Question

A motorcycle is moving with a velocity of 90km\hour and it takes 5 sec to stop after the breaks are applied.Calculate the force exerted by the breaks on the motorcycle if it's mass along with the rider is 200 kg

Answer 1

Speed in km/hr × 5/18 = Speed in m/sec

And three Equation of Motion i.e.
v = u + at
s = ut + 1/2 a t^2
v^2 = u^2 + 2as

Force = Mass × Acceleration
_______________________________

Initial velocity = 90 km/hr
Initial velocity in m/sec(v) = 90 × 5/18
Initial velocity (u) = 25 m/sec

Time (t) = 5 seconds

Final Velocity (v) = 0 because motorcycle is at rest finally

Using First equation of Motion,
v = u + at
0 = 25 + a × 5
-25 = 5a

a = -5 m/sec ^2

=> Retardation = 5 m/sec ^2
_____________________________

Retarding Force = Mass × Retardation

Retarding Force = 200 × 5

Retarding Force = 1000 N