Statics: Varying Force

  • Thread starter kehler
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  • #1
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Homework Statement


The jib crane is designed for a maximum capacity of 10kN, and its uniform I beam has a mass of 200kg.
a)Plot the magnitude R of the force on the pin A as a function of x through its operating range of x=0.2m to x=3.8m.
b)Determine the minimum value of R and the corresponding value of x
55gl86.jpg



The Attempt at a Solution


Totally stumped on this one. It'll be great if someone could point me in the right direction.
I didn't even think the force would vary with distance :S. Isn't it only the moment about the point that changes? How do I determine the change in force with distance?
 

Answers and Replies

  • #2
minger
Science Advisor
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The pin can only resist force in the y-direction due to the definition of a pin. This means that the resultant force at the pin will be the sum of all the forces in the y-direction. Obviously there is a constant -10kN due to the load, however the resultant force in the y-direction at the cable will be a function of the position.

Sum moments about the pin to get the vertical force in the cable. Then sum forces in the y-direction to get the force at the pin. Get three points to see if it's linear, if it is, then use the equation of a line.
 

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