The coin and the feather sim
Air pushes back on anything moving through it, and the push (air resistance) grows with speed.
The coin and the feather · covers the GCSE, IGCSE, O-Level topic
What the sim shows
Air pushes back on anything moving through it, and the push (air resistance) grows with speed. The feather is very light for its size, so air resistance soon equals its weight: it stops speeding up and drifts down at about 0.58 m/s, taking 0.99 s to fall 55.00000000000001 cm. The coin is heavy for its size; in the same time it barely notices the air (0.333 s). Pump the air out and there is nothing to push back: both fall with the same acceleration g and land together, after 0.33 s. All objects fall with the same acceleration when there is no air resistance. The pumped-out tube is taken as a perfect vacuum. Taking g = 10 m/s². Shown at 0.25× speed.
- The gauge: air pressure in the tube
- Right: distance against time, and landing times
Use it in your lessons
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