Question.
Two persons manage to push a motorcar of mass 1200 kg at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of 0.2 ms–2. With what force does each person push the motorcar ? (Assume that all persons push the motorcar with the same muscular effort.)
Two persons manage to push a motorcar of mass 1200 kg at a uniform velocity along a level road. The same motorcar can be pushed by three persons to produce an acceleration of 0.2 ms–2. With what force does each person push the motorcar ? (Assume that all persons push the motorcar with the same muscular effort.)
Solution:
As two persons can make the motorcar move with uniform velocity, it is clear that total force
applied by them on the motorcar is balanced by the force of friction acting in the opposite
direction. It is force of one more person which produces an acceleration of $0.2 \mathrm{~ms}^{-2}$.
$\therefore$ Force of one person $=$ mass $\times$ acceleration $=1200 \times 0.2=240 \mathrm{~N}$
As two persons can make the motorcar move with uniform velocity, it is clear that total force
applied by them on the motorcar is balanced by the force of friction acting in the opposite
direction. It is force of one more person which produces an acceleration of $0.2 \mathrm{~ms}^{-2}$.
$\therefore$ Force of one person $=$ mass $\times$ acceleration $=1200 \times 0.2=240 \mathrm{~N}$