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cosmic dust
Dec5-12, 08:10 AM
P: 123
Inertia is that "process" (it's not really a process but a fundamental principle of nature). Inertia is the ressistance of objects to some change in their state of motion. That is, if an object is still, it tendes to remain still and if it is moving with constant (in magnitude and direction) velocity, it tends to keep that velocity stable. When you see the bottle going backwards when the train accelerates, that happens because the bottle was moving with a constant velocity which (due to inertial) tends to keep, so when the train accelerates the bottle stays behind. The same principle applies to every object with mass.