Inertia
Without a net external force, an object's velocity does not change.
Force and acceleration
For a given mass, a larger net force produces a larger acceleration.
Action and reaction
Forces arise in interacting pairs acting on different objects.
Real motion has multiple forces
Friction, gravity, support forces and applied forces often act at the same time.
This page explains scientific concepts for general learning. It does not replace laboratory safety procedures, professional engineering guidance, or individualized medical advice.