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(a) How much work W g doesthe gravitational force do on the book as it drops to

ID: 1675092 • Letter: #

Question

(a) How much work Wg doesthe gravitational force do on the book as it drops to herhands?
1 J

(b) What is the change U in the gravitationalpotential energy of the textbook-Earth system during the drop?
2 J

(c) If the gravitational potential energy of that system is zero atground level, what is its potential energy U when thetextbook is released?
3 J

(d) If the gravitational potential energy of that system is zero atground level, what is its potential energy U when thetextbook reaches the hands?
4 J

(e) How much work Wg is done on the textbook byits weight as it drops to your friend's hands if U is 100J at the ground level.
5 J

(f) What is the change U in the gravitationalpotential energy of the textbook-Earth system during the drop ifU is 100 J at the ground level.
6 J

(g) Find U at the release point when U is 100 Jat the ground level.
7 J

(h) Find U at the hands when U is 100 J at theground level.
8 J

Explanation / Answer

1. work by gravity = mgh = 1.50 *9.80* (10 - 1.5) =    124.95J . 2. U = negative of work done by grav =   -124.95J . 3. U = mgh = 1.50 * 9.80 *10.0 =   147J . 4. U = mgh = 1.50 * 9.80 * 1.50 =   22.05J .