Hooke's law sim
Load 50 g masses onto a spring and watch it stretch the same 12.3 mm every time.
Forces: springs and extension · covers the IGCSE, GCSE, O-Level topic
What the sim shows
An ideal spring (k = 40 N/m, unloaded length 60 mm) hangs from a clamp. Each 50 g mass adds 0.49 N of weight (g = 9.81 N/kg) and stretches the spring by the same 12.3 mm, so extension is proportional to force: F = kx. Six masses and the hanger (350 g) stretch it 85.8 mm, still inside the limit of proportionality. The rule reads the spring's length from its top: the unloaded spring reaches the 6.0 cm line, and extension = stretched length − original length (here measured from the unloaded spring, so the 50 g hanger already stretches it 12.3 mm). The load bounces with the spring's own period, T = 2π√(m/k), before it settles. The spring's own mass is ignored.
- Pointer: marks the spring's length on the rule (extension = new reading − 6.0 cm)
- Slotted masses, 50 g each, on a 50 g hanger
- Spring, k = 40 N/m
Use it in your lessons
- Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
- Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
- Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.
Free guide: 12 practicals as sims, and how to run one in a lesson →
Need a version for your exact set-up? Have one made: US$49 a figure in an order of 5.
More physics sims
- Using ammeters and voltmeters simDrag the meters' plugs onto a real bench circuit: put the ammeter in series and the voltmeter across the lamp, red to +, see what really happens when they are wired wrongly (a blown fuse, a dark lamp), pick the range, read the needle to half a division looking straight on, correct a zero error, compare a digital display, and work out the lamp's resistance from your own readings.
- Wiring a mains plug simDrag the brown, blue and green-and-yellow cores onto the terminals of a real three-pin plug seen from the back, tighten the screws, choose the strip length, work out I = P ÷ V and fit the right fuse, clamp the cable grip on the sheath, then run the checks, which name every fault, why it matters and what it would do, and see what earthing does when a live wire touches the metal case.
- Converging lens simSlide the lamp along an optical bench; the screen finds the focused image from 1/f = 1/u + 1/v (real-is-positive).
- Vibrating string loop simDrag through 8 modes of a closed loop: whole waves fit round it, and f = n v / C climbs 105 Hz at a time.
- Specific heat capacity of a solid (or water) simHeat a 1.00 kg block or water with a 12 V immersion heater, read the thermometer each minute, fit a line to your graph and work out c, bare or lagged, by joulemeter or by V, I and a stopwatch.
- Cylinder rolling down a ramp: v² against x simMeasure sin θ with a half-metre rule and set square, time a rolling cylinder (or a trolley) over eight distances, fill the table, plot v² against x and find G ÷ (2 sin θ).