Sunday, October 16, 2011

UT HW6 #12 and 13

I am really stumped on these. Can anybody help me out?

3 comments:

Dr. Winters said...

#12 asks for the work done pulling a skier up a hill. W=Frcosθ

F is the force needed to pull the skier up the hill. This part is a force problem. Draw a force diagram. Make a chart of force parallel to the incline, perpendicular to the incline and "?" (idk). Sum the forces parallel to the incline (hint: the skier's velocity is constant) to find the force needed to pull the skier. That's F.

The problem gives you the distance up the incline. That's r.

The angle θ is the angle between the force (pulling up the incline) and the displacement (up the incline). NOT necessarily the angle they give you.

Hope that helps. Good luck.

B Walsh said...

I am also still confused on 13. I got an answer for 12 but don't know what 13 is asking for or what it's talking about.

B Walsh said...

Actually, I did the wrong division to find the time. Thank you Doctor.