Physics: Age 13

18 illustrated Physics lessons for Age 13.

Small and large vibrating surfaces A small surface vibrates quickly and makes a high pitch, while a large surface vibrates more slowly and makes …
Why Space Is Silent Sound is a vibration that has to be passed from particle to particle, so it needs a material such as air, wate…
Sunlight's 8-Minute Journey In empty space, light travels in a straight line at about 300,000 kilometres every second. Even at that speed,…
Series and parallel circuits In a series circuit, the same current flows through every part of one single loop. In a parallel circuit, the …
White Light Through a Glass Prism A narrow white beam enters a clear triangular glass prism from the left. Inside the glass it bends, and when i…
Geostationary satellite A geostationary satellite orbits in step with Earth's rotation, so it stays above the same spot on the equator…
Sail, keel, and forward motion Wind moving past the curved sail creates a force that points at an angle from the sail. The keel in the water …
Hot Rock Moves Earth's Plates Rock deep in the mantle gets heated, becomes lighter, and rises. Cooler rock sinks, and this slow churn drags …
Drone Camera Stays Level A drone's body can tilt as it moves, but its camera can stay level. A fast-spinning gyroscope senses the tilt,…
Hollow hull and solid marble A ship's hull is mostly air-filled space, so the whole ship pushes aside more water than it weighs. A solid gl…
Signals Under the Sea Digital information moves as fast pulses through cables. Some of these cables run across the ocean floor betwe…
Spinning Cloud Becomes a Star A huge cloud of gas and dust pulls inward and begins to spin. As it shrinks, it flattens into a disk, and its …
Arms In, Spin Faster When a spinning person pulls weights closer to their body, the spin gets faster. Moving mass inward makes the …
Light Bending at a Glass Surface A ray of light travels through the air and meets the flat face of a glass block. Part of the light bounces bac…
Snow Layers and Cup Crystals Inside snow, some layers are warmer than others. That difference slowly changes star-shaped crystals into loos…
Falling in Two Tubes In a tube with no air, a feather and a lead ball fall together. In open air, the feather falls more slowly tha…
Feather colors from grains and air pockets Some feather colors come from pigments, which absorb most light and reflect one color. Other feather colors co…
Series Circuit and Parallel Circuit On the left board a single loop of wire joins the battery to both bulbs. On the right board the wire splits in…