Question

A car moving with a speed of 108 km/h come to rest after 4s on applying brake. If the mass of the car along with the passenger inside is 1000kg what will be the force applied when break is applied​

Answer 1

u= 108 km/hr=30m/sec

V=0 m/sec

t=4sec

a=v-u/t

a=0-30/4

a=-30/4

now,

F=MA

F= 1000*(-30/4)

F=-7500N

Answer 2

Answer:

Force=mass*acceleration

f=m×

t

v−u

f=1000×

4

0−108×

18

5

=1000×(−7.5)

∴f=−7500N

opposing force is denoted by negative sign.