# Motion and Historical Figures. Keywords Aristotle Galileo Sir Isaac Newton ForceInertia.

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Motion and Historical Figures

Keywords Aristotle Galileo Sir Isaac Newton ForceInertia

The Greek philosopher Aristotle (380 BC) He came up with “natural motion” "What goes up...must come down."

2000 years later - Italian physicist Galileo: Galileo wondered why things stopped moving. He came up with a invisible force called friction. "without friction, an object in motion would continue to move forever." friction

Sir Isaac Newton

1687 - Isaac Newton rewrote the laws of motion. Most famous for his ideas on gravity, and the Three laws of motion. FIRST LAW – called the Law of Inertia: "An object at rest tends to stay at rest and an object in motion tends to stay in motion; unless acted upon by an unbalanced force."

"keep on doing what they're doing" How well an object resists changes in its state of motion depends how heavy it is (it’s mass). The more mass, the more inertia - the more it will resist changes in its state of motion. Inertia: resistance an object has to changes in its state of motion.

The truck has most mass and so the most inertia. It would also be the hardest to STOP moving. It is the hardest to START moving.

Force: a vector with the units - Newton (N). "An object at rest tends to stay at rest and an object in motion tends to stay in motion; A force is a push or a pull unless acted upon by an unbalanced force." F

When all forces acting on an object are, the motion of the object will NOT change. Therefore - Unbalanced forces will cause the acceleration of an object (non-uniform motion). balanced Unbalanced

The same principle applies to all occupants and objects in a vehicle. Thrown from a bike or through the windshield.

Use your experiences to explain whiplash injury in an accident - using the term inertia.

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