Area 03
Kinematics
How mechanisms move: gears, links and cams
Kinematics describes motion: positions, paths and speeds. It shows how one movement can be turned into another.
What you will learn
- How gears change speed and direction
- How a gear ratio trades speed for force
- How linkages change rotation into back-and-forth motion
- How to follow the path of a moving point
Example experiments
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Mesh a small gear with a big one and count the turns of each.
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Build a crank and slider and watch the piston move.
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Change the length of a link and see how its path changes.
Things you can build
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A gearbox for a slow, strong winch
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A piston driven by a crank
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A windscreen wiper mechanism
These examples show the kind of work in this area. The published lessons may differ.
Try a small model
These small models run right here in your browser and keep working offline once the page has loaded. They are simplified teaching models, not the MEKALUMI simulation engine.
Tip: drag the left gear to turn it by hand.
Gear train
Change the number of teeth on each gear. Watch how the speed and the turning force change.
- Gear ratio
- 1 : 2
- Output speed
- 15 rpm · 2× slower
- Turning force
- × 2
- Direction
- Opposite to the motor
When a small gear drives a big one, the big gear turns more slowly but with more force. Winches, bicycles and clocks use this idea.
Model: ideal gears without friction or slipping. Motor speed: 30 rpm.
What the simulation simplifies
- Kinematics studies motion, often without asking which forces cause it.
- Parts are assumed to fit perfectly, without gaps or play.
Every simulation simplifies reality. Knowing how it does so is part of learning engineering.
Links to school subjects
Mathematics (geometry and ratios), physics, design and technology
Connections to other areas
Kinematics builds on mechanics and is essential for robotics.
Good to know
On a bicycle, the chain and gears of different sizes trade speed for force when you ride uphill.