Definitions Flashcards
What are derived units?
Units that are combinations of base units.
Derived units may be multiplied or divided but not added or subtracted.
Define homogeneous in the context of units.
When each term has the same base units, the equation is said to be homogeneous or ‘balanced’.
What is a scalar quantity?
A quantity that has magnitude/size.
What is a vector quantity?
A quantity that has magnitude/size and direction.
Define accuracy in measurements.
How close a reading is to its true value.
Define precision in measurements.
The spread of values/measurements; how closely values are clustered together.
What are random errors?
Errors that cause readings to scatter around the true value.
What is uncertainty in measurements?
The range of value within which a measurement is likely to be.
Define acceleration.
Rate of change of velocity.
What is displacement?
The straight line distance between start and finish points in that direction.
Differentiate between distance and displacement.
Distance is the actual path travelled; displacement is the straight line distance.
What is free fall?
The downward motion of an object under the influence of gravity with constant acceleration (g = 9.81 m/s²).
What is momentum?
The product of an object’s mass and velocity.
Define force.
DOUBLE CHECK
Rate of change of momentum
An interaction that changes the motion of an object.
What is impulse?
The product of force and the time during which the force is applied.
What type of collisions conserve total momentum?
Elastic collisions.
What does the law of conservation of momentum state?
Total momentum of an isolated system remains constant if no external forces act on it.
What is terminal velocity?
Constant speed of an object when the resultant force is zero due to large air resistance.
Define weight.
The force due to the gravitational field acting on an object.
What is the center of gravity?
The point on an object where the entire weight appears to act.
State Newton’s 1st Law.
A body remains at rest or constant velocity unless acted upon by a resultant external force.
State Newton’s 2nd Law.
The resultant force is proportional to the rate of change of momentum.
State Newton’s 3rd Law.
For every action, there is an equal and opposite reaction.
What is density?
Amount of mass per unit volume of a substance.
What does equilibrium mean in physics?
Net force and moment is zero; sum of clockwise moments equals sum of anticlockwise moments.
What is pressure?
The perpendicular/normal force applied per unit area.
What is torque?
Product of the force and the perpendicular distance to the pivot.
Define a couple in terms of torque.
Two equal and opposite forces whose line of action is different, creating a turning effect.
What is upthrust?
The resultant force on a submerged object due to pressure difference in a fluid.
Fill in the blank: The average/peak is not the true value; the readings are not centered around the true value, indicating _______.
Systematic Error.
Fill in the blank: The _______ of total momentum of an isolated system remains constant if no external forces act.
Conservation.
True or False: Total kinetic energy of a system is always conserved.
False.
What is Energy?
It is the stored ability to do work.
Energy can exist in various forms such as kinetic, potential, thermal, and more.
What is Work Done?
Product of a force & the distance moved in the direction of the force.
Work is measured in joules.
Define Gravitational Potential Energy.
Energy stored due to height/position of mass.
It is calculated using the formula PE = mgh, where m is mass, g is gravitational acceleration, and h is height.
What is Internal Energy?
It is the total of the microscopic kinetic & potential energies of particles of a material.
Internal energy is a key concept in thermodynamics.
Define Kinetic Energy.
Energy of an object due to its motion.
Kinetic energy is calculated using the formula KE = 1/2 mv², where m is mass and v is velocity.
What is Power?
Rate of work done.
Power is measured in watts.
What is Elastic Potential Energy?
Energy stored due to deformation or change in shape of an object.
Common examples include springs and rubber bands.
What is Efficiency?
The fraction of the useful power output obtained from the total power input.
Efficiency is often expressed as a percentage.
Define Brittle Materials.
Materials which do not undergo plastic deformation.
They break suddenly when the stress exceeds a certain limit.
What does Hooke’s Law state?
Force/load is proportional to extension/compression if proportionality limit is not exceeded.
It applies to elastic materials within their limits.
What is Ultimate Tensile Strength?
The maximum value of stress that an object can sustain before it breaks.
It is a critical factor in material selection.
Differentiate between Transverse and Longitudinal Waves.
Transverse waves have vibrations that are perpendicular to the direction of energy travel, while longitudinal waves have vibrations that are parallel.
Transverse waves include light waves, while sound waves are longitudinal.
What is Wavelength?
Distance moved by wave energy / wavefront during one cycle.
It is the minimum distance between two points with the same phase.
What is Frequency?
Number of oscillations per unit time (not per second).
Frequency is measured in hertz (Hz).
What is Amplitude?
Maximum displacement of a particle in the wave.
Amplitude is a measure of the energy of the wave.
What is the Doppler Effect?
Change in observed frequency when source moves relative to the observer.
It explains why a siren sounds different as it approaches and then moves away.
What is Young’s Modulus?
Ratio of stress to strain.
It measures the stiffness of a material.
What is a Progressive Wave?
The transfer or propagation of energy as a result of oscillations/vibrations.
Progressive waves carry energy, unlike standing waves.
What is the significance of Coherence in waves?
Two waves with a constant phase difference are said to be coherent.
Coherent waves are essential for interference patterns.
What is Strain?
Extension over original length (ratio).
Strain is a dimensionless quantity.
What is Stress?
It is the force per unit cross-section area required to stretch a material.
Stress is measured in pascals (Pa).
What happens during Necking?
Localized narrowing occurs at weak points when a sufficiently large force is applied.
Necking leads to the eventual breaking of the material.
What is Elastic Deformation?
Object returns to its original length when load is removed.
This behavior is characteristic of elastic materials.
What is Plastic Deformation?
Wire/body object does not return to its original shape/length when load is removed.
Plastic deformation occurs in ductile materials.
What is the significance of the area under a Force-Extension graph?
It is the work done in stretching a material.
The area represents the elastic potential energy stored by the material.
What is the Principle of Superposition?
When two waves of the same frequency/wavelength travel in opposite directions, the resultant displacement is the sum of the displacements of each wave.
Define Node in the context of stationary waves.
Position along the wave with no motion / zero amplitude.
Define Antinode in the context of stationary waves.
Position along the wave with maximum amplitude.
What is Constructive Interference?
When two waves meet, resulting in a displacement that is the sum of individual displacements, forming alternating maxima.
What is Destructive Interference?
When two waves meet, resulting in a displacement that is the difference of individual displacements, forming alternating minima.
What does Fringe Width/Separation refer to?
The separation between one bright fringe and the next bright fringe.
What are the properties of a Stationary Wave?
Does not transfer energy, amplitude varies along its length, and neighboring points vibrate in phase.
What is Diffraction?
The spreading of waves as they pass through gaps or around edges.
What is a Diffraction Grating?
An optical component with a pattern that disperses light into its constituent wavelengths.
What is Refraction?
The change in direction of a wave due to a change in speed.
What is the SI unit of Electric Current?
Ampere.
Define Charge in electrical terms.
It is the amount of electric charge that passes a point when a current of 1 Ampere flows for 1 second.
What is the SI unit of Charge?
Coulomb.
What does Ohm’s Law state?
The current through a metallic conductor is proportional to the potential difference across it, provided temperature remains constant.
What is Potential Difference?
Energy converted from electrical to other forms of energy per unit charge that passes through it.
What does Quantised mean in the context of charge?
Charge exists in discrete amounts, meaning charge on carriers is quantised.
What is Resistance?
The ratio of potential difference over the current for an electrical component.
Define Resistivity.
The resistance of a wire of a particular material for unit length.
What is a Thermistor?
A specific type of resistor that changes resistance with temperature.
What is the unit of voltage?
Volt.
What does E.m.f stand for?
Electromotive Force.
What is Internal Resistance?
Resistance within a power source that causes energy loss.
State Kirchhoff’s 1st Law.
The sum of currents into a junction equals the sum of currents out of the junction.
What is Kirchhoff’s 2nd Law?
The sum of e.m.f’s equals the sum of potential differences around a loop/circuit.
What does the Law of Conservation of Charge state?
Charge cannot be created or destroyed.
When does a battery deliver maximum power to a circuit?
When the load resistance of the circuit equals the internal resistance of the battery.
What is a Potentiometer?
An arrangement used to compare e.m.fs of two sources.
What is an Alpha particle?
Either helium nucleus OR particle containing two protons and two neutrons with mass 4u.
Define Baryon.
A type of hadron particle that is made up of three quarks (e.g. proton and neutron).
What is a Beta Particle?
Produced due to weak nuclear force/interaction. B-particles are fast moving electrons with a range of speeds up to 0.99c.
What is Gamma radiation?
y- radiation is part of the electromagnetic spectrum with wavelengths between 10^(-11) m and 10^(-13) m.
What is Radiation’s behavior in electric/magnetic fields?
Radiation can be deflected in electric/magnetic fields, and absorbed by thin paper or few cm of air.
True or False: Radiation is highly ionizing.
True.
What is a Hadron?
Class of heavy particles made up of quarks held together by strong nuclear force.
Define Isotopes.
Atoms (same element) which have the same proton number, but a different nucleon number.
What is a Meson?
A type of hadron particle that is made up of two quarks.
What is Nucleon number?
The number of protons together with the number of neutrons in the nucleus is called the nucleon number (or mass number) A.
What is Proton Number?
The number of protons in the nucleus of an atom (aka atomic number) Z.
What are the three sub-atomic particles that make up the simple model of the atom?
- Proton (positively charged)
- Neutron (uncharged but equal in mass to proton)
- Electron (negatively charged & much smaller in size & mass)
