A 2.0kg metal block is moved in two stages: first it is lifted slowly from the ground to the top of a table 5.0m high, and then it is carefully lowered to a stool that is 2.0m above the ground level.
Assume the acceleration due to gravity to be 9.8m s−2.
a. (i) Calculate the work done by the gravitational force while the block is raised from 0 to 5.0m.
b. (ii) Calculate the work done by the gravitational force while the block is lowered from 5.0m to 2.0m.
c. (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.