Answer:
1747.9 J
Step-by-step explanation:
The work done to lift a book by a certain height is
where
m = 1.40 kg is the mass of one book
is the acceleration due to gravity
The first shelf is 15.0 cm (0.15 m) from the ground, and it can be filled with 28 books. So, the work done to fill the first shelf is
The 2nd shelf is 38.0 cm above the first one, so its height from the ground is
It can also contain 28 books, so the work done to fill this shelf is
The height of the third shelf is
It can also contain 28 books, so the work done to fill this shelf is
The height of the 4th shelf is
It can also contain 28 books, so the work done to fill this shelf is
The height of the 5th shelf is
It can also contain 28 books, so the work done to fill this shelf is
Therefore, the total work done is: