Answer:
Work done to move the block from bottom to top is 400 J
Step-by-step explanation:
Work is done against gravity here to move the book from floor to the top
So here work done is given as
W = mgH
here we know that
mg = 20 N
also we know that
H = 20 m
so we have
W = 20(20) J
![W = 400 J](https://img.qammunity.org/2021/formulas/physics/middle-school/7j1am3x512lkv0b29ymbydydwi7dwu4w3g.png)