How Do You Calculate Reaction Forces in Force Diagrams?

AI Thread Summary
To calculate reaction forces in force diagrams, start by analyzing the forces acting on the system, including both vertical and horizontal components. The total vertical reaction forces can be determined using the equation 600 cos 10, resulting in approximately 590.88N. For horizontal forces, the calculation involves 600 sin 10, yielding about 104.2N. Summing moments about a pivot point helps isolate the vertical reactions at the supports, ensuring to account for all forces and their respective distances. Properly applying these principles will lead to the correct values of 498.1N and 92.8N for the reaction forces at the two points on the ground.
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
 
Physics news on Phys.org
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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