# Force and Newtonâ€™s Laws of Motion

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```							Force and Newton’s Laws of
Motion
BY: BRIANNA SHIELDS
DO NOW
 1. If a foam block and a brick are
dropped from the roof of the school,
which one will hit the ground first?
 2. Where on Earth could you go to
weigh the most?
 3. When a pendulum is allowed to
freely swing back and forth it eventually
slows down. Why?
GOAL
 To define force and give examples of it

 To apply Newton’s Laws of Motion
Physics Current Event
 Read the article “Fantastic Physics”
from the Current Science magazine
 Use the response starters on your ELA
bookmark to write 3 RESPONSES to
the article
 Force    1. Any push or pull
 2. Can do one of the following:
– Balance each other out
– Overpower one another
– Work together
 Wind blowing on a flag
 Push

 A magnet attracting metal
 Pull
 Jet engine moving a plane
 Push

 Moon causing the tides
 Pull
 Nuclear explosion
 Push

 Proton and electron attracting
 Pull
 Blowing up a balloon
 Push

 Tug of war
 Pull
 Gravity
 Pull

 Closing a door
 Push or pull
Defining Force
 2 forces in
the same
direction get
together
Example
 Suppose you couldn't pull a wagon of rocks
yourself, so a friend started pulling on it with you-
the pulling forces of you and your friend would be
going in the same direction so you add them
together
Defining Force
 2 forces - one
going one way,
one going the
other are
subtracted from
one another
-   =

 Object will move
in the direction
that the larger
force is pointed
towards
Example
 If a girl pulls a wagon against you in the opposite
direction, the forces would combine by
subtraction- The wagon would move in the
direction of the greater force

Overall Mvmt
Defining Force
 Equal but
opposite
forces cancel
eachother        O
out
Example
 If a girl pulls a wagon against you in the opposite
direction, the forces would combine by
subtraction- The wagon would move in the
direction of the greater force

No movement
Try the Force Examples on your
handout
 Draw a picture of each scenario
 Label the forces with vectors (arrows) and
amounts of force
 Calculate the total force
 Show the final direction of movement (if
there is any)
 When your group is finished, raise your
 Newton’s    An object in motion will stay in
First Law     motion, an object at rest will stay at
of Motion     rest, unless acted on by a force
 Newton’s    A force accelerates in the direction
Second        of the force & is related to the
Law of        object’s mass
Motion       F= ma
 Newton’s    For every action, there is an equal
Third Law     but opposite reaction (forces come
of Motion     in pairs)
Which Law of Motion?
 When riding in a car that stops
forward.
Which Law of Motion?
 The force of friction acts against an
object’s motion.
Which Law of Motion?
 When you’re driving fast on a straight
road and then go around a sharp curve,
why does everyone in the car bump into
eachother or the doors and walls?
Which Law of Motion?
 You are pushing a cart in the grocery
store. The more force you apply (the
harder you push) the greater the cart
accelerates. A full cart requires a
greater force to accelerate.
Which Law of Motion?
Which Law of Motion?
Which Law of Motion?
 The “kickback” of a gun on your
shoulder while shooting it
Which Law of Motion?
 As you walk, your feet push on the floor
and the floor pushes back on you
Which Law of Motion?
 Pulling a tablecloth out from beneath
dishes without upsetting the dishes
Which Law of Motion?
Which Law of Motion?
 While stepping off a boat, the boat
pushes away from you.
Which Law of Motion?
 If you are standing on a bus that
suddenly moves forward, you are
thrown off balance. Why?
Which Law of Motion?
 Why does a small car get better gas
mileage?
Which Law of Motion?
 How much force is needed to accelerate
a 1400 kg car 2 m/s/s?
Which Law of Motion?
Which Law of Motion?
 Push on a desk- even if it doesn’t move
you should have a mark on you hand.
The harder you push on it, the harder it
pushes back
Which Law of Motion?
 Holding a bucket- you arm is holding it
up, at the same time that gravity is
pulling it down
Assessment
 Use the formula F= ma to solve the
following problem: A go-cart has a
140kg person in it. How much force
would be required to accelerate the go-
cart at 3m/s/s?
Assessment
 In your lab groups, come up with one of
your own examples for each of the three
laws of motion:
– Newton’s 1st law of motion
– Newton’s 2nd law of motion
– Newton’s 3rd law of motion

```