newton’s laws of motion 1. your turn: in your journal, write at least 3 things you already know...
TRANSCRIPT
Newton’s Laws of Motion
1. Your Turn: In your journal, write at least 3 things you already know about Sir Isaac Newton and/or his 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.
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.
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
REVIEW
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
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 muchforce 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 Action-Reaction
• "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.
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 ________ ______________________________________.
DO NOW – 5 Minutes
November 11 - 12, 2010EXIT TICKET
How is each of Newton’s Laws represented in the picture above?
Newton’s Laws FoldableCreate 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