Forces Motion And Energy: Science Terms Explained

Plain-language definitions of every forces motion and energy term your child meets in school, each with kid-friendly explanations, worked examples, and common mistakes to watch for.

Newton's first law

Newton's first law is the rule that an object will stay at rest or keep moving in a straight line at a constant speed unless a net (unbalanced) force acts on it.

Newton's laws of motion

Newton's laws of motion are three basic rules that describe how forces affect the motion of objects, explaining why objects stay still, speed up, slow down, or change direction.

Newton's second law

Newton's second law is the idea that the acceleration of an object depends on the net force acting on it and its mass, usually written as F = m × a, where F is net force, m is mass, and a is acceleration.

Newton's third law

Newton's third law is the idea that whenever one object pushes or pulls on another object, the second object pushes or pulls back with an equal-strength force in the opposite direction.

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