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D4b34r5
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Homework Statement
A uniform diving board, of length 5.0 m and mass 53 kg, is supported at two points; one support is located 3.4 m from the end of the board and the second is at 4.6 m from the end (see the figure below). What are the forces acting on the board due to the two supports when a diver of mass 64 kg stands at the end of the board over the water? Assume that these forces are vertical. [Hint: In this problem, consider using two different torque equations about different rotation axes. This may help you determine the directions of the two forces.]
http://www.webassign.net/grr/chapter-08/fig-019.gif
Homework Equations
formula derived from image and question
The Attempt at a Solution
N1 is the left support and N2 is the left support.
(sigma)(Torque)= N1-N2-We-Wp then since the right support = o since it is the axis of rotation I solve accordingly for the left support force :
1.2N1=2.1We+4.6Wp
N1=(2.1(53)(9.8)+4.6(64)(9.8))/1.2
N1= 3313.21N or 3.313kN
I have tried taking the left support to be the axis of rotation and solved accordingly. I always end up with the answer that is correct for the other support(I have the answers from webassign but I never understood it the first time through and I am reviewing for a test) The answer ends up being 2.17 kN for the left support downwards and 3.31kN for the right support upwards. What am I doing wrong and why do I get the answer for the other support? Is it just coincidence? After I find the correct force for the one I know I can just take the summation of the forces and subtract to get the force acting on the other support.