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Jan 13, 2008

2/142

for problem 2/142- you can solve for v and a in in polar coordinates basically by plug and chug- but to find the magnitude- do you have to convert to cartesian coordinates first?
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5 comments:

Carlos said...

Do you need to change deg/s to rad/s?

January 13, 2008 at 2:58 PM
David Rojas said...

yes, you should put the d-theta in rad/s. Also, don't forget to be careful when using your value for r.

January 13, 2008 at 3:14 PM
CMK said...

No need to convert to Cartesian to find magnitudes.

So long as your unit vectors are orthogonal (as e_r and e_theta are), the magnitude of a vector is equal to the square root of the sum of the squares of the components.

January 13, 2008 at 3:22 PM
Chris Cohoat said...

Would R simply be used as 500 mm in the problem? Or would it be something different depending on if we're dealing with velocity or acceleration?

January 13, 2008 at 10:08 PM
CMK said...

You are correct; R = 500 mm for both the velocity and acceleration equations.

David's caution above is a good one. He is saying that R is the TOTAL distance from O to B, not just the part of the arm that is extending.

January 13, 2008 at 10:14 PM

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