Inertia
The inherent property of an object by virtue of which it resists any change in its state of rest or uniform motion along a straight line.
What is Inertia?
The property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.
Key points
- Define inertia.
- Explain Newton's First Law of Motion.
- Relate inertia to mass.
- Differentiate between inertia of rest and inertia of motion.
Common exam trap
Confusing inertia with force.
Definitions
- Term
Inertia
- Meaning
The property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force.
- Term
Newton's First Law of Motion
- Meaning
Every body continues in its state of rest or of uniform motion in a straight line, unless compelled to change that state by forces impressed upon it.
- Term
Mass
- Meaning
A measure of the amount of matter in an object, and also a measure of its inertia.
Learning objectives
Define inertia.
Explain Newton's First Law of Motion.
Relate inertia to mass.
Differentiate between inertia of rest and inertia of motion.
Provide examples of inertia in everyday life.
Prerequisites
Understanding of 'state of motion'
Concept of 'force'
Basic understanding of 'mass'
Common mistakes
Confusing inertia with force.
Assuming inertia changes with velocity.
Not relating inertia directly to mass.
Forgetting that inertia applies to both rest and motion.
Keywords
Inertia
Newton's First Law
Law of Inertia
Mass
State of Rest
Uniform Motion
Resistance to Change
Practice preview
A car is moving with uniform velocity. Which of the following statements is correct regarding the forces acting on the car?…
medium
A body is at rest. According to Newton's first law of motion, it will remain at rest unless:…
medium
A passenger in a moving bus tends to fall forward when the bus suddenly brakes. This is an example of:…
easy