1) Newton's first law of motion states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. 2) Inertia is an object's resistance to changes in its motion. An object's inertia depends on its mass - the greater the mass, the greater the inertia. 3) Tosh is correct - inertia depends on an object's mass, not its speed. The greater the mass, the greater the inertia.

1. Warm - Up The rate of change of velocity is known as: A. momentum. B. speed. C. acceleration. What is force? A push or pull that usually causes a change in an objects motion.

2. 7-2 – Newton’s 1st DescribeNewton’s first law of motion and its relation to inertia.

3. Mass & Inertia Inertia is the resistance an object has to a change in its state of motion. Mass has an affect on inertia. Mass is directly proportional to inertia. An object that has a greater mass has a greater tendency to maintain its state of motion. Increased mass, increased inertia. Which has more inertia? Basketball or golf ball Pencil or textbook Earth or you

4. If friction could be eliminated

5. Newton’s 1st Law The law of inertia The state of motion of an object does not change as long as the net force acting on the object is zero. Objects at rest stay at rest; Objects in motion stay in constant straight-line motion. Unless acted on by an outside force.

6. Forces in action Seat belts work using inertia. In a head-on collision, your body wants to stay in motion. The seat belt keeps you from continuing to travel.