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 m s⁻². With what force does each person push the motorcar? (Assume that all persons push the motorcar with the same muscular effort.)

Answer 1

Here, mass of the Motorcar, m = 1200 kg

Let each person exert a force F on the motorcar.

Total force of two persons = F + F = 2 F

As this force gives the motorcar a uniform velocity along a level road, it must be a measure of the force of friction (f) between the motorcar and the road, i.e., f = 2F.

When three person push, total force applied = F + F + F = 3 F

Force that produces acceleration (a = 0.2 ms^-2),

i.e., ma = 3 F - f

= 3F - 2F

= F

or F = ma

= 1200 × 0.2

= 240 N