Calculating Minimum Horsepower for Moving a Mass at a Given Speed

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Homework Help Overview

The discussion revolves around calculating the minimum horsepower required for a motor to move a 270 kg box at a speed of 1.20 m/s on a level surface, considering a coefficient of friction of 0.50.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the application of formulas related to force and power, with some questioning the values used in calculations. There are attempts to clarify the relationship between work, force, and power.

Discussion Status

Some participants have provided alternative approaches and formulas, while others express uncertainty about their calculations and the perceived low horsepower results. Multiple interpretations of the problem are being explored.

Contextual Notes

There is a mention of potential confusion regarding the values used in calculations, particularly the gravitational constant, and the implications of the results in a real-world context.

RileyAllen
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Homework Statement


What minimum horsepower must a motor have to be able to drag a 270 kg box along a level floor at a speed of 1.20 m/s if the coefficient of friction is 0.50?


Homework Equations


Ffr=mu*mg
W=Ffr*d


The Attempt at a Solution


I ended up having W=Fr*d=mu*m*g*d
(.5)*(270)*(1.2)*(1.2)=194.4 J/s=.26 hp

That is way too low.

Can anyone give me any guidance?
 
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It looks like you just used 1.2 instead of 9.81 in your calc, but it would be better to use P = F*v.
If you don't know this formula, it is from P = W/t = F*d/t = F*v.
 
Is the way I tried it wrong? I ended up with hp=2.13 and that still seems pretty low
 
That answer looks good!
Why does it seem low? Picture a pair of horses pulling a sled with a big guy on it at 5 km/hr?
 

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