Trade Science Flashcards
All matter is composed of what?
Atoms
Define an Alloy
A mixture of a metal with another metal, or non metal
Define Mass
The measurement of the quantity of material in a body
Define Density
The mass of a body in a given volume
The point at which a material ruptures
Ultimate strength
Define tensile strength
The ability of a material to resist being pulled apart by external forces
Define compressive strength
The ability of a material to resist external forces pushing into or against the material
Define shear strength
The ability to resist forces that try to slide part of the object along itself (shearing a rivet)
Define fatigue strength
The ability to withstand repeatedly alternating stresses
Define elasticity
The ability of a material to return to its original dimensions after it has been acted on by a force
Define elastic limit (yield strength)
The max force that a solid can withstand without being permanently deformed
Define plasticity
The ability of a material to retain shape permanently after a force is removed
Define ductility
A materials ability to stretch and maintain the new shape (material being drawn through a die to create wire)
Define malleability
The ability of a material to be permanently deformed by compression forces
Define brittleness
Material breakage without noticeable plastic deformation. The absence of malleability. (Glass)
Define toughness
Ability of a material to withstand shock loads
Define hardness
A materials ability to resist force trying to penetrate it (separate the molecules)
Thermal conductivity determines:
The rate of heat flow through a material
Expansion coefficient for steel
For every 150•F change in temperature, each inch of length and diameter changes by 0.001” (one thou)
How much PSI=1 Atmosphere (ATM)?
1 ATM = 1 bar = 14.7 psi
Define heat
Energy in transit from a body at higher temperature to a body at a lower temperature
Newtons 1st law
A body at rest will stay in 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
Newtons 2nd law
The size of a net force (F) on an object is equal to the product of the mass (m) and the acceleration (a) of the object
F= m x a
Newtons 3rd law
For every action there is an equal and opposite reaction
General definition of work
Work is done whenever one kind of energy is converted to another type of energy
First class lever
Fulcrum between the resistant force and the effort (see-saw)
Second class lever
The resistance is between the fulcrum and the effort (wheel barrel)
3rd class lever
The effort is applied between the resistance and the fulcrum (engine hoist)
What is a vacuum
A container with lower pressure inside than the pressure outside (less than 14.7psia)
What is the most accurate way of measuring a vacuum?
A manometer
How do you convert PSIG to PSIA?
Add 14.7 to your PSIG reading
Can fluids be compressed?
No
What are the 3 ways to increase pressure in a sealed container?
1) increase the temperature
2) reduce the volume of the container
3) pack more gas into the container
What is Pascal’s Law?
Pressure applied to a confined static fluid transmits equally in all directions at right angles to the surface of its container
What is Bernoulli’s Principle?
When the velocity of a fluid increases the pressure decreases, and vice versa
What does the Compression Ratio compare?
The volume of gas in a vessel before and after compression
What is Boyle’s Law?
If the temperature is constant the volume of gas changes inversely to the pressure
(If pressure is doubled volume is half)
What is Gay-Lussac’s Law?
If the volume is constant, the pressure exerted by the gas is directly proportional to the absolute temperature
(If the absolute temperature doubles, so does the absolute pressure)
