Physics
Physics
Invisible forces you can play with
An invisible ocean
Air Is Pressing on You
Air has weight, and the whole atmosphere presses down on everything.
Let’s go →A hidden middle
What Keeps Things From Falling Over?
Things stay upright while their centre of gravity stays over their base.
Let’s go →Pressure from below
Why Does Water Push Up?
Buoyancy exists because water pressure is greater at the bottom of an object than the top.
Let’s go →Climbing without a pump
Why Does Water Climb Up a Paper Towel?
Water climbs a paper towel because it grips the fibres more strongly than gravity can pull it back down.
Let’s go →Passing motion along
What Happens When Things Crash?
In a collision, movement is passed between objects and never simply vanishes.
Let’s go →Light, sorted
Where Do Colours Come From?
Colour is which parts of white light an object bounces back at your eyes.
Let’s go →Jostling passed along
Why Does a Metal Spoon Get Hot?
A metal spoon heats up because vibrating atoms pass their jostling along, and metals pass it exceptionally well.
Let’s go →Heavy for its size
What Is Density?
Density is how much mass is squeezed into a given amount of space.
Let’s go →Waves bunched and stretched
Why Does a Siren Change Pitch as It Passes?
A passing siren drops in pitch because its waves arrive bunched while approaching and stretched once leaving.
Let’s go →It never goes anywhere
Where Does Energy Go When Things Stop?
Energy never disappears when something stops; it has simply turned into heat, sound or something else.
Let’s go →Bouncing all the way
How Does Light Go Round a Bend?
Light travels round bends in a fibre by reflecting off the inside walls thousands of times a metre.
Let’s go →Water pushes back
Why Do Things Float?
Things float when the water they push aside weighs more than they do.
Let’s go →Why things stop
What Is Friction?
Friction is the grip between two surfaces that turns motion into heat.
Let’s go →Trading speed for strength
How Do Gears Work?
Gears let you trade speed for force by pairing wheels of different sizes.
Let’s go →The pull you never notice
What Is Gravity?
Gravity is the pull every object with mass has on every other object.
Let’s go →Everything is shaking
What Is Heat?
Heat is the movement of atoms — the faster they jiggle, the hotter it is.
Let’s go →Water breaks the rules
Why Does Ice Float?
Ice floats because freezing forces water molecules into a roomier pattern.
Let’s go →Nothing changes for free
Why Do Things Keep Moving?
Inertia is an object's refusal to change speed or direction on its own.
Let’s go →It makes nothing — it slows
Does a Coat Make You Warm?
A coat does not warm you. It traps air and slows the escape of the heat your body already produces.
Let’s go →Light marching in step
What Makes a Laser Different From a Torch?
A laser differs from a torch because its light is one colour, one direction, and every wave in step.
Let’s go →Bending light on purpose
How Do Lenses Work?
A lens bends light because its curved shape slows different parts of a beam by different amounts.
Let’s go →Trading distance for force
How Do Levers Work?
A lever lets a small push move a big load by trading distance for force.
Let’s go →How big the push is
What Makes a Sound Loud?
Loudness comes from how big the air's squeeze is, not how fast it repeats.
Let’s go →Invisible reach
How Do Magnets Work?
A magnet works because its atoms are all lined up in the same direction.
Let’s go →Our planet is a magnet
Why Does a Compass Point North?
Earth's liquid iron core makes a magnetic field that swings compass needles north.
Let’s go →A very smooth wall
How Do Mirrors Work?
Mirrors work because their surface is smooth enough to bounce light without scrambling it.
Let’s go →Mass times speed
Why Are Heavy Things Hard to Stop?
Stopping something depends on both its mass and its speed, and spreading the stop over time reduces the force.
Let’s go →Air shoved out of the way
How Does a Parachute Slow You Down?
A parachute slows a fall by making you shove far more air aside, and that air pushes back hard.
Let’s go →A reliable swing
Why Does a Pendulum Keep Time?
A pendulum keeps time because its swing length depends only on the string, not the size of the swing.
Let’s go →Counting wiggles
What Makes a Sound High or Low?
Pitch is how fast something vibrates — fast means high, slow means low.
Let’s go →Force, spread out
What Is Pressure?
Pressure is force divided by area — a small area concentrates the same push.
Let’s go →Sharing the load
How Do Pulleys Help?
Pulleys split a heavy load across several rope sections so each pull is lighter.
Let’s go →Newton's third law
Every Push Has a Push Back
Forces always come in pairs — push anything and it pushes you back.
Let’s go →Same family, different size
Is Radio Really a Kind of Light?
Radio is genuinely light, just with waves metres long instead of fractions of a millimetre.
Let’s go →The same climb, stretched out
Why Are Ramps Easier?
Ramps make lifting easier by spreading the same climb over a longer distance.
Let’s go →Light coming back
Why Can You See Yourself?
Reflection is light bouncing off a surface at the same angle it arrived.
Let’s go →Light changing lanes
Why Does a Straw Look Bent?
A straw looks broken because light bends when it leaves water and enters air.
Let’s go →Pushing in time
Why Does One Note Rattle the Window?
Resonance happens when a sound matches something's natural rhythm, so every wave adds to the last.
Let’s go →Light in a straight line
Why Do Shadows Happen?
A shadow is the place light could not reach because something was in the way.
Let’s go →Sun overhead
Why Are Shadows Short at Noon?
Shadow length depends on how high the Sun is — highest at noon, so shortest then.
Let’s go →A thin film of water
Why Is Ice So Slippery?
Ice is slippery because its surface always carries a thin film of liquid water to slide on.
Let’s go →Air, pushed
How Does Sound Travel?
Sound travels as a squeeze passed from air molecule to air molecule.
Let’s go →Squeeze and stretch
What Does a Sound Wave Look Like?
A sound wave is alternating bands of squeezed and spread-out air travelling along.
Let’s go →Nothing is pushing it out
Why Does the Water Stay in the Bucket?
Swung water stays in because it keeps moving straight while the bucket curves into its path.
Let’s go →Storing a push
How Do Springs Work?
A spring stores energy when squashed and gives it back when released.
Let’s go →Rubbed the wrong way
Why Do You Get Shocks?
Static shocks happen when rubbing moves electric charge, and it jumps back all at once.
Let’s go →A skin made of pulling
Why Does a Paperclip Float on Water?
A paperclip floats because water molecules cling to each other, giving the surface a skin that resists being broken.
Let’s go →Empty space cannot push
What Does Nothing Actually Do?
A vacuum does nothing at all; the interesting effects all come from the pressure of whatever surrounds it.
Let’s go →Wobbling back to the middle
Why Do Things Vibrate?
Vibration happens when something springy is pushed out of shape and overshoots on the way back.
Let’s go →Rolling beats dragging
Why Are Wheels So Good?
Wheels work because rolling replaces sliding friction with almost none.
Let’s go →