Statics Flashcards
Equation of moment
And units
Moment = Force x perpendicular distance
Units : Nm
The principle of moment
The sum of clockwise moments is equal to the sum of anti-clockwise moments about a given point
What is a couple?
Two PARALLEL forces of equal magnitude but in opposite directions
What is a scalar quantity?
A quantity with only magnitude
What is a vector quantity?
Quantities with magnitude AND direction
Types of stress
Tensile Compressive Torsion Shear Bending
What is the equation for stress?
Units?
Stress = Force/Area
Units: N/m^2 or Pa
What is the equation for strain?
Units?
Strain = deformation / original length
Units : NO UNITS
What is the equation for youngs modulus?
Units?
Youngs Modulus = Stress/ Strain
Units : N/ m^2 or Pa
What does Hooke’s Law state?
Stress is directly proportional to strain
What does a higher youngs modulus mean?
Substance is stronger
What is another name for the linear region?
Elastic region
What is the bulk modulus?
The bulk modulus gives the changes in volume of a substance as the pressure on it is changed
Bulk modulus equation and units
Bulk modulus = Pressure/ Volumetric Strain
Units : N/m^2 or Pa
When a plane is in flight, where would the tensile and compressive stress be located?
When the plane is stationary?
Tensile on the bottom, compressive on the top. - in flight
Tensile on top, compressive on the bottom. - stationary
Properties of a solid?
Toughness Hardness Ductility Brittleness Plasticity Elasticity Malleability
Properties of a liquid and gas
Vapor Volatile Flammable Flash point Toxicity Inert
What is toughness?
Ability to resist breakage when deforming or impact forces are applied to it
Hardness
The resistance a substance has to indentation or to any action tending to penetrate its surface
Malleability
Can be beaten, rolled or pressed into a shape without fracturing
Brittleness
Can break with little or no change of shape
Ductility
Can be stretched into new shape without breaking and can keep its new shape after the force is removed
Plasticity
The ability to be readily forced into a different shape permanently without fracture
Elasticity
The ability to return to its original shape after the distorting force is removed
Vapor
Ability for a gas to be liquified by an increase in pressure without a decrease in temperature
Volatile
A liquids ability to readily evaporate at normal temperature
Flammable
The ability to catch fire easily
Flash point
Flashpoint of a combustible liquid is the temperature it has to be before it will catch fire to a naked flame
Toxicity
How poisonous the substance is
Inert
Inability to chemically combine with another substance
Pressure (solids) equation
Units?
Pressure = Force/ Area
Units : Pa or N/m^2
What does the Archemides Principle state?
When an object is submerged in a liquid, the object displaces a volume of liquid equal to its volume and is supoorted by a force equal ti the weight of the liquid displaced
What is the normal force in a liquid called?
buoyant force
Volume displaced equation
Volume of object x % submerged
How much is submerged equation as a percentage
Density (block)/ density(water) x100
What methods can be used to add vectors?
Triangle and parallelogram methods
What is the meaning of the center of gravity?
The point which the weight of a body may be considered to act
What is the proportional limit?
Maximum stress and strain the material can withstand before deformation
What is Poisson’s ratio?
The ratio of the proportional decrease in a lateral measurement to the proportional increase in length in a sample of a material that is elastically stretched
