What is the downward force on a drawbridge at different angles?

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SUMMARY

The discussion focuses on calculating the downward force exerted on a drawbridge at various angles of elevation. The drawbridge in question is 8 feet long, 4 feet wide, and weighs 100 pounds, hinged at one end. As the angle changes from 0 degrees to 90 degrees, the force on the free edge varies due to the principles of torque and gravitational force. At 0 degrees, the force is 0 pounds, at 30 degrees it is approximately 50 pounds, at 60 degrees it is about 86.6 pounds, and at 90 degrees, the force equals the full weight of 100 pounds.

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  • Ability to perform calculations involving angles and forces.
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Engineers, physics students, and anyone involved in structural design or mechanics will benefit from this discussion, particularly those interested in the dynamics of levers and forces in construction applications.

solarblast
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Let's say I have something like a drawbridge that is 8' long (and 4' wide, not that it matters) and weighs 100 pounds. Let's say it is hinged at one of the 4' edges, and is otherwise flat on the ground. Suppose I grab the unhinged end and pick it up. What will the downward force as I pull it up say at 0 degrees, 30 degrees, 60 degrees, and when it is vertical (90 degrees)?

This is a real problem, but the above is a simplified version to the structure I have. It's more like a steel plate that is covering a window, and eventually a winch at the top will open and close the window with the plate.
 
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What do you think the force on the free edge is? Say the bridge is flat on the ground.
 

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