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You know that the force of friction depends on the nature of the surfaces in contact. Does it also depend on how hard the surfaces press each other? Is the friction on an object about to move larger than the friction after motion begins? Is friction on a rolling object less than on a sliding object? Find answers and create an infographic. Such observations help explain why the invention of the wheel was a major milestone.
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Friction increases when surfaces press harder. The friction just before an object starts to move (static) is usually larger than the friction once it is moving (kinetic). Rolling friction is much smaller than sliding friction — which is exactly why wheels make moving loads so much easier, making the wheel a major milestone. Present these findings as a labelled infographic with simple experiments.
