Inertia

• Define inertia and understand its role in an object's motion.

• Explain Newton's First Law of Motion, also known as the law of inertia.

• Describe the relationship between the mass of an object and its inertia.

• Identify unbalanced forces like friction and gravity that overcome an object's inertia.

Key Vocabulary

Inertia

An object's tendency to resist a change in its state of motion, whether at rest or moving.

Mass

The measure of an object's inertia, indicating how much it resists changes in motion when force is applied.

Force

Any push or pull that can cause an object with mass to change its velocity and overcome inertia.

Friction

The force that acts between materials in contact and always opposes the direction of motion or intended motion.

Gravity

The force that attracts an object towards the center of the Earth, causing it to accelerate downwards.

What is Inertia?

• Inertia is an object's tendency to resist any change in its motion.

• All objects have inertia, whether they are stationary or moving.

• It is the core idea behind Newton’s First Law of Motion.

• This law states that motion only changes with an unbalanced force.

Inertia and Mass

• An object's inertia is directly related to its mass, which measures inertia.

• ​Objects with greater mass have greater inertia and are harder to move.

• For example, it’s easier to push one person on a skateboard than two.

• This is because there is less mass and therefore less inertia to overcome.

Friction

• An unbalanced force is required to change an object’s motion.

• Friction is a force that works against motion between touching surfaces.

• It slows a skateboard as the wheels rub against the pavement.

Gravity

• Gravity is an unbalanced force that pulls objects toward one another.

• The Earth’s gravity pulls everything on or near it downward.

• Gravity is what pulls a skateboarder back to the ground after a jump.

• Inertia is an object's resistance to any change in its motion.

• An object's motion only changes when an unbalanced force acts on it.

• An object’s inertia depends on its mass; more mass means more inertia.

• Due to inertia, you move forward when a car suddenly stops.