Question

A motor car of mass 250 kg is moving with a certain velocity. It is brought to rest by the application of the brakes, within a distance of 18m when the average resistance being offered to it is 1000newton.what was the velocity of the motor car

Answer 1

Answer:

Given,

Mass of car, M=2000kg

Velocity, V=72×

18

5

=20ms

−1

Apply kinematic equation of motion

v

2

−u

2

=2as

0−20

2

=2a×20

a=−10ms

−2

Breaking force, F=ma=2000×10=20 kN

Apply first kinematic equation

v=u+at

t=

a

v−u

=

−10

0−20

=2 sec

Breaking force is 20 kNand time is 2sec.