A metal block is moved in two stages: first it is lifted slowly from the ground to…

PHYSICS · Multi-part · CBSE · Physics · Work and Energy · Work and Energy

Problem

2.0\,\text{kg}

metal block is moved in two stages: first it is lifted slowly from the ground to the top of a table

5.0\,\text{m}

high, and then it is carefully lowered to a stool that is

2.0\,\text{m}

above the ground level. Assume the acceleration due to gravity to be

9.8\,\text{m s}^{-2}

. (i) Calculate the work done by the gravitational force while the block is raised from

0

5.0\,\text{m}

. (ii) Calculate the work done by the gravitational force while the block is lowered from

5.0\,\text{m}

2.0\,\text{m}

. (iii) Find the total work done by the gravitational force for the complete motion from the ground to the stool and comment on its sign.