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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 velocity of the
punch when t = 10 seconds if
θ
o
=
π
/12.
Set up velocity equation(s).
Let’s label some points on the
punch (A and B).
List the velocity equation for B.
What do I know in this equation?
Now back to the v
B
equation.
Problem Type:
Find:
Given:
Rigid Body Kinematics (doesn’t ask
about forces)
θ
=
θ
ο
sin
2π
t
Velocity of the punch and angular velocity of AB
First Step?
What do we know here?
Reflection:
This is more simple than the general case because
θ
was equal to
zero.
I we were working this entire problem from the beginning we would have
used the acceleration equations, realized we did not know
ϖ
AB
, and then used
the velocity equations to find it.
Long process!!!
Does the sign of the cross product make sense?
A
B
Really only r
B/A
.
How can we find v
A
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 Spring '05
 staff
 Acceleration, Angular Momentum, Velocity, velocity equation

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