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Physics Facts Flash Cards
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- 1Thermal EquilibriumWhen the quantity of thermal energy is the same in two bodies.
- 2Zeroth Law of ThermodynamicsThe 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.
- 3Latent heatEnergy which is either absorbed or given out by a substance during a change in state without a temperature change.
- 4KelvinAn absolute temperature scale where 0K is equal to -273°C or absolute zero.
- 5Temperature DifferenceThe difference between two temperatures, can be described as ΔT = T₂ - T₁. Temperature difference is the same in °C and K.
- 6Specific Heat CapacityThe heat energy required to increase the temperature of 1kg of a substance by 1K
- 7Specific Latent HeatThe heat energy required to change the physical state of 1kg of a substance with no change in temperature.
- 8Work Done in Closed Loop SystemsIn 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
- 9The Second Law of ThermodynamicsThe 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.
- 10Adiabatic ProcessesProcesses 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.
- 11Isothermal ProcessA 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.
- 12Wasted EnergyEnergy which cannot be converted into 'useful' work, i.e. energy which escapes into the surroundings instead of going through the system.
- 13Co-efficient of PerformanceThe inverse of thermal efficiency, and therefore values bigger than 1 where Q is the 'useful' energy and work is the energy lost.
- 14Hooke's LawHooke'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.
- 15Young's ModulusThe Young's modulus, E, of an object is the total stress on the object divided by the strain on the object.
- 16Elastic LimitThe 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.
- 17Elastic HysteresisWhen 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.
- 18Plastic DeformationWhen the elastic limit of a material has been surpassed, it permanently deforms when the stress has been removed.
- 19DuctilityThe ability to be shaped by plastic flow when under tension. It is dependant on the temperature.
- 20MalleabilityA material is malleable if it is easily shaped by plastic flow when under compression.
- 21Ultimate Tensile StrengthThe Ultimate Tensile Strength (UTS) is the highest stress a material can take before it breaks.
- 22Brittle FailureWhen a brittle material cracks and shatters due to the load surpassing the UTS.
- 23CreepSlow plastic deformation which increases with temperature and can lead to failure if components don't fit.
- 24FatigueWhen a material fails due to repeated loading and unloading leading to a failure at a value lower than the UTS.
- 25Laminar FlowFlow 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.
- 26Turbulent FlowFlow which occurs at a higher rate and offers more resistance to the flow through rotational flow.
- 27ViscosityThe resistance which a fluid offers against the rate of flow.
- 28Newtonian FluidsFluids where the viscosity is (linearly) proportional to the local strain rate.
- 29Non-Newtonian FluidsFluids where the viscosity is not linearly proportional to the local strain rate and is affected by other properties.
- 30Pseudoplastic FluidsFluids where the viscosity decreases when the stress increases. (E.g. paint)
- 31Dilatant FluidsFluids which increase in viscosity when the stress is increased. (E.g. cornstarch)
- 32Thixotropic FluidsFluids where the viscosity gradually decreases when continual stress is applied. (E.g. honey)
- 33Rheopectic FluidsFluids where the viscosity gradually increases when continuous stress is applied. (E.g. cream)
- 34Bingham PlasticsFluids which behave like solids when under a low shear stress but behave like a liquid when above a stress yield.
- 35Mass flow continuityOnce 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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- Facts for physics without information relating to the diagrams.
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- Jack Glenwright
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