Physics Basics · Professor Erklärbär

15:32

Episode 1

Speed & Acceleration Explained

What you will learn

motion needs a frame of reference – are you sitting still on the train or doing 120 km/h?
measuring distance and time – and why you measure more than once
calculating speed: v = s / t, in m/s and km/h (times 3.6)
average vs. instantaneous speed: speedometer, speed cameras, average-speed checks, running pace
reading a distance-time graph: steep, flat, horizontal
acceleration: a = Δv / Δt – braking counts too
reaction distance: why 2 seconds on your phone means almost 28 metres driving blind
the three most common mistakes

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13:38

Episode 2

Forces Explained

What you will learn

recognising a force by its effect: deformation or a change in motion
measuring forces: spring balance, newtons – and why 100 g of chocolate weighs about 1 N
drawing and adding force arrows (tug of war: 600 N against 500 N)
inertia: why you lurch forward in the bus – seat belts and the ketchup bottle
friction: static, sliding and rolling friction – and why friction is useful
balanced forces: even at a constant 100 km/h
forces come in pairs: skateboard, swimming, rocket
F = m · a: the skateboarder with 50 kg and 100 N
the three most common mistakes

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11:46

Episode 3

Levers & Torque Explained

What you will learn

pivot and lever arm – why the handle is on the outside
torque M = F · a: a wheel nut at 120 N·m and the extended wrench
the law of the lever on a seesaw: 300 N at 2 m against 750 N at 0.8 m
types of levers: scissors, wheelbarrow, nutcracker – and your forearm
the golden rule of mechanics: less force means more distance
the pulley system: lifting 800 N with 200 N
centre of gravity and tipping: crane with counterweight, roof box
the three most common mistakes

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11:37

Episode 4

Gravity Explained

What you will learn

everything attracts everything – even you and your phone
mass (kg) and weight (N) – and why “I weigh 60 kg” is really your mass
F_G = m · g: Earth ≈ 10 N/kg, Moon 1.62, Jupiter 24.8
hammer and feather on the Moon – without air everything falls equally fast
air resistance: skydivers at 200 km/h and at 20 km/h
10 m/s faster every second – your phone hits the floor in 0.4 s
weightless in the ISS – although gravity there is almost 90 %
the three most common mistakes

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11:27

Episode 5

Energy, Work & Power Explained

What you will learn

forms of energy – and what a joule has to do with a bar of chocolate
work W = F · s: why holding still is no work, even if it is exhausting
potential energy m · g · h – from the bookshelf to the pumped-storage power plant
kinetic energy ½ · m · v²: twice as fast, four times the energy
conservation of energy: roller coaster, pendulum and trampoline
efficiency: electric motor 80 %, your muscles about 25 %
power P = W : t – 180 W walking, 540 W running
the three most common mistakes

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12:58

Episode 6

Pressure Explained

What you will learn

p = F : A – why the bed of nails doesn't hurt
stiletto heel vs. elephant: 60 bar vs. 1 bar
density ρ = m : V – and what a cube is made of
in water: about 1 bar more every 10 m, only the depth matters
air pressure: we live at the bottom of an ocean of air
straw and suction cup: you don't suck, the air pushes
hydraulics: lift a car with the force for 10 kg
the three most common mistakes

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11:33

Episode 7

Buoyancy Explained

What you will learn

a stone on a spring scale: 20 N in air, 12 N in water
where buoyancy comes from – the pressure is greater at the bottom
Archimedes and “Eureka”: buoyancy = weight of the displaced water
sinking, hovering, rising, floating – a comparison of forces
the iceberg: almost 90 % under water · the Dead Sea carries you
the clay boat – and why a steel ship floats
submarine, fish, life jacket and hot-air balloon
the three most common mistakes

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14:10

Episode 8

Heat & Temperature Explained

What you will learn

particles in motion: the warmer, the faster
sparkler vs. bathtub: temperature is not heat
Celsius and Kelvin: 0 K = −273.15 °C
expansion joints: a 100 m steel bridge grows by about 6 cm in summer
water is densest at 4 °C – that's why lakes freeze from the top
the temperature stays constant while melting and boiling
conduction, convection, radiation – and the answer to the railing puzzle
thermos flask, down jacket, double glazing
Q = c · m · ΔT: bringing 1 litre of water to the boil takes 335 kJ
the four most common mistakes

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11:29

Episode 9

Sound Explained

What you will learn

everything that sounds vibrates: loudspeaker, tuning fork, guitar string, rice on a drum
alarm clock in a bell jar: no air, no sound – space is silent
the sound wave: compressions travel, the particles only move back and forth
343 m/s in air, 1480 m/s in water – thunder trick: seconds divided by 3 = kilometres
frequency in hertz: concert pitch A = 440 Hz, hearing range 20 Hz to 20 kHz, ultra- and infrasound
amplitude and decibels: +10 dB ≈ twice as loud, above 85 dB damages your hearing
echo, echo sounding and bats
guitar, flute, octave and overtones – where timbre comes from
the three most common mistakes

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11:25

Episode 10

Light & Color Explained

What you will learn

light enters the eye – and takes 8 minutes 20 seconds from the Sun
umbra and penumbra, solar and lunar eclipses
angle of incidence = angle of reflection – and what a mirror really swaps
blind spot: why cyclists should never wait next to a turning truck
refraction: the bent straw and the coin in the cup
total internal reflection: how the internet travels through glass fibres
converging and diverging lenses, magnifier, eye and glasses
prism and rainbow: white light is a mixture of all colours
your screen mixes everything from red, green and blue
the four most common mistakes

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12:43

Episode 11

The Universe Explained

What you will learn

day and night: we are turning – at the equator at more than 1600 km/h
seasons: it is the tilted axis (23.4°), not the distance from the Sun
phases of the Moon, solar and lunar eclipses – and why the Moon turns red
a scale model: Sun = football, Earth = peppercorn 24 m away, Neptune 700 m away
the light-year: a distance of about 9.5 trillion kilometres
Proxima Centauri: 4.2 light-years – 75,000 years for Voyager
stars: red ones are cooler, blue ones hotter – and the Sun is one of them
the Milky Way, billions of galaxies and the Big Bang 13.8 billion years ago
spotting the ISS and GPS satellites
the three most common mistakes

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12:23

Episode 13

Radioactivity Explained

What you will learn

atoms are almost empty: if the atom were a stadium, the nucleus would be a pea
protons, neutrons, electrons – and what isotopes are (C-12 and C-14)
alpha, beta, gamma: paper, aluminium, lead
making radiation visible in a cloud chamber
half-life to play along: 100 dice, sixes drop out
Ötzi and radiocarbon dating: 53 % C-14 → about 5,300 years
radon in the basement, X-rays, CT scans, flights – and why airing helps
radiation protection: distance, shielding, short time
the three most common mistakes

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12:08

Episode 14

Building a Chain-Reaction Marble Run

What you will learn

the plan: every station costs height – that's why a new marble starts at each station
household materials: pool noodles, cardboard, marbles, syringes, ice cubes, mirrors
eleven stations: ramp, dominoes, seesaw, drop tower, loop, hydraulics, float, ice timer, sound track, periscope, spiral funnel
measuring with phyphox: 1 m in 0.8 s → 1.25 m/s, drop tower ≈ 0.45 s, loop start ≈ 20 cm
troubleshooting: at least 5 cm of slope per metre, a wall in the curve, test each station on its own
the challenge: more than 60 seconds run time – Rube Goldberg machines
looking back: the whole physics series in one marble run

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