Newton's First Law of Motion

Fundamentals of Newton’s First Law of Motion

• Newton’s First Law, also known as the Law of Inertia, dictates that an object will maintain its state of motion unless acted upon by an unbalanced force.
• Inertia is a property of matter that resists changes in its state of motion. The amount of inertia an object possesses is directly proportional to its mass.

Understanding the Real-World Application

• Everyday occurrences such as a passenger lurching forward when a vehicle abruptly stops is an example of Newton’s First Law in action, illustrating inertia’s impact on motion in our daily life.
• The force exerted by a table to hold up a book, showing that forces are normally in pairs, is another example of how this Law influences everyday events.

Newton’s First Law and Balanced/Unbalanced Forces

• When forces acting on an object are balanced (i.e. resultant force equals zero), that object continues to be in its original state of motion. It might be at rest or moving at a constant speed in a straight line.
• An object’s motion only changes when unbalanced, or net forces, act on it. This change in motion could be a change in the object’s speed, direction, or both.

Implications of Newton’s First Law

• Newton’s First Law implies that it is natural for an object to continue in its state of motion and that it requires an unbalanced force to change that state.
• In the absence of friction and air resistance, an object set in motion will continue to move at the same speed and in the same direction indefinitely.