Trade Science Flashcards
What does a Class 3 Lever look like?
Fulcrum is at the end. Effort is in the center. Resistance is at the other end.
What is Newtons First Law?
A body at rest will stay at rest and a body in motion will remain in motion at the same speed and in the same direction unless acted on by some unbalanced force.
What is Newtons Second Law?
The size of a net force on an object is equal to the product of mass and acceleration of the object.
What is Newtons Third Law?
For every action there is an equal and opposite reaction.
What is a compound?
The product of two or more atoms that unite chemically. This creates a substance that has properties different from those of the combining elements.
What is a Atom?
A singular unit of an Element.
What is an Element?
Elements are materials only containing one type of Atom.
What are Cohesive Forces?
Like molecules having a strong attraction to one another.
What are Adhesive Forces?
The attraction of unlike molecules.
What is the Equation for Density?
Density = Mass/Volume
Define Tensile Strength
The ability of a material to resist being pulled apart by external forces.
Define Ductility
The ability of a material to stretch and maintain a new shape.
Define Malleability
The ability of a material to be permanently deformed by compressive forces.
Define Toughness
The ability of a material to withstand shock loads.
Define Hardness
A materials ability to resist a force that is trying to penetrate it.
What is the rule of thumb for expansion and contraction of steel?
For every 150F change in temp, each inch of diameter and length changes by 0.001 inches
Starting from Aluminum name all the Galvanic Series Metals.
Aluminum
Magnesium
Chromium Iron and Steel
Cast Iron
Cadmium
Nickel
Tin
Lead
Brass
Copper
Bronze
Copper-nickel
Silver
Platinum
Gold
Define Viscosity
A measure of a liquids resistance to flow.
The higher the viscosity of a fluid means what?
The greater it’s resistance to being poured.
What are the common units for gas under pressure?
- Pascal = Pa or Kilopascal = kPa
- pounds force per square inch = lbf/in^2 Or psi
What does psig stand for?
Pounds per square inch gauge
What does psia stand for?
Pounds per square inch absolute
What is ATM?
A unit used to describe the average pressure exerted by earths atmosphere at sea level.
What is 1 ATM equal to in kPa? What about bar? What about psi?
1 ATM = 101.35 kPa = 1 bar = 14.7 psi
What is the absolute temperature scale for Celsius?
Kelvin
What is the absolute temperature scale for Fahrenheit?
Rankine
What are the units used to measure heat?
Joules (J)
Kilojoules (kJ)
British Thermal Unit (Btu)
What is a Btu?
Heat needed to change 1lb of water by 1 Fahrenheit
What is 1 kilojoule equal to in Btu?
1 kJ = 0.948 Btu
What is 1 joule equal to in Newton meters?
1 J = 1 N•m
What are the three ways heat travels from one object to another?
Conduction, Convection, Radiation
What is sfpm?
Surface feet per minute. The amount of distance taken with a rotating surface. Used in imperial.
What is power?
The rate at which work is done. Work needs displacement.
What is the equation for work?
W = F•d
Force times displacement
What is 1 Watt equal to in joules/sec?
1W = 1 J/s
What is 1 hp = in Watts
1 hp = 746 W
What is 1 hp equal to in footpounds per second?
1 hp = 550 ft.lbf/s
How do you calculate the Mechanical Advantage of a belt drive?
MA = driver diameter /drive diameter
How to do you find Mechanical Advantage of a Chain or Gear Drive?
MA = # teeth on driven / # teeth on drive
Finish this: if the driven element is larger than the drive element, the rpm of the driven shaft is _____ than the rpm of the driver.
Less
Give the equation to find Mechanical Advantages of rpm of drive and driven elements.
Rpm drive x diameter drive = Rpm driven x diameter driven
What is the distance of two adjacent threads on a screw called?
Pitch
When a screw is turned on full rotation the screw travels a distance equivalent to _______.
The pitch
What is the equation for electrical Power?
P = Voltage x Current
P = V x I
What type of drill is often used in drilling concrete holes?
Carbide Twist Drills
