Question

The block is moved from A to C along three different paths. Find the Work done by friction when the block is displaced from A to B and then from B to C.

• A. $W=-\mu mg(a+b)$
• B. $W=-\mu mg$
• C. $W=-\mu mg(a+b)/2$
• D. None of the above
  

Answer 1

The correct option is A $W=-\mu mg(a+b)$

Given:

$f=\mu N$

$N=mg$

$\theta$ is the angle between frictional force and displacement.

$\theta ={180}^0$

$\therefore \cos {180}^0=-1$

Since, frictional force is dependent on the distance travelled.

Hence, work done by force, $W=(-\mu mg)(a+b)$