Newton's second law of motion | Forces and Newton's laws of motion | Physics | Khan Academy

Calculating Acceleration with Force and Mass00:03:31

The unit of force is the Newton (N), which is equivalent to 1 kilogram-meter per second squared (kg·m/s²). An example calculation demonstrates that if a force of 10 Newtons acts on a 2-kilogram mass, the acceleration will be 5 meters per second squared.

Direct Proportionality of Force and Acceleration00:05:40

Doubling the force applied to an object, such as increasing it from 10 Newtons to 20 Newtons on a 2-kilogram mass, results in a doubling of the acceleration, from 5 m/s² to 10 m/s². This illustrates the direct proportionality between force and acceleration.

Inverse Proportionality of Mass and Acceleration00:06:55

If the mass of an object is doubled while the force remains constant, the acceleration will be halved. This demonstrates that a larger mass requires more force to achieve the same acceleration, or for a given force, a larger mass will accelerate less.

Introduction to Newton's Second Law00:00:00

Newton's First Law states that an object maintains constant velocity unless acted upon by a net force. Newton's Second Law explains how a net force affects this constant velocity, providing the famous formula Force (F) equals Mass (m) times Acceleration (a).

Understanding Force, Mass, and Acceleration00:01:14

Newton's Second Law shows that acceleration is directly proportional to the applied net force and inversely proportional to the mass of the object. Both force and acceleration are vector quantities, meaning they have both magnitude and direction.

Mass vs. Weight00:02:29

Mass is a measure of the amount of 'stuff' in an object, while weight is the force exerted on that mass by gravity. Newton's Second Law highlights the simplicity of the universe's classical laws, as the relationship between force, mass, and acceleration is a straightforward proportionality.