Inertia: “The property of objects to resist changes in motion.”

The greater the mass the harder it is to move. And... the harder it is to stop moving. The greater the mass the harder it is to move. And... the harder it is to stop moving.

Lower mass objects are easier to move...and to stop moving.

 A force is a push or pull of one object on another  Its S.I unit is newton (N). phsc001, yanbu university college6

Gravity (weight) - earth’s pull on objects - always downward phsc001, yanbu university college 9

10 Newton's First Law of Motion: Newton’s first law of motion, usually called ‘LAW OF INERTIA’ It is the restatement of Galileo’s Idea. “Every object continues in a state of rest or of uniform speed in straight line unless acted on by a non-zero force.”

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In briefest form, where a is acceleration, F is net force, and m is mass: 13

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Newton’s Third Law of Motion: “ Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.” We can call one force the ‘action force’, and the other the ‘reaction force’. we can express Newton's third law in the following form: “To every action there is always an opposed equal reaction.” 16

Mass is a measure of how much matter an object has. Weight is a measure of how strongly gravity pulls on that matter Mass is scalar quantityWeight is a vector quantity The unit of mass is kg The unit of weight is Newton (N) Mass does not change on different places. Weight changes on different places.

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