Problem 5/57 Page 358, Engineering Mechanics - Dynamics, Meriam and Kraige, 4th Edition
Given: A rod of length L with a known velocity at the left end and a known speed at the right end.
Find: The angular velocity of the rod.
L = 2 ft
vA = vA at an angle of q (ccw) with
the link (left end)
vA = 10 ft/s
q = 30 degrees
vB = vB at an angle of b (cw) with
the link (right end)
vB = 12 ft/s
The velocity two point formula can be used to relate the velocities
of the two ends of the rod. Letting +X run along the rod from the
left end toward the right end, and positive Y be perpendicular to the rod
so that ccw rotation is positive:
vB = vA + w X r
vB ( cos b i - sin b
j ) = vA ( cos q i + sin
q j ) + w
k X L i
vB ( cos b i - sin b
j ) = vA ( cos q i + sin
q j ) + w
L j
Equating components:
vB cos b = vA
cos q
-vB sin b = vA sin q
+ w L
Solving the first equation for the angle b
and then solving the second equation for the angular speed:
cos b = vA cos q
/ vB b
= 43.81 degrees
w = -(1/L) ( vA sin q
+ vB sin b ) = -6.65 rad/s