Physics term 3 wavelength🧬🌊

What is a wave?

A wave is a disturbance that transfers energy from one place to another without transferring matter overall.

What is the difference between a wave and the particles making up the medium?

The wave transfers energy, while the particles of the medium generally oscillate around their equilibrium positions rather than travelling with the wave.

What is a transverse wave?

A transverse wave is a wave in which the particles vibrate perpendicular (at 90°) to the direction in which the wave travels.

What is a longitudinal wave?

A longitudinal wave is a wave in which the particles vibrate parallel to the direction in which the wave travels.

What is the main difference between transverse and longitudinal waves?

In a transverse wave, particles vibrate perpendicular to the direction of travel. In a longitudinal wave, particles vibrate parallel to the direction of travel.

What are the highest and lowest points of a transverse wave called?

The highest point is the crest and the lowest point is the trough.

What is the equilibrium position of a wave?

It is the rest position of the particles when there is no disturbance.

What is amplitude?

Amplitude is the maximum displacement of a particle from its equilibrium position.

If the vertical distance from a crest to a trough is 12 cm, what is the amplitude?

Amplitude is half the crest

What happens to the amplitude if a wave becomes larger vertically?

The amplitude increases because the particles are being displaced further from their equilibrium position.

📏 WAVELENGTH

What is wavelength?

Wavelength is the distance between two consecutive points in phase, such as crest

What symbol represents wavelength?

λ (lambda).

What is the SI unit of wavelength?

Metres (m).

Can wavelength be measured from crest to trough?

Not as a complete wavelength. Crest

If the distance from one crest to the next crest is 4 m, what is the wavelength?

4 m.

If the distance from a crest to the following trough is 2 m, what is the wavelength?

Crest

🔄 FREQUENCY & PERIOD

What is frequency?

Frequency is the number of complete waves or cycles passing a fixed point per second.

What is the symbol and unit for frequency?

Symbol: f. Unit: hertz (Hz).

What does 1 Hz mean?

One complete cycle occurs every second.

What does 50 Hz mean?

50 complete cycles occur every second.

What is period?

Period is the time taken for one complete cycle.

What is the symbol and unit for period?

Symbol: T. Unit: seconds (s).

How are frequency and period related?

They are inversely proportional. When frequency increases, period decreases, and vice versa.

What is the formula for frequency?

f = 1 ÷ T

What is the formula for period?

T = 1 ÷ f

A wave has a frequency of 8 Hz. Calculate its period.

T = 1 ÷ f = 1 ÷ 8 = 0.125 s.

A wave has a period of 0.2 s. Calculate its frequency.

f = 1 ÷ T = 1 ÷ 0.2 = 5 Hz.

A wave has a frequency of 25 Hz. How many complete waves pass a point in 4 seconds?

Number of waves = frequency × time = 25 × 4 = 100 waves.

🌊 WAVE SPEED

What is wave speed?

Wave speed is the distance travelled by a wave per unit of time.

What is the formula for wave speed?

v = f × λ

What do the symbols in v = fλ represent?

v = wave speed in m/s, f = frequency in Hz, and λ = wavelength in m.

A wave has a frequency of 6 Hz and a wavelength of 3 m. Calculate its speed.

v = f × λ = 6 × 3 = 18 m/s.

A wave travels at 20 m/s and has a frequency of 5 Hz. Calculate its wavelength.

λ = v ÷ f = 20 ÷ 5 = 4 m.

A wave has a wavelength of 0.5 m and travels at 10 m/s. Calculate its frequency.

f = v ÷ λ = 10 ÷ 0.5 = 20 Hz.

A wave has a frequency of 10 Hz and a wavelength of 0.8 m. Calculate its speed.

v = fλ = 10 × 0.8 = 8 m/s.

🟠 MOTION — DISTANCE & DISPLACEMENT

What is distance?

Distance is the total length of the path travelled by an object.

Is distance a scalar or vector quantity?

Scalar, because it has magnitude but no direction.

What is displacement?

Displacement is the straight

Is displacement scalar or vector?

Vector, because it has both magnitude and direction.

Why can distance be greater than displacement?

Distance measures the entire path travelled, while displacement measures the straight

A student walks 8 m east and then 3 m west. What is the total distance?

8 + 3 = 11 m.

What is the student's displacement in the previous question?

8 m east − 3 m west = 5 m east.

A person walks 20 m north and then 20 m south. What is their distance?

20 + 20 = 40 m.

What is their displacement?

They finish where they started, so their displacement is 0 m.

🏃 SPEED

What is speed?

Speed is the distance travelled per unit of time.

Is speed a scalar or vector?

Scalar.

What is the formula for speed?

speed = distance ÷ time

What is the SI unit of speed?

m/s.

A car travels 240 m in 30 s. Calculate its speed.

speed = distance ÷ time = 240 ÷ 30 = 8 m/s.

A cyclist travels at 12 m/s for 25 seconds. How far do they travel?

distance = speed × time = 12 × 25 = 300 m.

A runner travels 150 m at a speed of 5 m/s. How long does the journey take?

time = distance ÷ speed = 150 ÷ 5 = 30 s.

🏎️ VELOCITY

What is velocity?

Velocity is the rate of change of displacement, including direction.

What is the formula for velocity?

velocity = displacement ÷ time

What is the SI unit of velocity?

m/s.

Why is velocity a vector?

Because velocity includes both magnitude and direction.

A car travels 100 m east in 20 seconds. What is its velocity?

velocity = displacement ÷ time = 100 ÷ 20 = 5 m/s east.

A student has a displacement of 60 m south over 15 s. Calculate their velocity.

velocity = 60 ÷ 15 = 4 m/s south.

Can an object have a speed of 10 m/s but a velocity of

10 m/s?

⚡ SPEED VS VELOCITY

What is the difference between distance and displacement?

Distance is the total path travelled and has no direction. Displacement is the straight

What is the difference between speed and velocity?

Speed uses distance and has no direction. Velocity uses displacement and includes direction.

Which are scalar quantities: distance, displacement, speed or velocity?

Distance and speed.

Which are vector quantities?

Displacement and velocity.

If an object returns to its starting position, what is its displacement?

0 m, regardless of how far it travelled.

If an object returns to its starting position, can its speed be zero?

Its average speed over the whole journey is not zero if it travelled a distance. Its displacement is zero, so its average velocity is zero.

🔥 CHALLENGE QUESTIONS

A runner travels 100 m east in 20 s and then 40 m west in 10 s. What is the total distance?

100 + 40 = 140 m.

What is the runner's displacement in the previous question?

100 − 40 = 60 m east.

What is the runner's average speed?

Total distance = 140 m. Total time = 20 + 10 = 30 s. Speed = 140 ÷ 30 = 4.67 m/s.

What is the runner's average velocity?

Displacement = 60 m east. Time = 30 s. Velocity = 60 ÷ 30 = 2 m/s east.

A wave has a frequency of 4 Hz and a wavelength of 2.5 m. How far does the wave travel in 6 seconds?

First calculate wave speed: v = fλ = 4 × 2.5 = 10 m/s. Then distance = speed × time = 10 × 6 = 60 m.

A wave travels at 15 m/s and has a wavelength of 3 m. Calculate its frequency and period.

f = v ÷ λ = 15 ÷ 3 = 5 Hz. Then T = 1 ÷ f = 1 ÷ 5 = 0.2 s.

🧠 LAST

MINUTE MEMORY CARDS

What does λ mean?

Wavelength.

What does f mean?

Frequency.

What does T mean?

Period.

What does v mean?

Velocity or wave speed, depending on the formula/question.

What is the wave

speed formula?

What is the frequency formula?

f = 1/T

What is the period formula?

T = 1/f

What is the speed formula?

speed = distance/time

What is the velocity formula?

velocity = displacement/time

Which two quantities need direction?

Displacement and velocity.

Which two quantities don't need direction?

Distance and speed.

What should every calculation include?

Formula → substitution → answer → unit. 💗