Question

A car has velocity of 162 km/h and mass of 900 kg it takes 5 sec for car to come at rest find force applied on the car

Answer 1

Answer:

8100 N

Explanation:

First we need to bring the velocity of the car from km/hr to m/s

ie. 162 x 1000/3600

=  45 m/s

Therefore, v = 45 m/s

                 t = 5 s

                 u = 0 m/s ( at rest )

a = v - u / t

  = 45 - 0 / 5

   = 9 m/s²

As F = ma

 Force = 900 x 9

            = 8100 N

Answer 2

Answer:

-8100 N

Explanation:

Given:

Initial velocity = u = 162 km/h

162 km/h =$162 \times \frac{5}{18} = 45 \ m/s$

Final velocity = v = 0 m/s

Time = t = 5 seconds

Mass of the car = 900 kg's

To find:

Force applied on the car

Force = $\frac{m(v-u)}{t}$

Force =$\frac{900(0-45)}{5}$

Force = $\frac{900 \times -45}{5}$

Force = -8100 N

The force applied to stop the car is equal to -8100 Newtons in the direction of the motion of the car