# Book on table moved to Shelf

talaroue

## Homework Statement

A 1.7 kg book is lying on a 0.99-m-high table. You pick it up and place it on a bookshelf 2.43 m above the floor.
How much work does gravity do on the book

Wmg=mgYi-mgYf

## The Attempt at a Solution

I thought that is the correct equation so I simply just plugged and chugged but it came out wrong. What did I do wrong?

Mentor

## Homework Statement

A 1.7 kg book is lying on a 0.99-m-high table. You pick it up and place it on a bookshelf 2.43 m above the floor.
How much work does gravity do on the book

Wmg=mgYi-mgYf

## The Attempt at a Solution

I thought that is the correct equation so I simply just plugged and chugged but it came out wrong. What did I do wrong?

It might just be a sign error. Note that the question asks for the work done by gravity on the book. But the postive work done is by the person lifting the book...

talaroue
Sorry guys I jumped the gun on this one. I soon realized that I just had to reverse my orginal equation. The equation that I have is for the work done by your hands picking the book up.

talaroue
I just posted as you posted yeah, thanks for the help!