Topic · 27 games
A wave carries energy and a shape from place to place while the material only moves back and forth. Its frequency, wavelength, and speed are tied together: v = f·λ, T = 1 ÷ f.
PLAY NOW · 65
A wave carries a shape and energy along, while the rope only moves up and down. Time a pulse, watch a ribbon stay put, read the amplitude, add two pulses that meet, and catch an echo.
PLAY NOW · 66
A pebble's ripple shrinks as its ring grows, because the same energy is shared around a longer and longer ring. Find the height far away, the energy per metre, the distance where it drops to 1 cm, and compare a straight wave.
PLAY NOW · 67
A wave carries energy along a rope to an absorber at the far end. Double the amplitude, double the frequency too, work out the watts, find the swing that keeps the power the same, and try a heavier rope.
PLAY NOW · 68
A bar dips into a tank 8 times a second and sends straight ripples along it. Count the gaps between crests, read a photo at half size, find the speed with v = f·λ, slow the ripples over a shallow end, and time them across.
PLAY NOW · 69
A motor shakes one end of a rope and fills it with waves. Count them to find the wavelength, link it to the frequency with v = f·λ, shake faster, time the period at a bead, and test a bigger amplitude.
PLAY NOW · 70
A string's note is its frequency, f = v ÷ (2·L). Find the note of a guitar string, halve it for an octave, press it to play another note, tighten it, and time one vibration, with a tuner to check.
PLAY NOW · 71
A strobe lights a moving wave for an instant, again and again. Flash once per cycle and it freezes; a little off and it creeps at f − f_s. Freeze a wave, read its creep, measure a frequency, stop a wheel, and find a speed.
PLAY NOW · 72
A surfer waiting in one place rises on every crest that passes, once every period T = λ ÷ v. Time the wait, count waves a minute, find the swell's speed and spacing, and turn the period into a frequency.
PLAY NOW · 73
The sea at a harbour rises and falls with a period of about 12 h 25 min. Time four tides, find the low tide, count highs in a day, see why high tide comes 50 minutes later each day, and find the tide's wavelength.
PLAY NOW · 74
A pulse on a tight rope runs at v = √(F ÷ μ): faster with more tension, slower on a heavier rope. Find a pulse's speed, see why four times the tension only doubles it, find the tension a speed needs, and time a pulse across a rope.
PLAY NOW · 75
A tsunami is so long that the whole depth of the sea moves with it, and its speed is v = √(g·h). Find its speed over a deep ocean, turn it into km/h, time a 2000 km crossing, see it slow near the shore, and read the depth from a speed.
PLAY NOW · 76
Shake a slinky side to side and each coil moves across it: a transverse wave. Push and pull it and each coil moves along it, bunching into compressions: a longitudinal wave. Find the angle of a coil's motion, the spacing of compressions, and their speed.
PLAY NOW · 77
An earthquake sends a fast longitudinal P wave and a slower transverse S wave. The gap between them tells a station how far away the quake was. Find that distance, the arrival times, the S wave's shake, and its speed.
PLAY NOW · 78
An echo is sound that bounced back, so it travels the distance twice: d = v·t ÷ 2. Sound the sea floor with sonar, find a bat's moth, time a cliff's echo, measure the speed of sound in sea water, and find a shoal of fish.
PLAY NOW · 79
A ripple leaves a wall at the same angle it arrived. A pulse on a rope comes back upside down from a clamped end and upright from a free end. Find the angle out, aim a bank shot, predict each pulse's way up, and time a return trip.
PLAY NOW · 80
Waves slow down in shallow water. Their frequency stays the same, so their wavelength shrinks, and if they arrive at an angle they bend: refraction. Find the new wavelength, the frequency, the angle, the speed, and the depth over a sandbank.
PLAY NOW · 81
Light is slower in water, so it bends as it crosses the surface: n₁·sin θ₁ = n₂·sin θ₂. A fish looks shallower than it is. Find a fish's real depth, a laser's angle in water, where to aim a spear, a liquid's index, and the critical angle.
PLAY NOW · 82
Two speakers playing the same note fill a room with loud and quiet spots. It is quiet where one is half a wave farther than the other: Δd = (n + ½)·λ. Find quiet and loud spots, a frequency, a wavelength, and what a reversed speaker does.
PLAY NOW · 83
Two notes close in pitch drift in and out of step, so the sound swells and fades |f₁ − f₂| times a second. Tuners listen for the beats to slow and stop. Find a beat rate, a retuning, the time between beats, sharp or flat, and a pitch gap.
PLAY NOW · 84
Waves spread out after passing a gap, most when the gap is about one wavelength. Far behind it, the first calm direction is sin θ = λ ÷ a. Find calm directions, the gap that calms a boat, a wavelength, and when waves fill the whole harbour.
PLAY NOW · 85
Light through a narrow slit spreads into a bright band with dark bands either side. The first dark band is y = λ·L ÷ a from the centre. Find a dark band, the central band's width, a slit's width, a laser's wavelength, and the second dark band.
PLAY NOW · 86
A moving siren squeezes its sound waves together ahead and stretches them behind, so you hear it higher as it comes and lower as it goes: f' = f·v ÷ (v ∓ v_s). Find the pitch coming and going, an ambulance's speed, a siren's note, and an octave.
PLAY NOW · 87
Each paddle sends out a ring from where the duck is, so the rings crowd together ahead and spread out behind: λ' = (v ∓ v_s) ÷ f. Faster than its ripples, the duck makes a V-shaped bow wave. Find spacings, a speed, a paddling rate, and a bow wave's angle.
PLAY NOW · 88
Decibels count powers of ten: L = 10·log(I ÷ I₀), so every 10 dB is ten times the intensity, and twice as far away is about 6 dB quieter. Find the level of ten speakers, the drop with distance, an intensity ratio, a level, and a distance.
PLAY NOW · 89
A bottle is a pipe closed at one end: its air column holds a quarter of a wave, so f = v ÷ 4L. Pour in water and the column shortens, so the pitch rises. Find a bottle's note, the note after pouring, a column length, how much to pour, and the next note up.
PLAY NOW · 90
Radio, Wi-Fi, and microwaves are waves that travel at 3 × 10⁸ m/s. Use λ = c ÷ f to find their wavelengths, size a quarter-wave antenna, space a microwave oven's hot spots, and see why AM masts are so tall.
PLAY NOW · 91
Sound is a wave of squeezes in the air, travelling at 340 m/s. Slow a note down to see its wavelength and period, then use the speed of sound to find a storm from its thunder and a cliff from its echo.
11 games
Position, velocity, acceleration, and gravity.
2 games
Units, SI prefixes, and scientific notation.
3 games
Rearranging formulas: inverse operations and unit checks.
3 games
Vector addition, displacement, and forces.
3 games
Right triangles, inverse functions, and the unit circle.
3 games
Horizontal and angled launches: two motions at once.
3 games
Uniform circular motion, angular velocity, and centripetal force.
3 games
Newton's law of universal gravitation, weight, orbits, and Kepler's laws.
3 games
Force equilibrium, cable tension, torque, and support reactions.
5 games
Torque, lever arms, tipping, and angular acceleration.
3 games
Centre of mass, balance points, composite objects, and toppling.
9 games
Density, buoyancy, floating, and pressure under water and in the air.
3 games
Flow, Bernoulli's principle, jets, pipes, and lift.
10 games
Amplitude, period, frequency, pendulums, springs, energy, and resonance.
10 games
Electric charge, electrons, and the forces between charges.
16 games
Voltage, current, resistance, and the energy circuits carry.