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AQA A-Level Physics > Definitions > Flashcards

Flashcards in Definitions Deck (100)
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1

Vector

A physical quantity with magnitude and direction

2

Scalar

A physical quantity with magnitude only

3

Moment

Force times perpendicular distance from the line of action of the force to the point

4

Principle of moments

For an object in equilibrium, the sum of the clockwise moments is equal to the sum of the anticlockwise moments about any point

5

Couple

A pair of equal and opposite forces acting on a body, but not along the same line

6

Velocity

Change of displacement per unit time

7

Acceleration

Change of velocity per unit time

8

Newton's 1st Law

An object will remain at rest or at a constant velocity unless acted on by an external resultant force

9

Newton's 2nd Law

The force is proportional to the rate of change of momentum

10

Newton's 3rd Law

For every action there is an equal and opposite reaction

11

Equilibrium

State of an object when at rest or moving at constant velocity

12

Density

Mass per unit volume of the substance

13

Stress

Force per unit area of cross section in a solid perpendicular to the cross section

14

Strain

Extension per unit length of a solid when deformed

15

Young's Modulus

Tensile stress/strain

16

Limit of Proportionality

The limit beyond which, when a wire or a spring is stretched, its extension is no longer proportional to the force that stretches it

17

Plastic deformation

Deformation of a solid beyond its elastic limit

18

Elastic limit

Point beyond which a wire is permanently stretched

19

Hooke's Law

The extension of a spring is directily proportional to the force applied to it, up to the limit of proportionality

20

Isotope

Atoms with the same number of protons but different numbers of neutrons

21

Conservation of energy

Energy cannot be created or destroyed, only converted from one form to another

22

Work done

Force times distance moved in the direction of the force

23

Ductile

Material that can be drwan into threads, it can be shaped or permanently deformed without fracture

24

Brittle

Material cannot be permanently stretched

25

Wave

Transfer energy from A to B via a medium of transfer, without transferring the medium

26

Standing wave

When two waves travel in opposing directions and they have the same wave speed, frequency and in general amplitude, they will superpose and form a standing wave

27

Monochromatic

Single wavelength

28

Coherent

No change in phase relationship

29

Collimated

Formed in a narrow beam

30

Diffraction

Spreading out or bending of waves as they pass through a gap or around an obstacle