Curious about Work done by Gravitational force

AI Thread Summary
The discussion clarifies the relationship between gravitational force and the use of cosine in calculating work done. It emphasizes that the choice between sine and cosine depends on how the angle is defined in relation to the components of the force in a free body diagram. The reference frame does not directly influence this choice, but rather the specific orientation of the angle concerning the force vector. Participants express gratitude for the clarification, indicating a better understanding of the concept. Understanding the geometric relationships in physics is crucial for applying the correct equations.
Selectron09
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Homework Statement


I don’t understand why this would relate to cosine and not sine, if gravity is often assiciated in the up and down part of a free body diagram.

Homework Equations

Wg=mgdcos(theta)[/B]

The Attempt at a Solution


Is it because it would depend on your reference frame?
 
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Hi Selectron09,

Welcome to Physics Forums.

Selectron09 said:
Is it because it would depend on your reference frame?
Not really. It depends upon how the angle in question is defined; which "corner" of the right angle triangle is located with respect to the leg that represents your ##mgd##.

upload_2018-10-27_12-37-55.png
 

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Likes CWatters and Selectron09
Oh! Ok that clears things up a lot. Thankyou.
 
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