Gears in Motion
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flagWhat you'll discover
- arrow_forwardShow that meshing gears spin in opposite directions
- arrow_forwardRead a gear ratio like 2:1 and say what it means
- arrow_forwardExplain the trade between speed and turning strength
- arrow_forwardFind gears hiding in everyday machines around you
Teeth that push teeth
A gear is a wheel with teeth around its edge. When two gears mesh, the teeth of one push the teeth of the other, so spinning the first gear makes the second one spin too.
Here is the surprise: the second gear always spins the opposite way! Watch the arrows in the simulation — if the driver turns clockwise, its partner turns counter-clockwise. Add a third gear and the direction flips back again.
Gear ratio: the magic number
Count the teeth! If a small gear with 12 teeth drives a big gear with 24 teeth, the big gear has twice the teeth, so it turns only half as fast. We write this as a 2:1 ratio.
In the sim, switch between 1:1, 2:1 and 3:1 and watch the RPM readouts. RPM means "rotations per minute" — how many full spins a gear makes in one minute.
Speed or strength: pick one
Gears cannot give you extra speed AND extra strength at the same time — it is always a trade. A big slow gear turns with more twisting force, called torque. A small fast gear spins quickly but with less force.
A cyclist climbing the steep hill to Nagarkot shifts to a low gear: the wheels turn slower, but with enough strength to climb. On the flat road back, a high gear trades that strength for speed.
Gears are everywhere
Open up almost any machine and you will find gears: bicycles, clocks, egg beaters, washing machines and the small servo motors used in school robotics kits.
Robot designers add gearboxes to motors because most motors naturally spin very fast but very weakly. A gearbox slows the spin down and multiplies the strength, so a small motor can lift a heavy robotic arm. No gearbox, no lifting!