A car at rest has mass 1000 kg. It is moved by a horizontal force of 50 N over a horizontal surface. Calculate the work done by the force in 8 s.
If a be the acceleration of the car,
Then by Newton's second law of motion
F=ma
⇒a=Fm=501000=0.05m/s2
By second equation of motion,
S=ut+12at2
Given:
Time t=8 s
Initial velocity u=0
The displacement in 8 s is
S=0(8)+12(0.05)(8)2=1.6 m
Work done by the force in 8 s is,
W=F×S=(50 N)×(1.6 m)=80 J