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Question
A block of mass 1 kg is placed at point A of a rough track shown in figure following. If slightly pushed towards right, it stops at point B of the track. Calculate the work done by the frictional force on the block during its transit from A to B.
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Solution
\[\text{ Given }, \]
\[\text{ Mass of the block, m = 1 kg }\]
\[\text{ Height of point A, H = 1 m }\]
\[\text{ Height of point B, h = 0 . 8 m }\]
Work done by friction = Change in potential energy of the body
\[\Rightarrow \text{W}_1 = \text{ mgh - mgH}\]
\[ = 1 \times 10 \left( 0 . 8 - 1 \right)\]
\[ = - 1 \times 10 \times \left( 0 . 2 \right) = - 2 \text{ J } \]
The work done by the frictional force on the block during its transit from A to B is - 2 joule.
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