Physics forces and waves

difference between longitudinal and transverse waves

longitudinal waves have vibrations parallel to the direction of energy transfer; transverse waves have vibrations perpendicular to the direction of energy transfer

amplitude

the maximum displacement of a wave from its rest position

wavefront

a line joining points on a wave that are in phase (e.g. same point in a cycle)

frequency

number of waves passing a point per second (measured in Hz)

wavelength

the distance between two corresponding points on consecutive waves (e.g. crest to crest)

period of a wave

the time taken for one complete wave to pass a point

wave speed

distance travelled by a wave per second (measured in m/s)

wave energy transfer

waves transfer energy and information without transferring matter

wave equation

wave speed = frequency × wavelength (v = f × λ)

frequency and time period relationship

frequency = 1 / time period (f = 1/T)

sound and electromagnetic waves

use the same relationships for speed, frequency, and wavelength

Doppler effect

the change in observed frequency and wavelength when a wave source is moving relative to an observer

reflection and refraction

all waves can be reflected and refracted when they meet a boundary

effects of forces

forces between bodies can change speed, shape or direction

types of forces

gravitational, electrostatic, magnetic, frictional, tension, normal contact etc.

vector and scalar quantities

vectors have both magnitude and direction; scalars have magnitude only

force as a vector

force is a vector quantity because it has both magnitude and direction

resultant force

the single force that has the same effect as all the individual forces acting together

friction

a force that opposes motion between two surfaces in contact

relationship between unbalanced force, mass and acceleration

force = mass × acceleration (F = m × a)

weight, mass and gravitational field strength

weight = mass × gravitational field strength (W = m × g)

stopping distance

total stopping distance = thinking distance + braking distance

factors affecting stopping distance

speed, mass, road condition and reaction time