- #1
limenuke
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Homework Statement
Given the above diagram and that the arm R swings at a constant angular velocity theta dot (dtheta/dt), we are to solve for the velocity of the pin and the acceleration of the pin.
Homework Equations
h= (theta dot)*r^2
dtheta/dt = v
v= (theta dot) * dr/dt
The Attempt at a Solution
I've been struggling with these questions since they seem the easiest to do in polar but our professor has been working more specifically in cartesian. Our textbook doesn't seem to like using polar either so at the moment, I'm having a lot of trouble coming up with applicable formulas.
For velocity, I tried the above forumla...
dr/dt = dr/dtheta * dtheta/dt (chain rule)
sub in dtheta/dt =h/r^2
sub in dr/dt = v
sub in dr/dtheta = -Rsin theta since the circular arc traces part of the curve r= R cos theta
v = (-Rsin theta) (h/r^2)
Since they're asking for velocity, the only thing I put down to indicate a direction was unit vector e sub t where e sub t is the tangential component of arc DE. I've no idea if this answer is acceptable.
For acceleration, I have no idea where to start.
I just can't seem to know where to start. It would be helpful if someone could provide formulas or point me in the right direction. I'm looking for advice, not answers (yet).
Thanks!