What are the Internal Forces at Point C in a Distributed Load System?

In summary: So the tension in the cable is transmitted to the lever arm over the pulley.In summary, the author attempted to solve a homework question but was having trouble with one of the equations. The first equation appears to be correct, but the author is unsure why the T(0.6) was included in the equation. The second equation is the most straightforward and the author got it correct.
  • #1
Isaac Reed
5
0

Homework Statement


upload_2015-4-17_22-32-56.png

find internal normal, shear, and moment forces at point C, P=8kn

The Attempt at a Solution


for the most part I can solve this entire question but looking at the solution for it one of my equations is different and I cannot figure out why.
my equation for finding T(tension in cable)
ΣMa=0: 8(2.25)-T(.75/.96)=0
gives T=28.84kN

equation 2
ΣMa=0: -T(0.6)+8(2.25)=0 ←?
gives T=30.00kN
 
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  • #2
I don't see where your 1st equation comes from.

2nd equation looks right.
 
  • #3
but why exactly the T(0.6) in 2nd equation
 
  • #4
Isn't it the lever arm 0.5m+0.1m?
 
  • #5
how does all of the tension in the cable get transmitted to the lever arm over the pulley?
 
  • #6
Just as anything else. If the pulley is not rotating then the tension in the cable is constant for its entire length.
 
  • #7
Isaac Reed said:
how does all of the tension in the cable get transmitted to the lever arm over the pulley?
You didn't respond to paisiello2 comment in post 2, but it appears you tried to treat this as a truss at the joint where load P is applied by isolating the joint and assuming all the vert applied load is taken by the cable. But some of it is taken in shear by the lower member. Trust your equilibrium equations when determining support reactions from externally applied loads.
 
  • #8
Ahhhhhhh OK because the cable is only in the x direction after it goes over the pulley all of its y components are transferred to the beam. So if I finish my first equation I end up with.

ΣM=0: 8(2.25)-T(cos33.7)(2.25)+T(cos33.7)(1.5)=0
And I get T=30
 
  • #9
Not sure what you did there but if you draw a proper free body diagram you will see directly that the 2nd equation in your OP is the most straight forward.
 
  • #10
It is clearly the most straiforward. But how is the component of the tension at the end of the beam not included in equation?
 
  • #11
Draw a free body diagram. The rope is only cut at one location. The rest is internal.
 

FAQ: What are the Internal Forces at Point C in a Distributed Load System?

1. What is a distributed load in statics?

A distributed load in statics refers to a type of force that is spread out over a specific area or length, rather than being concentrated at a single point. It is commonly used to model the weight or pressure of objects that are distributed along a certain surface or structure.

2. How is a distributed load different from a point load?

A point load is a single force that is applied at a specific point, while a distributed load is spread out over an area or length. Point loads are usually easier to calculate and model, but distributed loads are more realistic and commonly encountered in real-world situations.

3. What are the units of measurement for a distributed load?

The units of measurement for a distributed load depend on the type of load and the units of measurement used for other quantities in the problem. For example, a distributed load due to weight may be measured in pounds per foot or kilograms per meter.

4. How do you calculate the total force of a distributed load?

To calculate the total force of a distributed load, you need to integrate the load function over the length or area where it is applied. This will give you the total force in Newtons or pounds. Alternatively, you can break the distributed load into smaller sections and use the formula for calculating the area or length of a shape to find the total force.

5. What are some common examples of distributed loads?

Some common examples of distributed loads include the weight of a person or object on a floor or bridge, the pressure of water or wind on a surface, and the weight of soil or other materials on a structure. Distributed loads are also commonly used in engineering and construction to model the weight of building materials such as steel beams and concrete slabs.

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