Chapter 10 : Static Equilibrium ; Elasticity & Fracture
Conditions for
Equilibrium
First Condition for Equilibrium
Second Condition for Equilibrium
Stability & Balance
If the forces on an object are such that they
tend to return it to its equilibrium position,
it is said to be in stable equilibrium.
If the forces tend to move it away from its equilibrium point, it is said to be in unstable equilibrium
An object is unstable if it is tipped,
so that its center of gravity is
outside the pivot point.
Elasticity
Stress
Strain
Tension
Compression
Shear
Hooke's Law
Shear Modulus, G
Bulk Modulus,B (Fluids)
Fracture
When stress too great,
the object will fracture
Horizontal Beam will be
under tensile & compressive
When designing a structure, it is a
good idea to keep anticipated stresses
less than1/3 to 1/10 of the ultimate strength
Trusses & Bridge
Basically, a truss is a framework of rods
or struts joined together at their ends by
pins or rivets, always arranged as triangles
On real bridge, the load will not in general,
be centered. The maximum load rating for
a bridge must take this into account
Arches & Domes
Larger bridges has suspension from
towers by closely spaced vertical wires
Stones & Bricks in a round arch
are mainly under compression,
which tends to strengthen the structure
Pointed arches require considerably
less horizontal force than a round arch
