Newton’s First Law of Motion

Let’s review what a FORCE is: A Push or a Pull that causes an object to move

Balanced forces – all forces acting on an object are equal There is NO CHANGE IN MOTION Net force = 0N Unbalanced forces – one or more forces acting on an object are stronger than others There is CHANGE IN MOTION (acceleration) Net force ≠ 0N (object feels like it is being pushed or pulled)

Newton’s 1st Law (also known as the law of inertia) Objects do not change their motion unless an unbalanced force acts on them What does this mean? An object at rest will: stay at rest A object in motion will: stay in motion

Stopping Motion QUESTION: Why won’t a moving object continue moving forever? Example: pushing your desk across the floor ANSWER: There has to be an unbalanced force that acts to stop its motion (FRICTION!) This can make it hard to observe Newton’s 1st Law on everyday objects

Objects at Rest Objects at rest tend to stay at rest unless acted upon by a force. Inertia = tendency of an object to keep doing whatever it’s already doing.

Which vehicle has more inertia? Mass & Inertia Mass is the amount of matter in an object. The more MASS an object has, the more INERTIA the object has. Bigger objects are harder to start & stop Example: bowling ball vs soccer ball Which vehicle has more inertia?

Check for understanding: Describe what is happening in the animation according to Newton’s 1st Law.