Question
A force acts for 8 seconds on a body of mass 10 kg. The force then stops acting and the body describes 80 m in next 5 sec. Find the force.
Solution
Here,
Mass, m = 10 kg; t = 8 sec
After the force stops acting, the body moves with a uniform velocity given by,
v = 
Initial velocity of the body, u = 0
Using equation of motion,
v = u + at
16 = 0 + a x 8
a = 2 m/s2
Therefore,
Force, F = ma = 10 
= 20 N
