You drop a 2.20 kg book to a friend who stands on the ground at distance D = 12.
ID: 2175328 • Letter: Y
Question
You drop a 2.20 kg book to a friend who stands on the ground at distance D = 12.0 m below. If your friend's outstretched hands are at distance d = 1.20 m above the ground (Fig. 8-30), (a) how much work Wg does the gravitational force do on the book as it drops to her hands? (b) What is the change ?U in the gravitational potential energy of the book-Earth system during the drop?
You drop a 2.20 kg book to a friend who stands on the ground at distance D = 12.0 m below. If your friend's outstretched hands are at distance d = 1.20 m above the ground (Fig. 8-30), (a) how much work Wg does the gravitational force do on the book as it drops to her hands? (b) What is the change ?U in the gravitational potential energy of the book-Earth system during the drop?Explanation / Answer
a)W=mg(12-1.2)=2.2*9.8*10.8=232.85 b)?U in the gravitational potential energy of the book-Earth system during the drop=0 [No external force. So no change in energy]