Free physics resources · Ages 11–18
Feed a hungry alien using projectile physics, bust a few myths, and let the calculators do the boring bits, with every step shown. Free, no sign-up, and nobody marking your answers. Built for GCSE, IGCSE, A Level, AP, IB, HSC and VCE.
Mini game
A small green alien is waiting a set distance away, and it's starving. Pick an angle and a speed, then launch its snack. You can guess your way there, or use the range equation and get it first time. Your call.
Five aliens per round. Finish in 5 shots for three stars. Your best round is saved in this browser only.
R = v2 sin 2θ / g
The first alien is hungry. Take your shot.
Calculators
Type in what you know and they write out the equation, the numbers and the units, so you never lose a "show your working" mark again. Not sure where to start? Hit one of the examples.
Calculator · Ages 14–18
Fill in any three values and leave two blank. Use a minus sign for anything pointing the opposite way.
GCSE · AP Physics 1 · A Level · IB · HSC · VCE
Calculator · Ages 13–18
Add up resistors in series or parallel. Add a battery voltage to get the current and power too.
KS3 · GCSE · high school · AP Physics 2 · A Level
Converter · Ages 11–18
Change km/h to m/s, grams to kilograms, kWh to joules and more, with the conversion factor shown. Fun fact: a cheetah sprinting at 25 m/s is doing 90 km/h. Check it below.
Every level · SI units · standard form
Quiz · Physics myths
Eight things most adults get wrong. Commit to an answer before you peek, and no changing your mind. Predicting first is how every Lernivora lesson starts, because a wrong guess you remember beats a right answer you forget.
Quiz · Ages 11–18 · About 3 minutes
Falling balls, crashing trucks, melting ice, floating astronauts and explosions in space. Challenge your parents too.
Readiness checks
Ten quick questions, no pressure and no grades. You'll get a rank and a short list of topics worth a closer look.
Skill check · Ages 13–15 · About 8 minutes
Units, rearranging equations, standard form, graphs and first forces. Good before GCSE in the UK, high school physics in the USA or Year 10 science in Australia.
Skill check · Ages 15–17 · About 10 minutes
The maths senior physics expects on day one: algebra, trigonometry, vectors, graphs and proportion.
Quick physics answers
Short, exam-ready answers to the things students ask most. Tap one to open it.
The five SUVAT equations describe motion with constant acceleration: v = u + at; s = ut + ½at²; s = vt − ½at²; s = ½(u + v)t; and v² = u² + 2as. Here s is displacement, u is initial velocity, v is final velocity, a is acceleration and t is time. If you know any three, you can find the other two, and the SUVAT solver shows you how.
In series, add them: R = R₁ + R₂ + R₃. In parallel, add the reciprocals: 1/R = 1/R₁ + 1/R₂ + 1/R₃. The total resistance in parallel is always smaller than the smallest single resistor. For example, 4 Ω, 6 Ω and 12 Ω make 22 Ω in series and 2 Ω in parallel. Try it in the resistor calculator.
For a projectile launched and landing at the same height, ignoring air resistance, the range is R = v² sin 2θ / g, where v is the launch speed, θ is the launch angle and g is 9.81 m/s². The longest range is at 45°, and pairs of angles that add up to 90°, such as 30° and 60°, land in the same place. Put it to work by feeding the alien.
Divide by 3.6. One kilometre per hour is 1,000 metres in 3,600 seconds, which is 1/3.6 m/s. For example, 90 km/h ÷ 3.6 = 25 m/s. To go from m/s to km/h, multiply by 3.6. The unit converter handles the rest.
Mass is the amount of matter in an object, measured in kilograms, and it is the same everywhere. Weight is the force of gravity on that mass, measured in newtons: W = mg. On Earth g is about 9.81 N/kg, so a 5 kg mass weighs about 49 N. On the Moon it would weigh about one sixth as much.
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