Download Newton`s 1st Law

Essential Questions
• Who was Sir Isaac Newton?
• What is the first Laws of Motion?
• How do Newton’s Laws affect
motion?
“If I have ever made any valuable discoveries,
it has been owing more to patient attention,
than to any other talent.”
-Sir Isaac Newton
Background
Sir Isaac Newton (1643-1727) an English
scientist and mathematician, is famous for
his discovery of the Three laws of motion.
Today these laws are known as Newton’s
Laws of Motion and describe the motion of
all objects on the scale we experience in our
everyday lives.
While most people know what Newton's
laws say, many people do not always
know what they mean.
1.
2.
If I carefully set this block here, what do you think will happen next? How do you know?
If I decide to give this block a push, what will happen? How do you know?
Newton’s First Law
“An object at rest tends to stay at rest and an object in
motion tends to stay in motion unless acted upon by
an unbalanced force.”
Law of Inertia
1st Law
• Unless acted upon
by an unbalanced
force, this golf ball
would sit on the
tee forever.
1st Law
• Once airborne,
unless acted on by
an unbalanced
force, it would
never stop!
• What unbalanced
force stops it?
It’s a force we sometimes cannot see –
gravity or friction!
Things don’t keep moving forever because
there’s almost always an unbalanced force
acting upon it.
A book sliding across a table slows
down and stops because of the force
of friction.
If you throw a ball upwards it will
eventually slow down and fall
because of the force of gravity.
Let’s explore…
• There are four main types of friction:
• Sliding friction: ice skating
• Rolling friction: bowling
• Fluid friction (air or liquid): air or water resistance
• Static friction: initial friction when moving an object
Inertia
• Can an object move on its own?
• NO!!!!!!!!!!!!!!
• INERTIA is the tendency of an object to remain at
rest if it is resting or stay in motion if it is moving.
• Slide a pencil gently across a table and watch it slide
to a rest position. Which unbalanced force acted upon
it to bring it to a resting position?
• In the absence of that force, what would happen to the
pencil?
Inertia
• The more mass an object has, the more
inertia it has.
• A big truck has more inertia than a car.
This is because it is harder to get a truck
moving and harder to stop it.
There’s more inertia
in the truck than in the car.
Real Life…
• Why do we have bullet proof vests?
• Well, the bullet proof vests slow the bullet down, so that
you aren’t injured. The vests are made from a strong
material that can absorb the force of a bullet, therefore
slowing it down.
More Examples from Real Life…
A soccer ball is sitting at rest. It
takes a force of a kick to change its
motion.
Two teams are playing tug of war. They are both exerting equal force
on the rope in opposite directions. This balanced force results in no
change of motion. Any change in the balance would mean that there
is now an unbalanced force at work!
Let’s explore our own “real life” example…
Newton's 1st Law and You
Seatbelts anyone?
• What happened in the experiment?
• How does it relate to Newton’s 1st law?
• Don’t let this be you. Wear seat belts.
• Because of inertia, objects (including you) resist changes in
their motion. When the car going 80 km/hour is stopped by
the brick wall, your body keeps moving at 80 m/hour.
Let’s Review
A(n) __________ is a push or a pull.
A) motion
B) velocity
C) acceleration
D) force
Let’s Review
Forces that cancel each other are called __________ forces.
• A) neutral
• B) balanced
• C) inactivated
• D) null
Let’s Review
• Newton's first law of motion states that __________.
• A) an object will remain at rest or keep moving with a
constant velocity unless a force acts on it
• B) acceleration is calculated by dividing the force
exerted on an object by the mass of the object
• C) when a force acts on an object, its acceleration is in
the same direction as the force
• D) when a force is applied on an object, there is an equal
force applied by the object in the opposite direction
Let’s Review
__________ is a force that resists motion between two
surfaces.
• A) Resistance
• B) Inertia
• C) Friction
• D) Acceleration
Let’s Review
• __________ measures an object's tendency to resist
changing its motion.
• A) Gravity
• B) Acceleration
• C) Mass
• D) Inertia
Let’s Review
•
A ball is thrown straight up in the air. According to
Newton's first law of motion, what is the reason for the
ball falling back to Earth?
A) A force has acted on it.
B) It is accelerating in the same direction as Earth's
gravitational force on it.
C) The change in the ball's acceleration is proportional to
the force acting on it.
D) The ball exerts a force on the air surrounding it.
Let’s See Newton’s 1st Laws
at Work…
Station 1:
 Pillowcase Trick
Station 2:
 Thump
Station 3:
 Poker Pile
Station 4:
 Friction in Everyday Life
Station 5:
 Explaining Newton’s Laws
Station 6:
 Taking notes