Statics

Question 1

Statics definition

Answer 1

Branch of classical mechanics
Analysis of force acting on a physical system under equilibrium

Question 2

Newtons Laws of Motion
(3)

Answer 2

1. The body remains at rest, or in motion at a constant velocity, unless acted on by a force (inertia)
2. The force on a body is directly proportional to the body’s mass and acceleration (F = m x a); and
   3 For every action, there is always opposed an equal reaction (conservation of momentum)

Question 3

SI units used in statics
(3)

Answer 3

s / second / time
m / metre / length
kg / kilograms / mass

Question 4

Derived units from SI statics units (7)

Answer 4

Force / newton / [N], [kg x m/s²]
Pressure / pascal / [Pa] / [N/m²]
Velocity / [m/^s]
Acceleration / [m/s²]
Area / [m²]
Volume / [m³]
Density / [kg/m³]

Question 5

UNIT prefixes (8)

symbol/prefix/multiplication factor

Answer 5

T / tera / 10¹²
G / giga / 10⁹
M / mega / 10⁶
k / kilo / 10³
m / milli / 10⁻³
µ / micro / 10⁻⁶
n / nano / 10⁻⁹
p / pico / 10⁻¹²

Question 6

catenary - definition

Answer 6

Curve that an idealised hanging chain/cable assumes - under equal + pure tension across its length

Flipped, becomes an arch, under equal compression

Question 7

3 aspects of a force vector

Answer 7

Magnitude
Direction
Sense

Question 8

force vs. stress

Answer 8

the actual force exerted vs. the intensity of the force at material level

stress = force / Area
σ = F / A

Question 9

Bending moment

Answer 9

A bending force is called a moment

M = F x d
(force x distance)

Question 10

stress notation and units

Answer 10

denoted with sigma (σ) or tau (τ)
measured in pascals or N / m²

Question 11

Strain
definition, notation, units

Answer 11

ε = ∆L / L₀
Measure of the deformation of a material under stress
Denoted with an epsilon (ε)
No units (length/length), can be presented as a percentage (%) change of length

Question 12

Stress-strain relationship

Answer 12

Fundamentally related

Materials deform because of stress - HOWEVER deformation is not permanent if the stress remains below the yield stress

The stress-strain relationship for most materials is initially linear, becoming nonlinear as stress approaches the yield stress

Question 13

Modulus of elasticity

Answer 13

Rise/run of the linear (or elastic) portion of the stress-strain curve

Ε = σ/ε
MoE = stress/strain

Question 14

Modulus of Rupture

Answer 14

σmax
The ultimate strength of material, the maximum strength it can take before failure
MoR = highest pt of a stress-strain curve

Also known as:
Ultimate strength
Tensile strength
Bending strength
Compression strength
Modulus of Rupture

Question 15

Elastic vs. plastic deformation

Answer 15

Elastic deformation is recoverable (return to original shape after load is removed)

Plastic deformation is permanent (occurs after the material has been loaded beyond its yield point/strength)