- #1
LDC1972
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Homework Statement
Find piston velocity and
Find angular velocity AB about A.
I apologise if the image is poor! If very bad I'll elaborate in writing the values...
Homework Equations
Draw a velocity vector diagram to solve the above.
Also use 2∏RPM / 60 to convert crank speed from 3000 rpm to 314.16 rad / s
And then Wr to get 31.416 metres per sec angular speed of point A
And for "angular velocity AB about A" used Wab = Vab / Length ab = 17.4 / 0.2 = 87 rad / s. (But book says answer should be 21.25??
The Attempt at a Solution
Attached below my 'sketch'. I did this to clarify as well:
This is a simple slider crank example from one of my own books; the book gives the answers but not the method.
The answers given by book are:
34 m/s piston velocity (and I get this right)
21.25rad/s for angular velocity of AB about A. (I get 87 rad/s?)
Please help, question and my space / velocity diagram below.
Basically I did this:
1/ Drew question schematic to scale
2/ Drew Vector Vao (90 degrees to AO)
3/ Drew Vector Vab (90 degrees to AB at piston)
4/ Convert crank rpm to rad/s and then calculate Voa ( Voa = crank rad/s x length 0.1m)
5/ Draw vectors using the angles calculated from above methods (Voa being 30 degrees on right hand side from horizontal)
(Vab being 65 degrees from left hand side horizontal.
6/ Once first vector drawn point A is know, so join next (Vab) to a, and finally measure ao (Vao) to find o, and then drew horizontally across to find b.
7/ Then do Wab = Vab / length ab = 17.4/0.2 = 87 rad/s
