## Work Done By a Gravitational Force

Hi, I'm having trouble understanding this concept. A refrigerator is on a ramp of length d and it is being pushed up the ramp. What is the work done by the gravitational force? In the book it says mgdcos180 which is -mgd. I thought that the horizontal component of gravity was mgsin(theta) so the work done would by (mgsin(theta))(d)(cos180).

Also, is work done by the gravitational force difference than gravitational potential energy?

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 Quote by xdarkelf714x Hi, I'm having trouble understanding this concept. A refrigerator is on a ramp of length d and it is being pushed up the ramp. What is the work done by the gravitational force? In the book it says mgdcos180 which is -mgd. I thought that the horizontal component of gravity was mgsin(theta) so the work done would by (mgsin(theta))(d)(cos180).
Assuming that d is the distance along the ramp and not the height, then you're correct. In terms of height (h), the work done by gravity is just F*S = -mgh, which is equivalent to -mgdsin(theta).

 Also, is work done by the gravitational force difference than gravitational potential energy?
Same thing (just opposite sign).
 Oh, I see it now. Thank you for clearing that up for me.