Transcript Newton

Newton’s Laws of Motion
Instructions: During this PowerPoint, you will be applying the
information presented in your journal. Be sure to number the
questions and write in complete sentences when needed. Be
sure to add more notes to yours when you learn something new.
1. Your Turn: In your journal, write at least 3 things you already
know about Sir Isaac Newton and/or his Laws of Motion.
Sir Isaac Newton
• Born January 4, 1643
in England
• As a young student,
Newton didn’t do well
in school.
• He worked hard and
continued his
education.
• Later in life, Newton
contributed ideas that
became law in the
worlds of science and
math.
REVIEW
First we need to define the
word FORCE:
• The cause of motion (what
causes objects to move)
• Two types of forces
– Pushes
– Pulls
REVIEW
Forces are measured in
Newtons
• SI unit of force
• Symbol: N
• Measured by using a spring scale
REVIEW
Forces may be balanced or
unbalanced
• Balanced forces – all forces acting
on an object are equal
– There is NO MOTION
• Unbalanced forces – one or more
forces acting on an object are
stronger than others
– There is MOTION
• A NET FORCE
Newton’s Laws
• First Law – Inertia
• Second Law – Acceleration,
Force & Mass
• Third Law – Action-Reaction
Newton’s Law of Inertia
• “An object at rest tends to stay at rest and
an object in motion tends to stay in motion
with the same speed and in the same
direction unless acted upon an outside
force.”
2. Your Turn: In your journal, draw 2
pictures (cannot use a soccer ball) that
represent this law.
First Law
• Inertia
– An object at rest
[not moving]
remains at rest
unless acted on by
a force [push or
pull].
– An object in
motion remains in
motion unless
acted on by a force
[push or pull].
First Law
• Inertia & Mass
– Mass is the amount of matter in an
object.
– The more MASS an object has, the
more INERTIA the object has.
– Bigger objects are harder to start &
stop.
http://toons.artie.com
First Law
Example of Newton’s First Law in
Action:
http://vimeo.com/2727482
Newton’s Law of Force and
Acceleration
3. Your Turn: In your journal, solve the following
problem –
A student starts a food fight by throwing a 0.5 kg
burrito at some girl he likes. He throws it pretty
hard so it accelerates at 3 m/s2. How much
force did this take?
Second Law
• Acceleration & Mass Definitions
– Acceleration is a change in velocity
[speed or direction].
– Mass is the amount of matter in an
object.
Second Law
• Acceleration & Force
– The more force placed on an object,
the more it will accelerate [change its
motion].
• Acceleration & Mass
– The more mass [or inertia] an object
has, the more force it takes to
accelerate the object.
Second Law
Force = Mass x Acceleration
Example: A 25 g object with an
acceleration of 4 m/s2 will have a
force of ______ Newtons.
Second Law
Force = Mass x Acceleration
Example: A 25 g object with an
acceleration of 4 m/s2 will have a
force of 100 Newtons.
25 x 4 = 100
Second Law
Force = Mass x Acceleration
Falling objects have acceleration due
to gravity which is 9.8 m/s2
For example…
Third Law
• Action – Reaction
– Forces are always produced in pairs
with opposite directions & equal
strengths.
– For every force there is an equal and
opposite force.
Newton’s Law of ActionReaction
• "For every action, there is an equal and
opposite reaction."
Reaction
Action
4. Your Turn: In your journal, explain this law in your own
words, including 1 example.
Third Law
• Action – Reaction
– Action – Reaction Forces act on
different objects…
• When you kick a soccer ball, you exert a
force on the ball and the ball exerts a force
on you. The harder you kick the bigger the
force on you (kicking REALLY hard might
hurt.)
Third Law
The truck is in motion. What is the force
that causes it to stop?
The push of the stopped car.
The car is at rest. What is the force that
causes it to move?
The push of the truck.
What about the ladder on top of the truck?
The ladder is in motion because the truck is in
motion.
When the truck stops, the ladder stays in motion.
The truck is stopped by the force of the car, but the
ladder is not.
What force stops the ladder?
Gravity.
The truck is in motion, the car is at rest. How do
each of these vehicles accelerate?
The truck stops moving. The car starts moving.
Which one will be the hardest to accelerate?
The truck because it has the most mass.
Why does the car move [accelerate] when it is hit
by the truck?
The heavy and moving truck has more force than
the small, at rest car.
Why does the truck stop moving when it hits the
car?
The force of the car pushing back on the truck,
plus the force of friction between the massive truck
and the road slow down, the stop the truck.
The truck hits the car. An action force stops the
truck.
What is the equal and opposite reaction force?
The force that pushes the car forward.
DO NOW – 5 Minutes
November 11-12, 2010
Page 76
Write Newton’s 3 Laws of Motion in your own
words.
Newton’s 1st Law of Motion says ________
______________________________________.
Newton’s 2nd Law of Motion says ________
______________________________________.
Newton’s 3rd Law of Motion says ________
______________________________________.
EXIT TICKET
November 11 - 12, 2010
How is each of Newton’s Laws represented in the
picture above?
Newton’s Laws Foldable
Create a foldable that includes:
•
The official law
•
The law in your own words
•
A picture or illustration to represent the law
•
A real-world example of the law
•
Important vocabulary or math formulas that
go with the law
for each of Newton’s 3 Laws of Motion