6.1 Newton’s First Law pp. 138-140

NEWTON’S THREE LAWS OF MOTION In his book, Principia, Newton described the three laws of motion. He did not discover all three laws, he explained them in a way that many people could understand

NEWTON’S FIRST LAW OF MOTION This is also known as the Law of Inertia It says : An object in motion will remain in motion at a constant speed and in the same direction unless acted on by an unbalanced force. An object at rest will remain at rest unless acted upon by an unbalanced force.

6.1 Law of inertia Newton’s first law says that objects continue the motion they already have unless they are acted on by a net force. If the net force is zero, an object at rest will stay at rest. If an object is acted upon by unbalanced forces, its motion will change.

6.1 Force changes motion Forces can be used to increase or decrease the speed of an object, or to change the direction an object is moving.

6.1 Law of inertia Inertia is the property of an object that resists changes in motion. Objects with more mass have more inertia and are more resistant to changes in their motion. Which ball has more inertia?

Newtons’s 1st Law and You Don’t let this be you. Wear seat belts. Because of inertia, objects (including you) resist changes in their motion. When the car going 80 km/hour is stopped by the brick wall, your body keeps moving at 80 m/hour.