Physics Definitions Flashcards
Note what is meant by the ‘Elastic Limit’ of a spring
The maximum load the spring can experience and still return to its original length when the deforming force is removed
Define strain and state it’s expression and unit
Strain is the ratio of the change in length of a specimen to its original length
It’s expression is ε
It does not have a unit
Define Young’s Modulus and state it’s expression and unit
Young Modulus is a measure of the stiffness of a material, it is the ratio of stress to strain within the limit of proportionality
It’s expression is E
It’s unit is Nm^-2 or Pa
State Hooke’s Law and it’s equation
The extension of a spring, x, is directly proportional to the force applied, F, provided the limit of proportionality is not reached/exceeded
F=kx
Define the term “Limit of Proportionality”
The point beyond which Hooke’s Law is no longer true when stretching a material
Define Stress and state it’s expression and unit
The applied force per unit area of cross section
It’s expression is σ
It’s unit is Nm^-2 or Pa
State Charles Law
For a fixed mass of gas at a constant pressure, the volume is directly proportional to the temperature in Kelvin
V/T=k
State Boyles’ Law
For a fixed mass at constant temperature, the volume is inversely proportional to the applied pressure.
pV=k
State the Pressure Law
For a fixed mass of gas at constant volume, the pressure is directly proportional to the temperature in Kelvin
P/T=k
Define Ultimate Tensile Strength
The maximum stretching force per unit area without the material breaking
Define Mole
The mole is the amount of substance which contains as many particles as there are in 0.012kg of carbon 12
Define microscopic
Small scale
Define Macroscopic
Large scale
Define Isothermal
Constant temperature
What is STP
Standard temperature and pressure, taken as 0 degrees Celsius and 1x10^5 Pa
Define Specific Heat Capacity
The thermal energy required to raise the temperature of a body of mass 1kg by 1K
Define Centripetal
Centre seeking
Define Angular Velocity
The Rate of change of angular displacement
What happens to a system undergoing Simple Harmonic Motion?
In SMH the acceleration is directly proportional to the displacement and is always directed towards the fixed position
What is Damping
A resistive force which opposes motion and so causes the amplitude of a system to decrease
How does Resonance occur
Resonance occurs when a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies
What are Free Vibrations
Vibrations in which no energy is transferred to or from the system, thus amplitude remains fixed
What are Forced Vibrations
When a system is forced to oscillate at the frequency of an external oscillator (giving it energy) it undergoes forced vibrations
What is an Isotope?
Isotopes are atoms of an element with the normal number of protons and electrons, but different number of neutrons
Define Ionisation
Converting a substance into an ion or ions, typically by removing one or more electrons
Define Background Radiation
The ionising radiation present in the environment
Define Exponential Decay
Decay in which the amount falls by a fixed fraction per unit time
Define Activity
The number of disintegration’s per second in a sample, measured in Bq
What is a Decay Constant
The fraction of the total number of nuclei present to decay per unit time / second
What is a Half-Life
The time for the number of radioactive nuclei present to decay to half its original value
Define Nucleon
Any constituent that exists in the nucleus
Define Unified Atomic Mass (u)
1/12 of the mass of one atom of carbon 12, u = 1.66 x 10^-27kg
What is an Electron Volt (eV)
A unit of energy equal to the work done on an electron in accelerating it through a potential difference of 1 volt, 1eV = 1.6 x 10^-19 J
Define Binding Energy
The energy required to split up a nucleus into its constituent nucleons
What is Binding Energy per Nucleon
The average energy required to completely remove a single Nucleon from its nucleus
Define Mass Defect
The difference between the mass of the separated nucleus and the combined mass of the nucleus
Define Nuclear Fission
The splitting of a heavy / large nucleus into lighter nuclei with the release of energy
Nuclear Fusion
The joining of 2 light nuclei to form 1 heavier more stable nucleus which releases energy
What conditions are required for Fusion?
The nuclei must be confined within a finite volume at a sufficient temperature to increase the chances of collision with sufficient energy to overcome the electrostatic repulsion
