JC1 Definitions List

A comprehensive set of vocabulary flashcards based on the provided physics lecture transcript covering measurements, mechanics, fields, oscillations, and waves.

Random error

Deviations of the measured value from the mean value, with varying signs and magnitudes

Systematic error

Deviations of the mean value from the true value, with the same sign and magnitude

Precision

A measure of how close the measured values are to each other

Accuracy

A measure of how close the measured values are to the true value of the physical quantity

Hooke’s Law

The extension of a spring is proportional to the applied force if the limit of proportionality is not exceeded

Upthrust

An upward force exerted on a body by a fluid when fully or partially submerged, due to the difference in fluid pressure at different heights

Principle of Moments

For a body in rotational equilibrium, the sum of all clockwise moments about any point is equal to the sum of all anticlockwise moments about the same point

Moment

The product of the force and the perpendicular distance from the line of action of the force to the pivot

Centre of gravity

The point where the weight on the body appears to act.

Displacement

The distance moved in a specified direction from a reference point

Speed

Rate of change of distance

Velocity

Rate of change of displacement

Acceleration

Rate of change of velocity

Linear momentum

The product of an object’s mass and velocity

Impulse

The product of a force acting on an object and the time which the force is exerted

Principle of conservation of momentum

The total momentum of a system remains constant when no net external force acts on the system

Elastic collision

A collision in which kinetic energy is conserved

Work done

The product of a force and the displacement in the direction of the force

Power

The rate of energy transfer

Angular velocity

Rate of change of angular displacement

Period

The time taken for a system to complete one cycle of motion

Newton's Law of Gravitation

Every point mass attracts every other point mass with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

Gravitational field strength

The gravitational force acting per unit mass at a point

Gravitational potential energy

The work done by an external force in bringing a test mass from infinity to that point

Gravitational potential

The work done per unit mass by an external force in bringing a test mass from infinity to a point

Simple harmonic motion

Motion in which the acceleration of an object is directly proportional to its displacement from its equilibrium position and is opposite in direction to its displacement

Free oscillation

Oscillations with constant amplitude and without energy loss or gain

Forced oscillation

An oscillation which is driven by an external force

Natural frequency

The frequency at which a body will vibrate when there are no driving or resistive forces acting on it

Wavelength

The distance moved by a wavefront during one period

Phase difference

How much one particle lags or leads another with respect to a cycle

Transverse wave

Particles oscillate perpendicular to the direction of energy transfer

Longitudinal wave

Particles oscillate parallel to the direction of energy transfer

Polarisation

Polarisation occurs when particles in a wave oscillate only in a single direction perpendicular to the direction of energy transfer of the wave

Principle of superposition

When two or more waves meet and overlap at a point, the resultant displacement at that point is the vector sum of the displacements that would be caused by each wave at that point

Diffraction

The bending or spreading out of waves when they travel through an opening or when they pass around an obstacle

Interference

The superposition of two or more coherent waves to produce regions of maxima and minima in space

Coherent waves

Waves with a constant phase difference

Rayleigh criterion

Two images are just resolved or distinguishable when the central maximum of one diffraction pattern coincides with the first minimum of the diffraction pattern of the other