Chapter 4 - Laws of MotionChapter 4 - Laws of MotionNotes 4.1a – Newton’s 1st Law

Define Newton’s First Law of Motion.Explain how inertia and mass are related.Define Newton’s Second Law of Motion.Apply Newton’s Second Law of Motion to real life situations.Solve calculation problems using Newton’s Second Law of Motion.

Isaac NewtonIsaac Newton

1642-1727British ScientistPublished 3 rules in 1687 to explain how forces and motion are relatedRules apply to motion of all everyday objects as well as planets, stars and galaxies

That’s why we call it Universal Gravitation

Newton’s first law of motionNewton’s first law of motion

States that the motion of an object changes only if an unbalanced force acts on the object

If forces are balanced, object doesn’t change its motionOnly unbalanced forces change velocity

InertiaInertia

Tendency of an object to resist a change in its motion1st Law = LAW OF INERTIA

Inertia & massInertia & mass

Inertia varies with massMass is a quantity which depends solely on inertia

More inertia = more massA more massive object has a greater tendency to resist changes in its state of motion

Inertia explains what happens in a car crashCar and your body are moving at the same speedBrakes slow and stop car

Seat belts slow and stop your bodySeat belts loosen slightly to decrease the force acting on your body and increase the time it takes to slow your body (GOOD THING)

NewtonNewton’’s 2s 2ndnd Law Law

Describes how the forces exerted on an object, are related to its mass, and its acceleration.

Newton’s second law of motionNewton’s second law of motion

States that the acceleration of an object is in the same direction as the net force on the object, and that the acceleration can be calculated from the following equation:

Calculating Net ForceCalculating Net Force

Newton’s second law also can be used to calculate the net force if mass and acceleration are known

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