Question

A block of mass 1 kg is placed at the point A of a rough track shown in figure. If slightly pushed towards right, it stops at the point B of the track. Calculate the work done by the frictional force on the block during its transit from A to B.

• A. 2 J
• B. -2J
• C. 4 J
• D. -4 J

Answer 1

The correct option is B

-2J

$W_{net}=\Delta K.E$.

$\Delta KE=0$ as it begins and ends at rest.

$W_{net}=W_{gravity}+W_{friction}=0$

$\Rightarrow W_{gravity}+W_{friction}=0$

$\Rightarrow -W_{gravity}=W_{friction}$

$W_{friction}=-1\left(10\right)\left(0.2\right)$

As changes in height is 0.2m

$\Rightarrow -2J$