Calculating Distance Given Work and Forces

[Natko]

Homework Statement

A farmhand does 972 J of work pulling an empty hay wagon along level ground with a force of 310 N [23 degrees below the horizontal]. A frictional force of 280 N opposes the motion. The distance the wagon travels is
a. 0.39 m
b. 1.7 m
c. 3.4 m
d. 32 m
e. 1.8 x 10² m

Homework Equations

W=FcosΘd
F_net=F₁+F₂

The Attempt at a Solution

W=Fd
d=W/F
d=972/(310cos23-280)
d=180 m

Apparently, the correct answer is c) 3.4 m, which works if you don't account friction, but I don't understand how that's correct.

 

[PhanthomJay]

Homework Statement

A farmhand does 972 J of work pulling an empty hay wagon along level ground with a force of 310 N [23 degrees below the horizontal]. A frictional force of 280 N opposes the motion. The distance the wagon travels is
a. 0.39 m
b. 1.7 m
c. 3.4 m
d. 32 m
e. 1.8 x 10² m

Homework Equations

W=FcosΘd
F_net=F₁+F₂

The Attempt at a Solution

W=Fd
d=W/F
d=972/(310cos23-280)
d=180 m

Apparently, the correct answer is c) 3.4 m, which works if you don't account friction, but I don't understand how that's correct.

You have divided the work done by the farmhand by the net force . If you are going to use the net force, you need to use the net work, not the work done by the farmhand.

 

[electricspit]

I was wrong