Physics Definitions Flashcards
What is N1L?
an object at rest will remain at rest and an object in motion will remain in motion in the absence of an external resultant force
What is N2L?
The rate of change of momentum is directly proportional to the resultant force acting on it and is in the direction of the resultant force
What is N3L?
when body A exerts a force on body B, body B exerts the same type of force of same magnitude and opposite direction on body A
What is Principle of Conservation of Linear Momentum (PCOLM)?
Total momentum of a system remains constant provided no external resultant force acts on the system
What is principle of moments?
If a body is in equilibrium, the sum of all the clockwise moments about any axis is equal to the sum of all the anti-clockwise moments along the same axis
What is translational equilibrium?
No net resultant force acting on the body
What is rotational equilibrium?
No resultant torque acting on any point
What is archimedes’ principle?
When an object is totally or partially immersed in a fluid, the upward force acting on it is equal to the weight of the fluid displaced
What is the principle of floatation?
If an object is floating in equilibrium, upthrust is equal to the weight of the object
What is the principle of conservation of energy?
Energy can neither be created nor destroyed and can only be transferred from one form to another and from one body to another.
What is the work-energy theorem?
the net work done by external forces acting on a particle is equal to the change in kinetic energy of the particle
What is an ideal gas?
a hypothetical gas that obeys the equation of state of an ideal gas perfectly at all pressure, volumes and temperature
What are some assumptions of an ideal gas?
- Rapid and random motion
- No IMF (IMPORTANT PLS)
- Collision between molecules is perfectly elastic
What is internal energy ?
The sum of the random distribution of kinetic and potential energies associated with the molecules of a system.
!! different from internal energy of an ideal gas !!
What is the internal energy of an ideal gas?
The internal energy of an ideal gas is the sum of the kinetic energies of all its particles. The intermolecular forces of attraction between the particles are negligible.
What is iso-volumetric process?
changes takes place without a change in volume
What is isobaric process?
changes takes place without a change in pressure
What is an adiabatic process?
changes takes place without a change in temperature / no heat transfer
What is Newton’s Law of Gravitation?
The force of attraction between any 2 point masses is directly proportional to the product of their masses and is inversely proportional to the square of their separation
What is Kepler’s 3rd Law?
The square of the orbital period of a planet is directly proportional to the cube of the average distance from the sun. T^2 = R^3
What is the characteristic of Binary Stars?
Have the same angular velocity and in turn, the same period
Which direction do geostationary satellites orbit from?
West to East, together with the orbit of the earth
What is the definition of gravitational field strength?
The amount of gravitational force per unit mass acting on a small mass placed at that point.
What is gravitational potential?
work done per unit mass by an external agent to bring a mass from infinity to that point
What is the relationship between Gravitational Potential Energy and Gravitational Force?
Gravitational Force is the gradient of Gravitational Potential Energy (dGPE/dr)
What is the relationship between Gravitational Potential and Gravitational Field?
gravitational field is the gradient of gravitational potential (dGP/dr)
What is the relationship between gravitational potential and gravitational potential energy?
The change in gravitational potential energy is equal to the mass multiplied by the change in gravitational potential
What is escape velocity?
the minimum velocity a body must have at earths surface to escape from the influence of earths gravitational field
What is Simple Harmonic Motion?
Motion of a body whose acceleration is directly proportional to its displacement and is always directed to its equilibrium position
What is free oscillation?
A system which oscillates at its own natural frequency without external influences other than the initial impulse
What is the natural frequency of vibration?
The frequency at which an object will vibrate when its allowed to do so freely
What is the definition of phase?
defined as the angle in degrees or radians which gives a measure of the fraction of a cycle that has been completed
What is a phrase difference?
Measure of how much one wave is out of step with another
What is a damped oscillation?
Oscillation in which amplitude diminishes with time as a results of dissipative forces that reduce the total energy of the oscillations
What is a forced oscillation?
A system which is forced to oscillate at a frequency other than its natural frequency by a periodic external force
What is a forced frequency of vibration?
frequency at which an object is made to vibrate by imposing a periodic force on it
What is resonance?
A phenomenon when the frequency of an object made to vibrate is equal to its natural frequency of vibration
What is an example of useful resonance?
playing of musical instrument
What is an example of bad resonance?
mechanical resonance, which is the tendency of a mechanical system to respond at greater amplitude when the frequency of oscillations matches the systems natural frequency of vibration (e.g the bridge shaking violently when an army marches across it)
What is a progressive wave?
A wave which energy is transported from one end to the other but the particles within the wave are not transported along the wave.
What is a wavelength?
The shortest distance between 2 points on a progressive wave which are vibrating in phase.
What is a transverse waves + some examples?
Plane of oscillation is normal to the direction of transfer of energy of the wave
some examples are light waves
What is a longitudinal wave and some examples?
Wave which displacement of particles are along the direction of transfer of energy of the wave
some examples are sound waves
How to check is 2 points are in phase in a progressive wave?
check that they have the same velocity at the same displacement from the equilibrium position
What is the intensity of a wave?
( I = P/A) It is the wave energy incident per unit time per unit area normal to the wave / OR / power incident per unit area
What equipment can be used to measure the frequency of a wave?
Cathode Ray Oscilloscope and a microphone.
to set up, put a microphone at a set distance away from the sound source
another set up (frequency over displacement): put multiple microphones at a changing distance from the sound source
What is the definition of polarisation?
The confinement of oscillations in only one plane. The plane of oscillations is parallel to direction of energy transfer.
What is Malus’ Law?
the intensity of a plane polarised light after passing through a polarised is directly proportional to the square of the cosine of the angle through which the polarised is rotated from that gives max intensity.
