Definitions of everything Flashcards
Includes most (not all) definitions in boxes.
random error vs systematic error
random error: when the measured readings are scattered about the true reading with no fixed pattern
systematic error: when the measured readings are consistently larger or consistently smaller than the true reading
accuracy vs precision
accuracy: how close the measured reading is to the true value
precision of a set of readings (diff from precision of instrument): how close the measured readings are to each other
Newton’s Third Law of Motion
when body A exerts a force on body B, body B exerts on body A a force of the same type that is equal in magnitude and opposite in direction.
Newton’s First Law of Motion
an object continues at rest or with constant velocity unless acted upon by a resultant force
The mass of a body
property of a body which resists change in motion
The weight of a body
force acting on the body due to a gravitational field
Newton’s Second Law of Motion
rate of change of momentum of a body is
[magnitude] directly proportional to the resultant force acting on it and
[direction] in the direction of the resultant force
The Principle of Conservation of Linear Momentum states that the
total linear momentum of an isolated system of interacting bodies before and after collision remains constant if no net external force acts on the system
The centre of gravity
the single point where the weight of a body may be considered to act
Hooke’s Law states that
the change in length of a material is directly proportional to the force applied on it when the limit of proportionality is not exceeded.
Upthrust is
equal in magnitude and opposite in direction to the weight of fluid displaced by submerged or floating object
Explain the origin of upthrust
pressure exerted by water increases with depth
pressure on bottom surface area of cylinder
greater than pressure on top surface area of cylinder
upwards force on bottom surface larger
than downwards force on top surface
net upwards force is upthrust
Principle of moments
For a body in rotational equilibrium, sum of clockwise moments about any point is equal to sum of anti-clockwise moments about the same point
a body is in rotational equilibrium when there is:
a body is in translational equilibrium when there is:
a body is in equilibrium when:
body is in translational equilibrium when there is
[magnitude] no resultant force
[direction] in any direction
a body is in rotational equilibrium
when there is
[magnitude] no resultant torque
[direction] about any point
a body is in equilibrium when
there is no resultant force in any direction and
there is no resultant torque about any point
work done by a force is
the product of the force and the displacement in the direction of the force
one radian is the
angle subtended at the centre of a circle by an arc length that is equal to the radius
angular velocity ω (NOT THE SAME AS ANGULAR FREQUENCY IN OSCILLATIONS) is
the rate of angular displacement swept out by radius
a gravitational field is
a region of space where a mass experiences a gravitational force
Newton’s law of gravitation states that the
[type of force] gravitational force of attraction between two point masses
[magnitude] is directly proportional to the product of the masses and
inversely proportional to the square of separation between the masses
Advantage of geostationary satellites? What are they used for?
Geostationary satellites allow transmission of signals between two regions at all times because the satellite will remain within “line-of-sight” of ground-based transmission and reception equipment.
They are useful for constant monitoring of weather especially in the equatorial region.
a geostationary satellite must:
have a period of 24 hour
be in circular orbit at a particular radius
orbit directly above Equator
move from west to east along same orbital axis as Earth’s rotation
gravitational field strength g at a point in the field is the
[type of force] gravitational force of attraction
[ratio] per unit mass
[specifics] by a small test mass
placed at that point
gravitational potential φ at a point in the field is the
[process] work done
[ratio] per unit mass
[specifics] in bringing a small test mass
from infinity to that point
an oscillation is
a complete to-and-fro motion between two limits
free oscillations are
oscillations with constant amplitude without energy loss or gain as there is no external force acting on the system
natural frequency is
the frequency at which a system vibratesin the absence of net external forces
simple harmonic motion is
a type of oscillatory motion
where the acceleration is:
[magnitude] directly proportional to displacement from the equilibrium position
and
[direction] directed opposite to displacement
damped oscillations are
oscillations where the amplitude decreases exponentially with time because of continuous loss of energy to surroundings due to negative work done against resistive forces so the total energy in the system decreases with time
critical damping
no oscillations occur, displacement is brought to zero in shortest possible time
forced oscillations are
oscillations where there is continuous input of energy by external periodic force that maintains the oscillation amplitude
resonance is
when the driving frequency of external periodic force equals to natural frequency of the system, and the resulting amplitude is maximum because there is maximum rate of transfer of energy from the external driver to the oscillating system
progressive waves
waves where energy is propagated from one place to another in the direction of wave travel without bulk movement of medium
phase φ
an angular measure (in either degrees or radians) of the fraction of a cycle completed by the oscillating mass
phase difference Δφ
measure of how much an oscillation is out of step with another oscillation at the same instant in time
Transverse Wave vs Longitudinal Wave
a transverse wave is one where the oscillations are normal to the direction of energy propagation
a longitudinal wave is one where the oscillations are parallel to the direction of energy propagation
the intensity of a wave is
rate of energy flow per unit area that is perpendicular to the direction of wave propagation
polarised wave
the oscillations are along one direction only, in a single plane that is normal to the direction of energy transfer of the wave
the Principle of Superposition states that
when two or more waves meet and overlap the resultant displacement is the vector sum of the displacement of each individual wave
interference is when
(principle of superposition) When two or more waves meet and overlap the resultant displacement is the vector sum of the displacement of each individual wave,
giving rise to a pattern of maximas and minimas
diffraction is the
spreading of a wave into geometric shadow when it passes through a slit or past an edge of an obstacle
What is the SAO framework?
check ur notes .-.
the Rayleigh Criterion states that
the limit for which 2 sources of light can be just distinguished is when the first minima of the diffraction pattern of one source coincides with the central maxima of the diffraction pattern of the other source
coherent waves
if two waves are coherent, there is constant phase difference between the waves
a stationary wave is formed when
two waves of the same type, same frequency, wavelength and speed, travelling in opposite directions towards each other, meet and overlap.
When asked to explain the formation of stationary waves
describe: • how 2 progressive waves of the same type are generated such that they are the same frequency, wavelength and speed • how the 2 waves are travelling in opposite directions towards each other • where the 2 waves meet and overlap
fundamental mode / fundamental frequency
the mode of oscillation that has the lowest possible frequency of the standing wave
torque of a couple is the
product of one of a pair forces and the perpendicular distance between the forces
Angular frequency ω (NOT THE SAME AS ANGULAR VELOCITY IN CIRCUILAR MOTION)
rate of change of phase of oscillating mass
Electric current is the
rate of flow of charge
electromotive force (e.m.f.) is
energy transformed from chemical to electrical per unit charge that is driven around a complete circuit
potential difference (p.d.) is
energy transformed from electrical to other forms per unit charge that is passing through the component
resistance is the
ratio of potential difference across component to current passing through it
a magnetic field is
a region of space in which a permanent magnet, a current-carrying conductor or a moving charge may experience a force
magnetic flux density B is
force per unit current per unit length of wire carrying a current is that normal to the magnetic field
Why magnetic force does no work
magnetic force always directed perpendicular to velocity of charged particle
no displacement in the direction of magnetic force so no work done
an electric field is
a region of space where a stationary charge
experiences an electric force
electric field strength E at a point in the field is
[type of force] electric force
[ratio] per unit positive charge
[specifics] on a small stationary test charge at that point
Coulomb’s Law states that the
[type of force ] electric force between two point charges is
[magnitude] directly proportional to product of the two charges and inversely proportional to the square of separation between the two charges
Explain why the electric field strength inside a thin conducting sphere is zero.
Electric charges in a conductor will move in an electric field.
Charges redistribute until there is zero field strength, so
no resultant force on charges so
no electric field
electric potential is the
work done per unit positive charge in moving a small test charge from infinity to that point
equipotential lines are
lines joining points in a field that have the same potential
Relationship between Electric Field Strength and Electric Potential
[magnitude] electric field strength E is numerically equal to the electric potential gradient at a point in the field
[direction] negative sign shows that the direction of field strength points towards direction of lower potential
When a soft iron core is inserted in a solenoid,
the core is magnetized
in the same direction as the magnetic flux density set up by the solenoid,
it adds to the magnetic flux density and strengthens the net magnetic field
