from km/h to m/s.

=>1km/h=5/18 m/s

=>36km/h=36×5/18

=>10m/s

Also,the final velocity of the car will be zero as it finally comes to rest after application of brakes.

By using Newton's 2nd law of motion,we get:-

=>F=m(v-u)/t

Where:-

•F is net force

•m is mass of the body

•v is final velocity of the body

•u is initial velocity of the body

•t is time taken

=>F=200(0-10)/20

=>F=200(-0.5)

=>F= -100N

Here,- sign represents retarding force.

Thus,net retarding force applied by the brake is 100N.