How Do You Calculate Reaction Forces in Force Diagrams?

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SUMMARY

The discussion focuses on calculating reaction forces in force diagrams, specifically for a scenario involving a pivot and two reaction points on the ground. The established reaction forces are 498.1N upwards and 92.8N upwards, alongside a horizontal force of 104.2N. Key calculations involve using trigonometric functions, such as 600 sin 10 and 600 cos 10, to derive the forces acting on the system. The solution emphasizes the importance of summing moments about the hinge to accurately determine the vertical reaction forces.

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Deathfish
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1. 1. Homework Statement

Ok. I'm given a force diagram, and I have to figure out the reaction forces at the two points on the ground.

moments1.gif


answer key: (498.1N↑; 104.2N→, 92.8N↑)


Homework Equations



Ok. I only got so far as the x-reaction force at the pivot... 600 sin 10 = <- 104.2N


The Attempt at a Solution



Total y-reaction forces - 600 cos 10 = 590.88N

600 cos 10 = 590.88N
600 sin 10 = 104.2N

root 0.2^2 x 0.3^2 = 0.36m

104.19N x 0.3m = 31.257Nm
590.88N x 0.2m = 118.177 Nm

498.1N + 92.8N = 590.9N

i can't figure out how to get 498.1N and 92.8N at the two points respectively...
anyone can show how to achieve the answer? Thx
 
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Sum of moments about any point = 0. Try summing moments of all forces about the hinge to solve for the vertical reaction at the left support. Watch plus and minus signs (ccw and cw moments). Don't forget the moment from both the vertical and horizontal components of the appied force.
 

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