1. SACE Stage 1 Conceptual Physics 3. Newton’s First Law of Motion - Inertia

2. Newton’s Law of Inertia Every object continues in its state of rest, or of motion in a straight line at constant speed unless it is compelled to change that state by forces exerted upon it. Every object continues in its state of rest, or of motion in a straight line at constant speed unless it is compelled to change that state by forces exerted upon it.

3. Newton’s Law of Inertia

4. Newton’s Law of Inertia – Question 1 If suddenly the force of gravity of the sun stopped acting on the planets, in what kind of path would the planets move? If suddenly the force of gravity of the sun stopped acting on the planets, in what kind of path would the planets move?

5. Newton’s Law of Inertia – Question 1 Answer If suddenly the force of gravity of the sun stopped acting on the planets, in what kind of path would the planets move? If suddenly the force of gravity of the sun stopped acting on the planets, in what kind of path would the planets move? The planets, like any objects, would move in a straight- line path if no forces acted upon them. The planets, like any objects, would move in a straight- line path if no forces acted upon them.

6. Mass – A Measure of Inertia Mass is not Volume Volume is a measure of space. Measured in m 3. Mass is not Volume Volume is a measure of space. Measured in m 3. Mass is not Weight Weight is a measure of the gravitational force on an object. Measured in N. Mass is not Weight Weight is a measure of the gravitational force on an object. Measured in N.

7. Mass – A Measure of Inertia Mass is the quantity of matter in a body. Mass is the quantity of matter in a body. 1 Kg Weighs 9.8N 1 Kg Weighs 9.8N

8. Review According Newtons First law of Motion – The Law of Inertia – every object continues in its state of rest or of motion in a straight line at constant speed unless forces cause it to change its state. According Newtons First law of Motion – The Law of Inertia – every object continues in its state of rest or of motion in a straight line at constant speed unless forces cause it to change its state.

9. Review Inertia is the resistance an object has to change in its state of motion. Inertia is the resistance an object has to change in its state of motion. Mass is a measure of Inertia. Mass is a measure of Inertia. Mass is not the same as Volume. Mass is not the same as Volume. Mass is not the same as Weight. Mass is not the same as Weight. The mass of an object depends on the amount and type of matter in it, but does don’t depend on the location of the object. The mass of an object depends on the amount and type of matter in it, but does don’t depend on the location of the object. The Weight of an object is the gravitational force on it and depends on the location. The Weight of an object is the gravitational force on it and depends on the location.