Calculating Work Done by Friction

AI Thread Summary
To calculate the work done by friction while pushing a refrigerator, the correct formula is W = F × d, where F is the force and d is the distance moved. The initial calculation used an incorrect equation for power instead of work, leading to an erroneous result of 124 J. Since the refrigerator moves at a constant velocity, the work done by friction equals the negative of the applied force multiplied by the distance. Therefore, the correct approach involves using the force of friction, which matches the applied force of 297 N over the distance of 2.8 m. The final work done by friction is -834 J, indicating that friction opposes the motion.
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Homework Statement



You are pushing a refrigerator across the floor of your kitchen. You exert a horizontal force of 297 N for 6.7 s, during which time the refrigerator moves a distance of 2.8 m at a constant velocity.

What is the work done by friction?

Homework Equations



W=fv
w=f(d/t)

The Attempt at a Solution



w=297(2.8/6.7) = 124 J.

Why is this answer incorrect?
Any info to the right direction is much help :) thanks
 
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Edit - Right, it'll be -FΔx.

Thanks.
 
Last edited:

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
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Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
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