Speed of sound by echo sim
Clap in front of a wall, get in time with the echoes and time a run of them with a stopwatch, work out v = 2d ÷ t and see why one echo is too short to time by hand; then time a pulse between two microphones in air, water and steel with v = d ÷ t and compare the three speeds on one graph.
Sound · covers the O-Level, IGCSE, GCSE topic
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
- Electric field patterns simSwitch on an EHT supply joined to electrodes in a dish of castor oil and watch semolina grains line up into the field pattern of a point, a charged sphere, two points or two parallel plates; drag the electrodes, show field lines running from + to −, and drop in a small + or − test charge to see the force on it.
- Energy resources: power a town simDrag the faders on a model town's control desk to switch on coal, gas, nuclear, biofuel, geothermal, hydroelectric, wind, solar and tidal power, change the wind, the sky and the hour, and see hour by hour whether the supply meets the town's demand, with scores for hours met, CO₂, renewables and rough cost; save your mixes to a table and sort the resources by renewable, from the Sun and available at any hour.
- Evaporation and boiling simWeigh a dish of water or ethanol on a balance as it evaporates, changing the temperature, the surface area and a desk fan's air speed; watch a wet-bulb thermometer cool below a dry one; then heat water on a hotplate until bubbles form all through it and the temperature stays at the boiling point.
- Floating, sinking and upthrust simLower a cylinder on a newton-meter into water, salt water or cooking oil from a displacement can that spills into a beaker on a balance: watch the reading fall as the upthrust grows, find U = weight in air − reading in the liquid, predict float or sink from the densities, and see a wooden block float deeper in oil and higher in salt water; cards show a hydrometer and a steel boat.
- Magnetic field of bar magnets simPlot the field round a bar magnet the classic way, moving a plotting compass and marking a pencil dot at each end of its needle, then sprinkle iron filings, put two magnets N–N (finding the neutral point X) and N–S, and add the Earth's field to see where it cancels the magnet's.
- Magnetic field of a wire and a solenoid simPass a current up a wire through a card ringed with plotting compasses and iron filings, reverse it and raise it with a rheostat, then thread a coil through the card and see its field look like a bar magnet's, with its N end found by the right-hand grip rule and made stronger by more current, more turns and an iron core.