A 165N sled is pulled a distance of 205m. What angle?

[jmm5180]

Homework Statement

A 165N sled is pulled a distance of 205m. The task requires 5200J of work to overcome friction and is done by pulling a rope at what angle? Coefficient of friction is 0.25.

Homework Equations

W= Fdcos@ (@ for theta)
F= ma

The Attempt at a Solution

My free body diagram had Force applied in the y direction (Fay) and normal force along the positive y-axis and weight on the negative y axis. Force applied in the x direcrion (Fax) is on the positive x-axis and the force of friction is on the negative y axis.

I tried to solve for a variety of variables, but i can't get the right combination so two unknowns aren't in the same equation. I believe I need to find the force applied before I can get theta.

I solved that Ff = Facos@ (Force applied in the x direction)

For the y direction:
Fasin@ = -N + W
I solved for Fa then..
Fa= (-N+W)/sin@

I plugged that back into Ff= Facos@
Ff= cos@* (-N+W)/sin@

However, normal force is another unknown. I'm not sure where else to go from here.

Thanks in advance.

 

[TomHart]

force of friction is on the negative y axis.

I think you meant "force of friction is on the negative x axis", true?Where does the 5200 J and 205 meter distance and 0.25 coeff. of friction come into play . . . or not?