**A 1.1 kg book is lying on a 0.74 m-high table. You pick it up and place it on a bookshelf 2.2 m above the floor.**

**How much work does gravity do on the book?**

**Known variables:**

**mass (m):**

**height 1 (h1): .74 m**

**height 2 (h2): 2.2m**

**Height difference: 2.2** – .74= 1.46

displacement x force:

mass x gravity x height

1.1kg*9.8*1.46 = 17.6 J

Since gravity is forcing down, it would be negative!

**W1=** -17.6

**2) How much work does your hand do on the book?**

Same answer as the previous question but a positive force.

W2= 17.6

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