Question

A block of mass 20 Kg slides over a horizontal distance of 1 m . if the coefficient of friction between their surface is 0.2, then the work done against the frictional force is ?

Answer 1

Work done against frictional force = -40J

Solution :

✴ Given :-

• Mass of block = 20kg
• Distance covered by block = 1m
• Co-efficient of friction between block and horizontal surface = 0.2

✴ To Find :-

• Work done against frictional force

✴ Formula :-

▪ Formula of work done in terms of force and displacement is given by

$\circ\bf\:W=F_fd\cos\theta\\ \\ \circ\bf\:W=(\mu\times N)d\cos180\degree\\ \\ \circ\underline{\bf\:W= -\mu{(mg}d)}$

✴ Calculation :-

$\mapsto\sf\:W=-(0.2\times 20 \times 10 \times 1)\\ \\ \mapsto\underline{\underline{\orange{\bf{Work=-40\:J}}}}$

✴ Additional information :-

• Work done by frictional force is always negative.
• Work done is a scalar quantity.