A 1.4 kg book is lying on a 0.80 m-high table. You pick it up and place it on a bookshelf 2.2 m above the floor.
1) How much work does your hand do on the book?
2.) How much work does gravity do on the book? [solved]
The Attempt at a Solution
Ok. I was able to find the displacement to be 1.4 m. Since acceleration due to gravity is 9.8 (and negative in this case) i multiplied it by the mass 1.4 kg to get the force. Then I took the answer (-13.7) and multiplied that by the displacement which gave me the correct answer of -19 J.
The problem is that I', not sure how to find the amount of work the hand does on the book. The displacement is the same, but I don't know how to find the force. Any help would be appreciated.