Inertia
Newton’s First Law: The Law of Inertia
Inertia: The resistance to change motion.
- Affected By: Mass and ONLY mass. A the heavier object will ALWAYS have more inertia than a lighter object.
- Type of Quantity: Scalar
So....
- Mass is directly proportional to inertia (the less mass an object has, the less inertia it has).
- The more inertia an object has, the more difficult it is to stop the object or change it’s direction.
- Mass is the measure of an object’s inertia (in kg).
- Inertia is NOT a force.
- An object in motion will stay in motion IN A STRAIGHT LINE WITH CONSTANT VELOCITY unless acted on by another force. An object at rest will stay at rest unless acted on by another force.
You can easily slide a book on the floor because it has little mass so it has little inertia so it doesn’t resistant motion very much. You can’t easily push a car across the floor because it has a large mass so it has large inertia and resists the change in motion more.
If you have a 5 kg object moving at 60 m/s and a 13 kg object at rest, the 13 kg object has more inertia. It is more difficult for you to get the 13 kg object to start moving than it is for you to change the speed or direction of the 5 kg object.
If any question regards inertia in any way, only look at the mass.