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Work done by friction Help! 
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#1
Oct110, 04:53 PM

P: 63

I have a physics teacher who is unable to explain anything if his life depended on it hence I am really struggling with physics. I am left out on a limb literally  at my wits end.
I have this question that I have no idea where to start with. 2 villans slid a laundry basket containing a body a distance of 7.76m across a warehouse floor. They both exerted equal horizontal forces of 319N in order to keep the basket moving at a constant velocity of 1.52m/s. How much work was done by friction? Please explain to me step by step why we get to the answer please don't just give me the equations and the answer I need to understand why we get there. I did math 20 years ago so its a whole new ball game for me. Thanks 


#2
Oct110, 05:10 PM

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P: 40,730

What are the relevant equations for calculating work from force and distance? What is the total force in this question? What is the distance? 


#3
Oct110, 05:24 PM

P: 63

Thanks
W = F*d cos theta total force is 638 distance is 7.65m 


#4
Oct110, 05:27 PM

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P: 40,730

Work done by friction Help!



#5
Oct110, 05:29 PM

P: 63

theta and cos theta (I think) should be 0 because they are parallel?
I did do this and got an answer of 4880.7 Joules  should be negative because friction is going in the opposite direction. their answer is 4.95 KJ even if I divide by 1000 I still don't get the right answer. 


#6
Oct110, 05:36 PM

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P: 40,730

BTW, you should have said theta = 0, so cos(0) = 1. That must be what you meant, since you would have gotten the right answer without the distance typo. Good job. 


#7
Oct110, 05:40 PM

P: 63

thanks a mil  sometimes you just need guidance to get your confidence and when you have been looking at it for hours without success it gets harder and harder.



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