🟡 In the picture · Level 1 · The Table

Each hit makes a wave

Every time the disc strikes a wall, a ring spreads out from that spot — exactly like a stone dropped in a pond. That expanding ring is a tiny wave: a disturbance carrying energy outward, while the surface it travels on only bobs in place.

A ring · per hitCarries energy, not matterSpeed · v = f λ7 question formats · layered hints

See it live

A ring per hit — each wall strike spawns a spreading ripple
Fading out — rings weaken as their energy spreads around a bigger circle

Watch the rings bloom from each contact point and fade as they grow. Every strike sends a little wave outward, just like a stone dropped in a pond — a disturbance carrying energy away while the surface only bobs. (This is an in-the-picture flourish, a visual echo of the impact, not the disc's own motion.)

What's going on

What it is

A wave is a disturbance that travels outward, carrying energy from one place to another without carrying the material itself along. Drop a stone in a pond and a ring of ripples spreads out; the water bobs up and down in place while the ring travels. In Kinetica, each wall strike spawns just such a ring — a little wave radiating from the point of impact.

How the principle works

A wave begins with a disturbance — the impact — that pushes the medium, which pushes its neighbour, and so on, passing the disturbance along while the medium stays put on average. A wave has a wavelength (the distance between crests), a frequency (how many pass each second), an amplitude (its strength), and a speed linking them: v = f λ. Ripples spread as expanding circles because the disturbance travels outward equally in every direction.

How it works in Kinetica

Each time the disc hits a wall, the game draws a ring expanding from the contact point — a wave spawned by the impact. The rings fade as they spread, the way real ripples weaken with distance because their fixed energy is shared around an ever-larger circle. It is an in-the-picture flourish, a visual echo of the physics of impact layered onto the motion, not part of how the disc moves.

Edge cases
  • The medium bobs in place → only the wave, and the energy it carries, travels outward.
  • Ripples weaken with distance → their fixed energy spreads around a bigger and bigger circle.
  • Bigger impacts → stronger, higher-amplitude ripples.
  • Wave speed → links frequency and wavelength: v = f λ.
Three points & measures
  • A wave — a travelling disturbance carrying energy, not matter.
  • Wavelength λ and frequency f — set by the source; v = f λ.
  • Amplitude — the wave's strength, which fades as it spreads.

The ripple laboratory

Waves come alive when you watch rings march outward at a steady speed — and see the crests bunch closer as you tap faster.

💧 Ripple emitter

A source sends out rings at a steady speed. Raise the frequency and the rings come more often, so the gap between them — the wavelength — shrinks, keeping v = f λ.
Frequency
0
Wavelength
0

The rings always travel at the same speed; tapping faster just packs more crests into the same distance, so the wavelength falls.

🤔 Guess before you reveal

Ripples spread out across a still pond toward the bank. Does the water itself travel all the way to the edge?

🧪 Wave-speed calculator — v = f λ

A wave's speed is its frequency times its wavelength. Enter both to find the speed. Try f = 2 Hz and λ = 0.5 m, then keep the speed and raise the frequency.

In the real world

Ripples on a pond

Toss a pebble in and rings spread outward, but a floating leaf only bobs up and down and stays put. That is the signature of a wave: the energy travels across the water while the water itself goes nowhere.

Sound through the air

A clap sends a wave of pressure rippling out through the air to your ear. The air molecules jiggle back and forth in place and pass the disturbance along; nothing blows across the room, yet the sound still reaches you.

Ocean waves

Far out at sea, waves can race for thousands of kilometres, carrying enormous energy, while the water mostly circles in place. Only near the shore, where the wave finally breaks, does the water rush forward.

Glossary — the 10 words that unlock it

Wave

What it means
A disturbance that travels and carries energy without carrying matter along.
Why it matters
It explains how ripples, sound, and light move energy from place to place.
Example
A ripple spreading across a pond is a wave.
Key question
Does a wave carry the water along with it?

Wavefront

What it means
The leading edge of a wave, joining points disturbed at the same moment.
Why it matters
For ripples it is the expanding circle you see racing outward.
Example
Each ring of a pond ripple is a wavefront.
Key question
What shape is the wavefront of a ripple from a single splash?

Wavelength

What it means
The distance between one crest of a wave and the next.
Why it matters
It is one of the basic measures of a wave, linked to speed and frequency.
Example
Ocean swells can have wavelengths of many metres.
Key question
What does a shorter wavelength mean for the crests?

Frequency

What it means
How many wave crests pass a point each second, measured in hertz.
Why it matters
It sets the pitch of a sound and, with wavelength, the wave's speed.
Example
A 2 Hz ripple sends out two rings every second.
Key question
What unit is frequency measured in?

Amplitude

What it means
The strength or height of a wave, how far the medium swings from rest.
Why it matters
It carries the wave's energy, and it fades as a ripple spreads out.
Example
A big splash makes a high-amplitude ripple.
Key question
What does the amplitude of a wave represent?

Medium

What it means
The material a wave travels through, such as water or air.
Why it matters
The medium bobs in place while the wave passes through it.
Example
Water is the medium for pond ripples.
Key question
Does the medium travel along with the wave?

Wave speed

What it means
How fast a wave travels, equal to frequency times wavelength, v = f λ.
Why it matters
It is usually fixed by the medium, so f and λ trade off against each other.
Example
Sound travels at about 340 m/s in air.
Key question
What two quantities multiply to give the wave speed?

Energy transfer

What it means
The carrying of energy from one place to another by a wave.
Why it matters
It is what a wave really moves, even though the medium stays put.
Example
An ocean wave delivers energy to the shore.
Key question
What does a wave transfer without moving matter?

Crest and trough

What it means
The highest and lowest points of a wave.
Why it matters
The spacing between crests is the wavelength; their height is the amplitude.
Example
A ripple's bright rings mark its crests.
Key question
What is the distance between two crests called?

In the picture

What it means
A visual flourish Kinetica draws, echoing the physics rather than simulating it.
Why it matters
The impact ripples are drawn for effect, labelled honestly as in the picture.
Example
The spreading rings are in the picture, not the disc's motion.
Key question
Are the ripples part of the motion or a drawn effect?

The physics, beyond the game

Every wall strike in Kinetica sends out a ripple, a tiny window onto how waves work. This FAQ explains what a wave really carries, why the medium stays put, how wavelength, frequency, and speed connect, and where waves show up all around us.

What is a wave in simple terms?
ConceptualWhatcomplexity 2

A wave is a disturbance that travels and carries energy from one place to another, without carrying the material it moves through along with it. Drop a stone in a pond and a ring of ripples spreads outward: that ring is a wave. The water itself does not flow to the bank — it just bobs up and down as the ripple passes. It is the disturbance, and the energy it carries, that travels.

Does a wave carry matter or just energy?
ConceptualWhethercomplexity 3

Just energy. This is the key idea about waves: they transport energy across a medium while the medium stays roughly in place. A floating leaf on a rippled pond bobs up and down but does not drift to the shore, proving the water is not travelling with the wave. The same is true of sound in air and of ocean swells far from land — energy races along while the material only jiggles in place.

Why does the water only bob up and down?
ConceptualWhycomplexity 3

Because a wave passes the disturbance from one patch of water to the next, rather than pushing the whole pond forward. As a ripple arrives, each patch of surface rises and falls, nudging its neighbour to do the same a moment later, and then settles back. The up-and-down motion is handed along the surface, so the wave travels outward even though no single bit of water makes the journey.

What are wavelength, frequency, and amplitude?
ComparativeWhatcomplexity 3

QuantityWhat it measures
Wavelength λThe distance between one crest and the next
Frequency fHow many crests pass each second (hertz)
AmplitudeThe wave's height, or strength
Wavelength and frequency describe the wave's shape and timing and set its speed through v = f λ, while amplitude describes how strong it is and how much energy it carries.

What is the wave equation v = f λ?
ConceptualWhatcomplexity 3

The wave equation says a wave's speed equals its frequency multiplied by its wavelength: v = f λ. Frequency is how many crests pass each second and wavelength is the distance between crests, so multiplying them gives how far the wave advances each second, which is its speed. Because the speed is usually fixed by the medium, raising the frequency forces the wavelength to shrink, and vice versa — they trade off to keep v the same.

Why do ripples fade as they spread out?
ScenarioWhycomplexity 3

Because the wave's fixed amount of energy gets shared around an ever-larger circle. When a ripple is small, its energy is packed into a short ring; as the ring grows, that same energy is spread thinner and thinner along a longer and longer circumference. With less energy per length, the wave's amplitude drops, so the ripple looks weaker the farther it travels, eventually fading away.

What is a wavefront?
ConceptualWhatcomplexity 2

A wavefront is the leading edge of a wave — the line or surface joining all the points that are disturbed at the same instant. For ripples from a single splash, each wavefront is one of the expanding circles you see racing outward. Far from the source, a small piece of a circular wavefront looks almost straight, which is why distant ripples and ocean swells arrive as nearly parallel lines.

Is sound a wave like a ripple?
ComparativeWhethercomplexity 3

Yes, sound is a wave, though it travels through air rather than across water. A clap squeezes the air, sending a ripple of pressure outward; the air molecules jostle back and forth in place and pass the disturbance along to your ear. Like a pond ripple, sound carries energy without carrying the medium across the room, and it has a wavelength, a frequency that sets its pitch, and an amplitude that sets its loudness.

Do bigger impacts make bigger ripples?
ScenarioWhethercomplexity 2

Yes. A harder strike or a heavier stone puts more energy into the disturbance, which shows up as a larger amplitude — taller, stronger ripples. The wavelength and speed depend mostly on the medium rather than the force, so a big splash and a small splash send their rings out at the same speed, but the big splash's rings start much taller and take longer to fade.

What does it mean that the ripples are 'in the picture'?
ConceptualWhethercomplexity 2

It means Kinetica draws them as a visual flourish, echoing the physics of an impact rather than fully simulating a water surface. The rings are honest about being a drawn effect, layered onto the disc's real motion for feel and beauty. Kinetica keeps this label clear so you can tell which parts of what you see come from the simulated physics and which, like these decorative ripples, are choices about how to draw the moment of impact.

Why are ripples circles from a single splash?
ConceptualWhycomplexity 3

Because the disturbance spreads outward equally in every direction across a flat, even surface. Starting from one point, the wave travels the same distance in all directions in the same time, so the set of points it has reached forms a circle that grows steadily. If the surface were uneven, or the source were a long bar rather than a point, the wavefronts would take other shapes, but a point splash on still water gives expanding circles.

How does frequency relate to the pitch of a sound?
ScenarioHowcomplexity 3

For sound, the frequency of the wave is what your ear perceives as pitch. A high frequency, with many pressure crests arriving each second, sounds high-pitched, like a whistle; a low frequency sounds deep, like a drum. The amplitude sets the loudness separately. So a wave's frequency does double duty: with wavelength it fixes the speed, and on its own it determines how high or low a sound seems.

Where do we meet waves in everyday life?
ReflectiveWherecomplexity 3

Almost everywhere. Sound reaching your ears, ripples on a pond, ocean swells, the wobble of a plucked guitar string, and the light from every lamp and screen are all waves. Radio, wifi, and mobile signals are waves too, carrying information through the air. The same handful of ideas — wavelength, frequency, amplitude, and speed — describes them all, which is why understanding one ripple helps you understand a whole world of waves.

How are these wave ideas used in technology?
ReflectiveHowcomplexity 4

Wave physics underpins much of modern life. Musicians and engineers shape sound waves; sonar and ultrasound send waves out and time their echoes to map the seabed or an unborn baby; radio and wifi encode messages onto waves of a chosen frequency; and noise-cancelling headphones add an opposite wave to silence unwanted sound. Mastering wavelength, frequency, and amplitude lets us create, detect, and control waves for countless purposes.

Why is a single impact ripple a good way to learn about waves?
ReflectiveWhycomplexity 4

Because it shows the heart of a wave in one clear picture: a disturbance born at a point, spreading outward as a growing ring, carrying energy while the water only bobs, and fading as that energy thins around the circle. From that one image you can read off the wavefront, the idea of amplitude, the spreading of energy, and the difference between what travels (energy) and what stays (matter) — the foundations every other wave builds on.

Test yourself — a mixed set

Seven question formats, the way Beyond Dictionary serves them. Every question has layered hints — a quick nudge, the reasoning, then a deeper connection — so a wrong answer opens a door, never a dead end. 32 questions across all seven formats — multiple choice, multiple-correct, fill-in-the-blank, match, sequence, read-think-connect, and write-your-own.

Question 1 of 32
MCQ

Key takeaways

  • A wave is a travelling disturbance that carries energy, not matter.
  • The medium bobs in place — a floating leaf rides ripples but does not drift away.
  • A wave has a wavelength, a frequency, and an amplitude, with speed v = f λ.
  • Ripples fade as their fixed energy spreads around an ever-larger circle.
  • Kinetica's impact rings are an honest in-the-picture flourish, not the disc's motion.

🪜 Where this lesson leads

A single ripple opens onto the whole world of waves. Grasp it and you have started exploring:
Wavefronts
Wavelength & frequency
Wave speed v = f λ
Sound & pitch
Reflection & refraction
Interference
Light as a wave
Radio & signals

Keep exploring

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