Block and strut (Equilibrium)

In summary, the system shown in the picture is in equilibrium with a steel block of mass 248 kg and a rigid aluminum strut of mass 47 kg. The angles between the left wire and the ground and between the strut and the ground are 32o and 49o respectively. Using the equation torque = rFsin(theta), the tension in the vertical wire holding the steel block is found to be 2432.88 N. However, there is an error in the calculation for the tension in the left angled wire, as the expression should use sin(49-32) instead of cos(49-32). Also, all masses should be multiplied by g to take into account their weights.
  • #1
Bryon
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0
https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/phys2111/fall/homework/Ch-12-Equilibrium/block-strut/block-strut-eq.gif [/URL]

Sorry, forgot to add the picture...

1. Homework Statement

The system shown to the right is in equilibrium. The steel block has a mass m1 = 248 kg and the uniform rigid aluminum strut has a mass m2 = 47 kg. The strut is hinged so that it can pivot freely about it's bottom end. The angle between the left wire and the ground is Θ = 32o and the angle between the strut and the ground is φ = 49o



Homework Equations



torque = rFsin(theta)

The Attempt at a Solution



a) What is the tension in the vertical wire that holds the steel block? 2432.88 N
b) What is the tension in the left angled wire?

torque(hinge) = 0 = m(block)Lcos(49) + 0.5(m(strut)Lcos(49) - T2Lcos(49-32)
I got T2 = 1827.197

That seems low for where the pivot is.
Any idea were I screwed up? Thanks!
 
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  • #2
We can't help you because we can't see "the system shown to the right."
 
  • #3
Sorry about that...forgot to add the pic.
 
  • #4
You need sin(49-32) in your expression, not cos(49-32). Think of it this way, if Θ = Φ, i.e. the cable is pulling in along the direction of the strut, the torque due to the tension should be zero. This is the case if you use the sine and not the cosine.

Also, be sure to multiply all masses by g to get the weights. Your expression omits g.
 

1. What is block and strut equilibrium?

Block and strut equilibrium, also known as block-and-tackle equilibrium, is a principle in physics that explains the balance of forces in a system where a block is supported by a series of struts.

2. How does block and strut equilibrium work?

In block and strut equilibrium, the forces acting on the block are balanced by the forces exerted by the struts. The struts are arranged in a way that distributes the weight of the block evenly, creating a stable system where the block remains in place.

3. What are the main components of a block and strut equilibrium system?

The main components of a block and strut equilibrium system are the block, which is the object being supported, and the struts, which are the supports or ropes that hold the block in place. Other components may include pulleys and weights.

4. What is the purpose of using block and strut equilibrium?

The purpose of using block and strut equilibrium is to distribute the weight of an object evenly and create a stable system. This can be useful in applications such as lifting heavy objects or creating mechanical advantage.

5. How is the mechanical advantage calculated in a block and strut equilibrium system?

The mechanical advantage in a block and strut equilibrium system is calculated by dividing the weight of the object being lifted by the force applied to the rope or strut. This ratio represents the amount of force amplification achieved by using the system.

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