Gravity Work: Lifting 10N Book 1m at 0.5m/s

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SUMMARY

The discussion centers on the calculation of work done by gravity when lifting a 10N book a distance of 1 meter at a constant velocity of 0.5 m/s. The key conclusion is that the work done by gravity in this scenario is zero, as gravity does not perform work when there is no displacement in the direction of the gravitational force. The relevant equations discussed include W=FD for work and Wg=mgh for gravitational work, highlighting the importance of displacement in determining work done.

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Oxygen206
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Homework Statement


The problem asks, "You lift a 10N book up in the air a distance of 1m at a constant velocity of 0.5m/s. The work done by gravity is:

a. -10J
b.-5J
c. zero
d. 5J
e. 10J


Homework Equations


W=FD
Wg=mgh


The Attempt at a Solution


So, the work done by whoever is lifting the book is 10J (W=FD) but with the hand still holding the book, is gravity doing work? I just really can't decide if gravity is doing "work" in this situation. Can someone point me in the right direction? Thank you!
 
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Oxygen206 said:
but with the hand still holding the book, is gravity doing work? I just really can't decide if gravity is doing "work" in this situation. Can someone point me in the right direction? Thank you!

The definition of work involves a distance as you pointed out. If the book is on the ground, does the gravity do work? As it is not moving, no.
By the way the definition of work can be found there : https://www.physicsforums.com/library.php?do=view_item&itemid=75. It's a line integral.
 

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