EX18.1-hole punch

EX18.1-hole punch - 5/130 Given: The punch is operated by a...

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5/130 Given: The punch is operated by a simple harmonic motion of the pivoted section. The motion is measured to be θ = θ o sin 2 π t. Find the acceleration of the punch when t = 10 seconds if θ o = π /12. Set up acceleration equation(s). Let’s label some points on the punch (A and B). List the acceleration equation for B. What do I know in this equation? Now back to the a B equation. Problem Type: Find: Given: Rigid Body Kinematics (doesn’t ask about forces) θ = θ ο sin t Acceleration of the punch First Step? What do we know here? Reflection: This is more simple than the general case because θ was equal to zero. We could have found the θ , ϖ , and α as a function of time and plotted out the accelerations as a function of time. If we knew the mass of the punch, we could also determine the forces on the pin at B. Does the sign of the cross product make sense? A B ( 29 A B AB A B AB AB A B r r a a / / 2 2 2 2 2 2 2 × + × × + = α ϖ Really only r B/A . We will talk about how to find ϖ AB next time – for now we are going to assume it is given as 2.3 rad/sec clockwise.
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This note was uploaded on 01/22/2011 for the course ME 212 taught by Professor Staff during the Spring '05 term at Cal Poly.

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