Newton’s First LawNewton’s First Law

By Amanda StevensBy Amanda Stevens

Physical SciencePhysical Science

55thth Period Period

The History of Newton’s Laws The History of Newton’s Laws

Sir Isaac Newton described the Sir Isaac Newton described the relationship between motion and relationship between motion and force in the laws that we now call force in the laws that we now call Newton’s laws of motion.Newton’s laws of motion.

His laws apply to a wide range of His laws apply to a wide range of motion like a caterpillar crawling on a motion like a caterpillar crawling on a leaf, a person riding a bicycle, or a leaf, a person riding a bicycle, or a rocket blasting off into space.rocket blasting off into space.

First LawFirst Law

An object at rest remains at rest and An object at rest remains at rest and an object in motion maintains its an object in motion maintains its velocity unless it experiences an velocity unless it experiences an unbalanced force.unbalanced force.

Objects Tend to Maintain Their Objects Tend to Maintain Their State of Motion.State of Motion.

Inertia-the tendency of an object to Inertia-the tendency of an object to resist being moved or, if the object is resist being moved or, if the object is moving, to resist a change in speed moving, to resist a change in speed or direction until an outside force or direction until an outside force acts on the object.acts on the object.

Inertia Is Related to an Object’s Inertia Is Related to an Object’s MassMass

Matter resists any change in motion. Matter resists any change in motion. An object will remain at rest until An object will remain at rest until something makes it move.something makes it move.

Mass is a measure of inertia. An Mass is a measure of inertia. An object with a small mass has less object with a small mass has less inertia than an object with a large inertia than an object with a large mass.mass.

Seatbelts Provide ProtectionSeatbelts Provide Protection

Because of inertia, you slide toward the Because of inertia, you slide toward the side of a car when it makes a sharp turn. side of a car when it makes a sharp turn.

Inertia is also the reason why cars, planes, Inertia is also the reason why cars, planes, and bicycles cannot come to a complete and bicycles cannot come to a complete stop instantly. stop instantly.

When your car is coming to a stop, your When your car is coming to a stop, your seat belt and the friction between you and seat belt and the friction between you and the seat stop your forward motion.the seat stop your forward motion.

They provide unbalanced rearward forces They provide unbalanced rearward forces needed to bring you to a stop as the car needed to bring you to a stop as the car stops.stops.

That’s why babies are placed in a That’s why babies are placed in a backward-facing car seat. The force backward-facing car seat. The force that is needed to bring the baby to a that is needed to bring the baby to a stop is safely spread out over the stop is safely spread out over the baby’s entire body.baby’s entire body.

SourcesSources

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