Newton's First Law of Motion
An object remains in a state of rest or of uniform motion in a straight line unless compelled to change that state by an applied force.
What is Newton's First Law of Motion?
The tendency of an object to resist changes in its state of motion. It is a measure of how much mass an object has.
Key points
- Define inertia.
- State Newton's First Law of Motion.
- Explain the relationship between force and changes in motion.
- Identify examples of inertia in everyday life.
Common exam trap
Confusing inertia with force.
Definitions
- Term
Inertia
- Meaning
The tendency of an object to resist changes in its state of motion. It is a measure of how much mass an object has.
- Term
Uniform Motion
- Meaning
Motion with constant velocity, meaning constant speed and constant direction.
- Term
Unbalanced Force
- Meaning
A net force acting on an object that results in a change in its state of motion (acceleration).
Learning objectives
Define inertia.
State Newton's First Law of Motion.
Explain the relationship between force and changes in motion.
Identify examples of inertia in everyday life.
Understand that inertia is a measure of mass.
Prerequisites
Understanding of 'rest' and 'motion'.
Concept of 'velocity' (speed and direction).
Basic understanding of 'force'.
Common mistakes
Confusing inertia with force.
Assuming that an object needs a force to keep moving at a constant velocity (a common misconception from everyday experience where friction is present).
Not distinguishing between balanced and unbalanced forces.
Thinking that inertia is a force itself.
Keywords
Newton's First Law
Inertia
Rest
Uniform Motion
Unbalanced Force
Mass
Practice preview
A passenger in a moving bus suddenly jerks forward when the bus driver applies the brakes. This phenomenon is an illustration of:…
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A spacecraft is moving in outer space far from any gravitational influence. If its engines are turned off, according to Newton's first law, what will happen to the spacecraft?…
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Imagine you are in a train moving at a constant velocity. You drop a ball. According to Newton's first law, where will the ball land relative to you?…
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