Physics Facts Flash Cards

Question	Answer
Thermal Equilibrium	When the quantity of thermal energy is the same in two bodies.
Zeroth Law of Thermodynamics	The law states that there is a physical quantity called temperature where two bodies at the same temperature will be in thermal equilibrium with one another.
Latent heat	Energy which is either absorbed or given out by a substance during a change in state without a temperature change.
Kelvin	An absolute temperature scale where 0K is equal to -273°C or absolute zero.
Temperature Difference	The difference between two temperatures, can be described as ΔT = T₂ - T₁. Temperature difference is the same in °C and K.
Specific Heat Capacity	The heat energy required to increase the temperature of 1kg of a substance by 1K
Specific Latent Heat	The heat energy required to change the physical state of 1kg of a substance with no change in temperature.
Work Done in Closed Loop Systems	In a closed loop system, the energy in (Qin) subtracted from the energy out (Qout) is equal to the change in internal energy (ΔU) and the work done (W). This can be expressed as: Qin - Qout = ΔU + W
The Second Law of Thermodynamics	The law states that it is impossible for heat energy to be completely changed into work or, heat will not flow from a cold body to a hot body without work being inputted into the system.
Adiabatic Processes	Processes which are thermally isolated, therefore Q=0 hence -W = ΔU. This would mean no energy can be wasted. It isn't possible to have a completely adiabatic process.
Isothermal Process	A process where two bodies are at thermal equilibrium and therefore heat can flow back and forth making the process reversible. They result in no net heat transfer between the two bodies.
Wasted Energy	Energy which cannot be converted into 'useful' work, i.e. energy which escapes into the surroundings instead of going through the system.
Co-efficient of Performance	The inverse of thermal efficiency, and therefore values bigger than 1 where Q is the 'useful' energy and work is the energy lost.
Hooke's Law	Hooke's law states that force is proportional to extension. This can be expressed as F=kΔx where F is force, k is the spring constant and Δx is the extension or change in length.
Young's Modulus	The Young's modulus, E, of an object is the total stress on the object divided by the strain on the object.
Elastic Limit	The elastic limit is the highest level of stress which can be applied to an object after which it can return to its original length. After this point it remains permanently extended.
Elastic Hysteresis	When a material doesn't follow Hooke's Law. Internal friction causes work to be lost as heat so the loading and unloading extensions are not the same.
Plastic Deformation	When the elastic limit of a material has been surpassed, it permanently deforms when the stress has been removed.
Ductility	The ability to be shaped by plastic flow when under tension. It is dependant on the temperature.
Malleability	A material is malleable if it is easily shaped by plastic flow when under compression.
Ultimate Tensile Strength	The Ultimate Tensile Strength (UTS) is the highest stress a material can take before it breaks.
Brittle Failure	When a brittle material cracks and shatters due to the load surpassing the UTS.
Creep	Slow plastic deformation which increases with temperature and can lead to failure if components don't fit.
Fatigue	When a material fails due to repeated loading and unloading leading to a failure at a value lower than the UTS.
Laminar Flow	Flow in a fluid where the fluid in contact with the surface has virtually the same velocity as the fluid in contact with the solid surface.
Turbulent Flow	Flow which occurs at a higher rate and offers more resistance to the flow through rotational flow.
Viscosity	The resistance which a fluid offers against the rate of flow.
Newtonian Fluids	Fluids where the viscosity is (linearly) proportional to the local strain rate.
Non-Newtonian Fluids	Fluids where the viscosity is not linearly proportional to the local strain rate and is affected by other properties.
Pseudoplastic Fluids	Fluids where the viscosity decreases when the stress increases. (E.g. paint)
Dilatant Fluids	Fluids which increase in viscosity when the stress is increased. (E.g. cornstarch)
Thixotropic Fluids	Fluids where the viscosity gradually decreases when continual stress is applied. (E.g. honey)
Rheopectic Fluids	Fluids where the viscosity gradually increases when continuous stress is applied. (E.g. cream)
Bingham Plastics	Fluids which behave like solids when under a low shear stress but behave like a liquid when above a stress yield.
Mass flow continuity	Once a steady state flow has been reached in a system of pipes, then the flow rate must be the same when entering and leaving the system.

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	Created by Jack Glenwright almost 6 years ago