- #1
Dorothy Weglend
- 247
- 2
A clothes dryer is designed so that when the clothes reach an angle of 68 degrees to the horizontal, they fall. Rotation is constant, in a vertical circle. The radius of the dryer is 0.330 m.
I have solved this two different ways, and I get two different answers.
Method 1: I take the component of mg along Fc, so at any angle theta I have:
N = Fc + mg sin theta.
When N = 0, Fc = -mg sin 68, using Fc = mv^2/r,
v^2 = -rg sin 68
Method 2:
All I'm interested in is the y component, along which gravity acts. If N=0, then Ny=Nx=0. So I can just deal with vector along mg:
Ny = Fc sin theta + mg
Setting Ny = 0, and solving as above, I get:
v^2 = -rg/(sin 68)
These are obviously not equivalent (although they are close, numerically).
Can someone help me see which one is right, and why?
Thank you,
Dorothy
I have solved this two different ways, and I get two different answers.
Method 1: I take the component of mg along Fc, so at any angle theta I have:
N = Fc + mg sin theta.
When N = 0, Fc = -mg sin 68, using Fc = mv^2/r,
v^2 = -rg sin 68
Method 2:
All I'm interested in is the y component, along which gravity acts. If N=0, then Ny=Nx=0. So I can just deal with vector along mg:
Ny = Fc sin theta + mg
Setting Ny = 0, and solving as above, I get:
v^2 = -rg/(sin 68)
These are obviously not equivalent (although they are close, numerically).
Can someone help me see which one is right, and why?
Thank you,
Dorothy