Newtons Laws of Motion Click mouse to advance to the next slide

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Newtons Laws of MotionClick mouse to advance to
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Sir Isaac Newton
The Father of Modern Science

• Sir Isaac Newton, (1642-1727), is probably known
  by most grade school students and people as the
  man who discovered gravity. According to the
  well-known story, while sitting under an apple
  tree in his orchard an apple fell and struck
  Newton on the head. As folklore has that this
  event caused the discovery of gravity. What
  actually happened as the result of the apple
  falling on Newton head is that it caused him to
  wonder if same force that governed the motion of
  the Moon also governed the apple. So, He
  calculated the force needed to hold the Moon in
  its orbit, and then compared it with the force
  pulling an object to the ground, and found out
  that it was the same force.

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Sir Isaac Newton
The Father of Modern Science

• Sir Isaac Newton, (1642-1727), Newton has
  been regarded for almost 300 years as the
  founding of modern physical science, and is known
  as one of the foremost scientific intellects of
  all time. But Newton did not only studied
  science, he studied mathematics, astronomy,
  history, and religion.
• Newton loved to think about things and why
  things happened. He thought about the ways
  scholars of his time explained how things
  interacted with nature, and began to come up with
  his own ideas. Being a mathematician Newton knew
  that math had a definite answer and that using
  mathematics he could find the answers to
  problems. So, Newton use mathematics and
  converted these ideas into mathematical problems.
  Using math Newton found ways to prove his way of
  thinking correct and by using mathematics changed
  the way scholars viewed science.

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Sir Isaac Newton
The Father of Modern Science

• One idea that Newton proceeded to change was
  the way scholars of his day viewed how objects
  move. When scholars studied things they used
  what they could observe and logic to solve
  problems. For example before Newton, scholars
  believed that all objects were at a constant
  state of rest. In order to move an object a
  force was needed to move an object, and when the
  force stopped the object would return to the
  state of rest. It was also thought that a
  constant force was needed to keep the object
  moving. This was what scholar observed on Earth.
  But Newton had a different idea. Newton did not
  only think about what happens to objects on Earth
  but also in space. Newton believed that what
  happens on the earth is what happens throughout
  the universe. So when the when Newtons apple
  incident happened Newton compared the apple to
  the moon.
• It is from this incident that Newton came up
  with his Laws of Motion.

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Newtons First Law of Motion

• Newton agreed with the belief of his time
  that if an object was at rest it would stay at
  rest. And that an object at rest needed a force
  to make it move. But Newton did not agree with
  the concept that a constant force was needed to
  keep an object I motion.
• Newton had problems with the idea that a
  constant force was needed to keep an object in
  motion. Being an astronomer Newton knew that the
  moon was in motion around the Earth, and that the
  Earth and other planets were in motion around the
  sun. So if a constant force is needed to keep an
  object in motion where was the force coming from
  that kept the moon moving around the Earth, and
  the Earth around the Sun.

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Newtons First Law of Motion

• If you remember Newtons apple incident,
  Newton related the falling of the apple to the
  motion of the moon around the Earth.
• Newton believed that there was a relationship
  between the motion of the apple falling and the
  moons orbit.
• The relationship Newton decided was gravity.
  The apple falls to the ground because gravity
  pulls it to the ground. Gravity tries to pull
  the moon to the ground but does not. Why? The
  moon is in motion. And the motion of the moon is
  stronger than the pull of the Earths gravity.
  The moon does not fly away from the Earth because
  the pull of the Earths gravity is strong enough
  to keep it from flying off into space.

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Newtons First Law of Motion

• Newton used mathematics to calculate his
  idea, and his mathematics proved correct.
• What scholars of Newtons day did not take into
  account were gravity and friction, that we
  learned about earlier in this lesson.
• In space there is no friction. Therefore
  nothing to slow the motion of an object. Hence
  an object in space will stay in motion.
• Newton also proved that all objects have gravity
  and the more mass an object has the stronger the
  effect of gravity it has.

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Newtons First Law of Motion
Find OUt

• 1. What are two different ways that an object
  can show inertia?
• 2. What two forces combine to stop objects in
  motion?
• 3. Why could you call the First Law of Motion
  the Law of Inertia?

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Vocabulary

• Inertia The tendency of an object to resist a
  change in motion.
• Force A Push or a Pull.
• Gravity A force of attraction that exists
  between any two objects
• Friction A force between surfaces that resist
  the motion of one surface past another surface.

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Inertia
Inertia The tendency of an object to resist a
change in motion
Or You could Say

• An object at rest tends to stay at rest and
• An object in motion tends to stay in motion

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How can an object show inertia?
An object that does not appear to be moving is
said to be at rest.
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How can an object show inertia?
An object that appears to be moving is said to be
in motion.
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How can an object show inertia?
An object can show inertia by.
not moving being at rest
by moving being in motion
or
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What is needed to change an objects inertia?
What is needed to make a golf ball sitting on
top of a tee to start moving down the fairway.
A force would be needed to start the golf ball
moving down the fairway.

• Force A Push or a Pull

(The force must be greater than the inertia of
the ball)
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How does a golf ball show inertia while sitting
on a tee?
The golf ball exhibits inertia while sitting on
the tee. The golf ball will stay on the tee
until a force greater than the force keeping the
golf ball on the tee acts on the golf ball and
changes its motion.
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After receiving a force how does the golf ball
show inertia?
When the golf ball is hit by a golf club, a force
is applied that is stronger than the inertia of
the ball sitting on the tee. The force causes
the golf ball to fly down the fairway.
The golf ball will continue to soar down the
fairway until a force stronger than the inertia
of the golf ball in motion stops the golf ball.
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What forces combine to Change an objects inertia
when an object is in motion?

• After receiving a force the golf ball begin to
  soar.

What force brings the golf ball down to the
ground?
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What force brings the golf ball down to the
ground?
Gravity A force of attraction that exists
between any two objects
Gravity on earth pulls all object towards the
center of the earth. All object are being pull to
the earths center. The closer you are to the
center of the Earth the stronger the effects of
gravity.
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Gravity A force of attraction that exists
between any two objects
When a force is applied to the golf ball, the
force must be stronger than the inertia (force of
gravity) that held the ball to the tee. The ball
will go into motion (again showing inertia).
Gravity continued to work against the golf ball
and pulls it to the ground, until the inertia of
the Earths gravity becomes stronger than the
inertia of the golf ball in motion.
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What forces combine to Change an objects inertia
when an object is in motion?
Gravity Pulls the ball to the ground
As gravity pulls the golf ball down to the
ground, the golf ball continues to roll. The
inertia of golf ball is still strong enough to
continue in motion.
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What force causes the Golf ball, rolling down the
fairway, to stop rolling?
As the golf ball rolls against the ground another
force acts against the ball, what is that force?
Friction A force between surfaces that resist
the motion of one surface past another surface

• Friction between the ball and the ground slow the
  motion of the ball.

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Friction A force between surfaces that resist
the motion of one surface past another surface
As soon as the golf ball lands on the ground
another force begins to act on the ball.
Friction is the force between surfaces that
resist the motion of one surface past another
surface. Friction work to slow the motion of
objects. There is friction between the surface
of the golf ball and the ground.
Gravity also continues to pull the ball to the
ground increasing the effects of friction.
Friction and gravity will work against the
inertia of the golf ball and cause it to stop.
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Newtons First Law of Motion
Newtons First Law of Motion

• 1. Objects that are at rest tend to stay at rest
  unless a greater force acts on them.
• 2. Objects in motion will continue in motion
  unless a greater force acts on them.

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How does Newtons First Law of Motion compare to
Inertia?

• Newtons First Law of Motion
• Objects that are at rest tend to stay at rest
  unless a greater force acts on them.
• Objects in motion will continue in motion
  unless a greater force acts on them

• Inertia
• The tendency of an object to resist a change in
  motion
• An object at rest tends to stay at rest.
• An object in motion tends to stay in motion.

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How does Newtons First Law of Motion compare to
Inertia?

• Newtons First Law of Motion
• Objects that are at rest tend to stay at rest
  unless a greater force acts on them.
• Objects in motion will continue in motion unless
  a greater force acts on them

• InertiaThe tendency of an object to resist a
  change in motion
• An object at rest tends to stay at rest.
• An object in motion tends to stay in motion.

Because Newtons first law of motion and the
definition of inertia say the same thing you
could say that Newtons first law of motion is
the law of inertia. Or you could say that
inertia is Newtons first law of motion
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Newtons First Law of Motion
Find Out

• 1. What are two different ways that an object
  can show inertia?
• 2. What two forces combine to stop objects in
  motion?
• 3. Why could you call the First Law of Motion
  the Law of Inertia?