# Homework Help: Work (of worker, gravity, normal, total)

1. Oct 6, 2012

### Fizic

This is my first problem set involving work, so I want to make sure I'm doing it right. Thanks for checking.

1. The problem statement, all variables and given/known data
To push a 25.0 kg crate up a frictionless incline, angled at 25.0° to the horizontal, a worker exerts a force of magnitude 209 N parallel to the incline. As the create slides 1.50 m, how much work is done on the crate by (a) the worker's applied force, (b) the gravitational force on the crate, and (c) the normal force exerted by the incline on the create? (d) What is the total work done on the crate?

2. Relevant equations
W=Fdcos$\theta$
Fg=mg

3. The attempt at a solution

A) W=209*1.50*cos0
=313.5
=314 J

B) Wg=Fdcos$\theta$
=(9.8*2.50)*1.5*cos(115)
=-155.31
=-155. J

C) 0 J, since Fn is always perpendicular to movement along flat surface

D) Wnet=Wa+Wb+Wc...
=314-155
=159 J
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Oct 6, 2012

Looks good!