Question

a vehicles starting from rest to 72 km/h after covering a distance of 100 m . If the mass of the vehicle is 500 . find the force exerted by the engine?

Answer 1

Initial velocity = 0 m/s

Final velocity = 72 km/h = 72*5/18 m/s

= 20 m/s

distance covered , s = 100 m

let a be the accleration of the body

As v^2 - u^2 = 2as

so, 20^2 - 0^2 = 2a * 100

or, 400/200 = a

so, a = 2 m/s^2

Now, as mass,m = 500 kg

a = 2 m/s

and Force, F = ma

so, force exerted by the engine = 500 * 2

= 1000 kg m/s^2

= 1 kN

Answer 2

Explanation:

v=72km/h=72*5/18=20m/s

u=0 s=100m

v^2-u^2=2as

a=v^2-u^2/2s

=20^2-0^2/2*100

=400-0/200

=400/200

=2m/s^2

m=500kg

a=2m/s^2

F=ma

=500*2

=1000N