Q21 of 42 Page 33

A block placed on a rough horizontal surface is pulled by a horizontal force F. Let f be the force applied by the rough surface on the block. Plot a graph of f versus F.

Let f (frictional force) at y-axis and F at x-axis


Now when a small force F1 is applied on a heavier box, this box does not move, at this state, force of friction f1 is equal to F1. Increasing force on box does not move till F = fs (the maximum static frictional or limiting force).


After force fs, the frictional force decrease i.e. less kinetic force Fk<fs is applied on body and it starts to move with less friction


In diagram A is equivalent to limiting frictional force and a B is equivalent to kinetic frictional force.


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