Minimum Horsepower for Dragging a Box at a Given Speed

[engineer2010]

Quick help with Power problem!

Homework Statement

What is the minimum horse power a motor must have to be able to drag a 310 kg box along a level floor at a speed of 1.2 m/s if the coefficient of friction is .45

Homework Equations

fg=mg - - - > (c of f) (fn)= Ff
P = Fv

The Attempt at a Solution

I found Ff to be 1367 N but I am unsure of how to find the force with the motor is putting on the box.. I know that the box is not acclerating. so i tried going -1367 +F= 0 and the putting that in the power formula but that did not give me the correct answer

 

[hage567]

Are you remembering to convert it from watts to horsepower?

 

[engineer2010]

ok i got it thanks.. i was thinking that there was another force in addition to the 1367. but i figured it out.