I. Newton's First Law DEFINITION An object at rest will remain
at rest and an object in motion will remain in motion until acted
on by an outside force!
Slide 3
I. Newton's First Law Examples EXAMPLE If your book is sitting
at rest on your desk it will remain at rest until an outside force
(like a push from you) acts on it If you are riding your bike you
will remain in motion until acted on by an outside force (like
friction). EXAMPLE
Slide 4
I. Newton's First Law Examples EXAMPLE B lood rushes from your
head to your feet while quickly stopping when riding on a
descending elevator.
Slide 5
I. Newton's First Law Examples EXAMPLE The head of a hammer can
be tightened onto the wooden handle by banging the bottom of the
handle against a hard surface.
Slide 6
I. Newton's First Law Examples EXAMPLE To dislodge ketchup from
the bottom of a ketchup bottle, it is often turned upside down and,
thrusted downward at high speeds and then abruptly halted.
Slide 7
I. Newton's First Law Examples Video Clips Newton's First and
Second laws, in Latin, from the original 1687 edition of the
Principia Mathematica.
Slide 8
Your Turn... You have TWO minutes to write three of your own
examples of Newton's First Law of motion in your Science
Notebook
Slide 9
Let's review... The law of inertia states that an object
_____________. A.) will continue moving in a straight line unless
an outside force acts on it. B.) that is NOT moving will not move
unless a force acts on it C.) will continue moving at the same
velocity unless an outside force acts on it D.) all of the
above
Slide 10
Let's review... Th e law of inertia applies to __________. A.)
both moving and nonmoving objects B.) moving objects C.) objects at
rest
Slide 11
Let's review... Swing a weight on a string around your head in
a circular motion. If the string breaks, the weight will most
likely A.) continue to follow a circular path B.) follow a
straight-line path
Slide 12
Let's review... A card can be "flicked" from under a penny and
fly across the room, but the coin wants to remain in its place
(momentarily), the coin is said to have ___________.
Slide 13
II. Newton's Second Law DEFINITION The net force on an object
is equal to the power of its acceleration and its mass Force = Mass
x Acceleration
Slide 14
So... Newton's Second Law of Motion and it only takes a small
force to accelerate an object with a smaller mass. It takes a great
force to accelerate an object with a large mass, accelerate- change
speed or direction The force required to accelerate an object with
a large mass is greater than the force required to accelerate an
object with a smaller mass! Large Force Small Force
Slide 15
II. Newton's Second Law FORMULA A force is a push or a pull. To
calculate force, we use the following formula: F = ma where F =
force in newtons where m = mass in kg where a = acceleration in
m/sec 2
Slide 16
How do rubber bullets work?
Slide 17
II. Newton's Second Law Practice Problem #1 With what force
will a car hit a tree if the car has a mass of 3,000 kg & it is
accelerating at a rate of 2 m/s 2 ? Pull F = (3,000 kg) (2 m/s 2 )
F = 6,000 kg m/s 2 F = 6,000 N ANSWER
Slide 18
A 10 kg bowling ball would require what force to accelerate it
down an alleyway at a rate of 3 m/s 2 ? Pull ANSWER: F = (10 kg) (3
m/s 2 ) F = 30 kg m/s 2 F = 30 N Problem #2 using formula F =
ma
Slide 19
Problem # 3 using formula a = F/m What is the acceleration of a
softball if it has a mass of 0.50 kg & hits the catcher's glove
with a force of 25 newtons? Pull a = Fa = 25 N m 0.50 kg a = 50 m/s
2 ANSWER
Slide 20
Problem # 4 using formula F = ma What is the mass of a truck if
it is accelerating at a rate of 5 m/s 2 & hits a parked car
with a force of 14,000 newtons? Pull m = Fm = 14,000 N a 5 m/s 2 m
= 2,800 kg ANSWER
Slide 21
Slide 22
Slide 23
Slide 24
III. Newton's Third Law DEFINITION Common expression of 3 rd
Law is, To every action theres an equal and opposite reaction
Slide 25
So... Newton's Third Law of Motion If a hammer exerts a force
on a nail (action) then the nail exerts an equal and opposite force
back on the hammer (reaction), causing the hammer to suddenly stop.
When a rocket launches as the fuel burns it emits exhaust out the
bottom of the rocket (action) and then the rocket is pushed in the
up in the opposite direction (reaction). For every action there is
an equal and opposite reaction!
Slide 26
III. Newton's Third Law Demo Desk and Rolling Chair Flash
Slide 27
ACTION Reaction
Slide 28
III. Newton's Third Law Newton's Laws
Slide 29
II. Newton's Third Law
Slide 30
3 3 2 2 2 1 1 1 In the boxes above you will read several
examples of motion. Decide which of Newton's three Laws of Motion
is described in each box. Click on the box and the answer will be
revealed.