Newtons Laws' History and First Law

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Newton's Laws of Motion

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The History of the Laws of Motion

Aristotle, a Greek philosopher, and Galileo Galilei, an Italian

astronomer, may have been two of the first scientists to try to explain

gravity and motion.

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In the late 1600s, Sir Isaac Newton
used Galileo's ideas to create three
basic laws of motion.

The History of the Laws of Motion

Sir Isaac Newton contributed to
advances in physics, mathematics,
and astronomy.

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Laws of Motion

Newton may be one of the
greatest scientists in
history. The three laws of
motion he created are
three of the most used
natural laws in science.

These laws help us to
make sense of the world
around us.

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Newton was inspired by the apple falling from the tree and
asked himself if gravity might also be the force holding the

moon in orbit.

Newton found that gravity plays a role in other orbital motions

as well!

Laws of Motion

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Newton's First Law of Motion

The first law of motion tells us that an object at rest stays at rest,
and an object moving at a constant velocity will continue moving at
a constant velocity, unless acted on by an unbalanced force.

On Earth, gravity and
friction are two of the
unbalanced forces that
frequently change an
object's motion.

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The first law of motion is sometimes referred to as the law of inertia.

Newton's First Law of Motion

Inertia is the tendency of an object to resist a change in motion.

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The First Law of Motion

The first law basically tells us that motion will not change without
a net force. So, if an object stops moving or starts moving, you

know there is a net force.

If there is a net force, then the forces are
unbalanced. As you know, unbalanced
forces cause changes in motion!

Apply Newton's First Law of Motion to
the baseball player sliding into second
base. What are some forces acting on
him?

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Application of The First Law of Motion

Have you ever wished that you could just tell
your clothing to move itself to the closet?

Unfortunately, we know that objects don't move on their own. An
unbalanced force is required to make an object change its state
of motion.

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Imagine you need to move a few pieces of furniture in your
room. Would you rather move your dresser with everything in
it or your dresser when its empty?

Application of The First Law of Motion

Be sure to use the term
inertia in your answer.

Based on your answer, how are inertia and mass of an
object related?

Multiple Choice

Inertia is the resistance of an object to change in
its state of motion.

• True

• False

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34 Inertia is the resistance of an object to change in
its state of motion.

True

False

Multiple Choice

The law of inertia applies to___________.

• moving objects

• nonmoving objects

• both moving and nonmoving objects

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Which has more Inertia?

A Tennis Ball or a Bowling

Ball?

Why?

The bowling ball will
have more inertia because

the more mass an object has
the more it resists a change in motion.
This applies to heavier objects regardless of
whether they are moving or at rest!

Multiple Choice

Which object has the greatest inertia?

• car

• Moving Freight Train

• tennis ball

Multiple Choice

Which object has the greatest inertia?

• tennis ball at rest

• tennis ball in motion

• both have the same inertia

Multiple Choice

A ball will accelerate when it is acted on by 2
equal forces pointing in opposite directions.

• True

• Falsee

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39 A ball will accelerate when it is acted on by 2
equal forces pointing in opposite directions.

True

False

if the forces are acting in opposite directions, then
they are acting towards each other and the ball
is balanced