Question

A constant force of friction of 50 N is acting on a body of mass 200 kg moving initially with a speed of 15 m/s. How long does the body take to stop? What distance will it cover before coming to rest?

Answer 1

Given, F = 50 N, m = 200 kg, u = 15 m/s The acceleration of the body is obtained from F = m . a

or,   a = F m = 50 /200 = - 0.25 m/s2
Now, from the first equation of motion

     v = u + at

 = 60 s
Also, distance travelled is obtained from s = ut + 1 /2 at2
   = 50 × 60 +1/2 × (-0.25) (60)2 = 450 m