Question

car
Calculate the Impulse necessary to stop a 2000kg
travelling at 72 kmph.​

Answer 1

Explanation:

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.

Answer 2

Explanation:

impulse is numerically equal to change in momentum.

to stop the car, you need to make its momentum zero.

72kmph= 20m/s

therefore,

impulse= 2000(20) - 2000(0)

=> impulse= 400000N.