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CHAPTER 11: STATIC EQUILIBRIUM - Coggle Diagram
CHAPTER 11: STATIC EQUILIBRIUM
The Conditions for Equilibrium
Equilibrium
is a state where force is acting on a te object but it has zero net force.
When the object is in equilibrium:
There is no torque around any axis(axis is arbitrary) when object in equilibrium.
Stability and Balance
Stable equilibrium
of an object is when the body is slightly displaced, it tends to return to its original position.
If thw forces tend to move it away from its equilibrium point,it is
Unstable Equilibrium.
An object in stable equilibrium may become unstable when tipped so that its centre of gravity is outside the pivot point . However, it will be stable once again.
When an object is balanced on a pivot the turning effect of the forces on one side of the pivot must balance the turning effect of the forces on the other side of the pivot.
Fracture
Fracture
is caused by a strain placed on an object such that it deforms beyond its elastic limit and breaks.
A horizontal beam will be under both tensile and compressive stress due to its own weight. So, it must be made of material that is strong under compreion and tension.
Trusses and Bridges
The
trusses
handle both tension and comprehension, with the diagonal ones in tension and the vertical ones in compression.
Truss Bridge
On real bridge the mass will not be centered.
Trusses are not suitable for larger bridges as its too heavy but we can use suspension bridge.
Arches and Domes
Arches
An arch is a pure compression form.
The stones and bricks in a round arc are mainly uner compression, which tends to strengthen the structure.
Point arches require less horizontal force than round arc.
Domes
A
dome
is similar to an arch, but spans a two-dimensional space.
Elasticity; Stress and Strain
Elasticity
ability of a deformed material body to return to its original shape and size when the forces causing the deformation are removed.
F = − k∆x
Hooke's Law: The change in length is proportional to the applied force.
Young's Modulus
measure of the ability of a material to withstand changes in length when under lengthwise tension or compression.
Young's modulus is equal to the longitudinal stress divided by the strain.
Stress
refers to the cause of the change (a force applied to a surface).
Force per unit area.
three types of stress:
Tension
stretches or pulls apart
Compression
shortens or crushes.
Shear
pushes part in opposire direction.
Strain
refer to change in some spatial dimension (length, angle, or volume) compared to its original value.
