Calculate Forces on Mr. Porter's Sign Outside Home

In summary, Mr. Porter has attached a 495N sign to a wall using a chain and rod at a 35 degree angle. The tension in the chain is 863N and the thrust force exerted by the rod is 706.9N. A diagram can help visualize the problem and the calculations involve determining the y-component of the weight and considering the angle of the rod. It is important to note that the rod is not placed horizontally, as it may initially seem.
  • #1
brandon1
34
0
I can't figure out how to do this one:

"Mr. Porter has attached a sign that has a weight of 495N to a wall outside his home. Determine: a) The magnitude of the tension in the chain; b) The thrust force exerted by the rod, if the angle is 35 degrees"

I'm not seeing how the answers are a) 863N and b)706.9N (my teacher gave us the answers)
 
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  • #2
Draw a diagram.
Weight is the y-component.
 
  • #3
Can you show us what you've done so far on getting the answers?

From the answers, the rod must be at 35 degrees to the wall, rather than the horizontal. It's really only two simple calculations, just draw a diagram of forces, all there is to it.
 
  • #4
What I'm not understanding is how the tension is 863N? If the signing is hanging straight down, shouldn't is be 495N [495sin(90)]?
 
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  • #5
It isn't hanging straight down.
 
  • #6
Where do you see that?
 
  • #7
There's the sign, a chain, a rod and 35 degrees. I'd say the rod's placed horizontally.
 
  • #8
This is all I can get.

Physics is not exactly my best subject :redface:
 

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  • #10
That makes a lot more sense
Thanks
 

FAQ: Calculate Forces on Mr. Porter's Sign Outside Home

How do I calculate the forces on Mr. Porter's sign?

To calculate the forces on Mr. Porter's sign, you will need to know the weight of the sign, the wind speed and direction, and the dimensions of the sign. You can use the formula F = A * Cd * ρ * v^2 to calculate the force, where A is the area of the sign, Cd is the drag coefficient, ρ is the air density, and v is the wind velocity. You can also use a force calculator or consult with a structural engineer for a more precise calculation.

What is the drag coefficient for a sign?

The drag coefficient for a sign can vary depending on the shape, size, and surface texture of the sign. It is a dimensionless quantity that represents the resistance of an object to motion through a fluid (such as air). The drag coefficient for a flat rectangular sign can range from 0.8 to 1.2.

How does wind speed affect the forces on the sign?

Wind speed plays a significant role in calculating the forces on Mr. Porter's sign. The higher the wind speed, the greater the force acting on the sign. This is because the force is proportional to the square of the wind velocity (v^2) in the formula F = A * Cd * ρ * v^2. Therefore, a small increase in wind speed can result in a significant increase in the force on the sign.

Is the sign in danger of falling over?

Without knowing the specific details of Mr. Porter's sign, it is difficult to determine if it is in danger of falling over. Factors such as the weight and design of the sign, wind speed and direction, and the strength of the supporting structure can all affect its stability. If you are concerned about the safety of the sign, it is best to consult with a structural engineer.

Can the forces on the sign be reduced?

Yes, the forces on Mr. Porter's sign can be reduced by making changes to the sign's design or location. For example, the sign's shape and surface texture can be modified to decrease the drag coefficient, or the sign can be placed in a sheltered area with less wind exposure. Additionally, reinforcing the sign's supporting structure can also help reduce the forces acting on it. Again, it is best to consult with a structural engineer for specific recommendations.

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