Calculating Work Done by Gravity on a Moved Book

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To calculate the work done by gravity on a book lifted from a height of 0.99 m to 2.43 m, the correct approach involves using the equation Wmg = mg(Yi - Yf). The initial poster initially misapplied the equation, mistakenly calculating the work done by their hands instead of gravity. The key realization was that the work done by gravity is negative when lifting the book, as gravity opposes the motion. Correcting the sign in the equation resolves the confusion. Understanding the distinction between the work done by gravity and the work done by the person lifting the book is crucial for accurate calculations.
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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


Homework Equations


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?
 
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talaroue said:

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


Homework Equations


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

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