MONDAY
3/19
- YOU ARE GOING HOME FROM
SCHOOL YOU TRAVEL 4 KM, YOU
DECIDE TO STOP AT THE MALL
WHICH IS ANOTHER 4 KM, THEN
YOU GRAB DINNER AT TACO
BELL WHICH IS 2 KM AWAY. THE
TRIP TAKES YOU 2 HOURS.
WHAT IS THE AVERAGE SPEED
OF YOUR TRIP?
- 5 KM/H
AGENDA
Do now (2 min)
Notes/videos (10 min)
Class practice (5 min)
Group Practice (8 min)
Independent Practice (10 min)
Closing (5 min)
MARBLE LAB REPORT
DUE TOMORROW
DON’T FORGET YOUR BACKGROUND/INTRO
Lose ten points for every day late
No emailed/flash drive work- Must be printed
TOPIC: FORCES
Write in Questions as we go
WHAT IS FORCE?
A force is simply a push or a pull.
All forces have both direction and strength
Any time there is a change in acceleration this means that
the change was caused by a force.
WHAT IS A FORCE?
All forces act on objects.
Not all forces causes an object to move. For example you are
all sitting on chairs, this exerts a force, but you do not cause
the chair to move by sitting on it.
You also cannot see all forces, like the force of gravity or the
force that attracts two magnets.
PARNER:
TRUE OR FALSE
 1. A force is a push or a pull
 2. You can see all forces
 3. Forces always cause an object to move
NET FORCE
 Usually more than one force is acting on an object.
 The NET FORCE is the combination of all the forces
acting on an object.
BALANCED FORCE
When the forces of an object produce a net force of 0, then the
forces are BALANCED FORCES.
Balanced forces will not create a change in motion of an object.
Some examples of balanced forces are a hat sitting on your head,
a birds nest resting in a tree, or a light bulb hanging from the
ceiling
UNBALANCED
FORCE
 When the net force is ANYTHING other than 0 then the
force is UNBALANCED.
 For example a tug-a-war between is an unbalanced force.
 Unbalanced forces are necessary to move an object.
5 TYPES OF FORCES
Ff = Friction force
FA = Applied Force
Fn = Normal Force
Fg = Gravity
Fair = Air resistance
FRICTION
A soccer ball rolling on the grass
stops because of friction
exerted by the surface as an
object moves across it and
opposes the motion
FRICTION
On a wet or icy surface, there is
less friction, and people slip easily
APPLIED
FORCE
applied by an
object or a
person
NORMAL
FORCE
support force exerted on an
object on any surface; always 90
degrees to the horizontal
NORMAL
Normal Force
FORCE
What are
the 2
forces
acting on
you
RIGHT
NOW?
gravity
gravity
gravity
Air
resistance
a type of frictional force
that acts on objects
moving the air and
opposes the motion
Air
resistance
What two
forces are
at work on
a skydiver?
YOUR NOTES OVER
AND QUIZ YOUR
PARTNER
CLASS PRACTICE
Label the forces that are acting in each situation
A PERSON STANDING
ON THE FLOOR.
A WAGON BEING
PULLED UPHILL.
Fg
Fn
Fa
Ff
A CAR DRIVING
DOWN THE STREET.
A PERSON PUSHING
A WALL.
A FOOTBALL TOSSED
IN THE AIR.
LIBRARY VOICES, 10
MIN, IN GROUPS
1)An airplane flying (3
forces)
Fg, Fa, Fair
4) A ball being tossed
in the air (3 forces)
Fair, Fg, Fa
1)A glass sitting on a
table (2 forces)
Fn, Fg
1)A ball that was
pushed and it rolling
across a table (4
forces)
Fa, Ff, Fg, Fn
5) A rolling chair shoved
and rolling across the
floor (4 forces)
Fa, Ff, Fg, Fn
INDEPENDENT
PRACTICE
SILENT, ALONE
CLOSING
Is the net force on the pencil sharpener BALANCED or
UNBALANCED? How do you know?
ANSWER IN TAG OR RECEIVE ZERO POINTS
DO NOW
3/20
In a game of tug of war like
the one shown above, are the
forces BALANCED or
UNBALANCED? Explain your
answer.
AGENDA- PLACE YOUR LAB
REPORTS DUE TODAY IN ONE PILE
ON YOUR TABLE
Do now
Assign HW
Forces practice
Independent practice
Closing
HOMEWORK DUE
FRIDAY
WITH A PARTNER,
LIBRARY VOICES, AT
YOUR TABLES 20 MIN
Complete the tasks on your paper and answer the questions.
I will collect one per partner group
INDEPENDENT
PRACTICE, 10
MINUTES
SILENT, ALONE
Page 73
CLOSING
What are the forces acting on a ball kicked along a field? Are
they balanced or unbalanced?
ANSWER IN TAG
DO NOW
Choose 2 of the objects at your table.
1. Which has a greater
mass?
2. If you drop them both to
the ground from the same
height, which do you think
will hit the ground first?
DEMONSTRATION (2
MINUTES)
Drop your objects and see which one hits the ground first
DEMONSTRATION
DISCUSSION (2 MINUTES)
1. What happened?
2. Why when I drop a coffee filter and balled filter do they hit
the ground at different times?
AGENDA
Do now
Demonstration
NASA video
Notes
Practice
Closing
IF THERE WAS NO AIR…
IF THERE WAS NO AIR…
PLEASE TAKE OUT A
CORNELL NOTES FOR
QUICK NOTES
Topic: Gravity And Acceleration
TWO OBJECTS WILL FALL
AT THE SAME
RATE.
TWO OBJECTS
WILL FALL
AT THE SAME RATE.
IT IS AIR RESISTANCE
THAT
WILL INFLUENCE THE
IT IS AIR
RESISTANCE
RATEINFLUENCE
AT WHICH AN
THAT WILL
OBJECT
FALLS.
THE RATE
AT WHICH
AN
OBJECT FALLS.
How does gravity affect
how objects fall?
Two objects will fall at the same rate.
What makes some
objects fall slower than
other on Earth?
It is air resistance that will influence the rate at which
an object falls.
LAW OF GRAVITY
“All objects in the universe attract each other
through gravitational force.”
F = m1m2
d2
As the distance
between objects
increases, the
force attracting
them decreases
As the mass of
objects increases,
so does the force
attracting them to
one another
GRAVITY AND
ACCELERATION
On the Earth’s surface
acceleration due to gravity is
9.8 m/s2.
Objects in a vacuum (no air)
will fall at the same rate.
GRAVITY AND
ACCELERATION
Objects of same size and
shape will fall at the same
rate with no air resistance.
Full Water
Bottle
Empty
Water
Bottle
9.8 m/s2
9.8
m/s2
WHAT DOES GRAVITY DO IN
SPACE?
PRACTICE
15 min, in pairs or alone, library voices
CLOSING/ INDEPENDENT
PRACTICE
How does gravity affect acceleration of falling objects on
Earth?
ANSWER IN TAG (COMPLETE SENTENCE) OR RECEIVVE
ZERO POINTS
TRUE OR FALSE?
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
If the earth stopped spinning we would float into space.
There is no gravity on the moon.
NASA have an anti-gravity room where gravity can be
turned off and people can float.
It is possible to shield the force of gravity by using lead
or other materials.
Isaac Newton discovered gravity.
The Philles won the World Series in 1980 and 2008.
You have no mass in space.
There is no gravity in space because you are far from the
earth.
Weight is measured in kilograms.
There is no gravity in space because space is a vacuum.
If we could suck all the air out of the classroom, we
would float around.
ALL FALSE!
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
Only this one is
true!
If the earth stopped spinning we would float into space.
There is no gravity on the moon.
NASA have an anti-gravity room where gravity can be
turned off and people can float.
It is possible to shield the force of gravity by using lead
or other materials.
Isaac Newton discovered gravity.
The Philles won the World Series in 1980 and 2008.
You have no mass in space.
There is no gravity in space because you are far from the
earth.
Weight is measured in kilograms.
There is no gravity in space because space is a vacuum.
If we could suck all the air out of the classroom, we
would float around
GRAVITY
What is gravity?
GRAVITY
Gravity is a force between ALL objects!
Gravity
GRAVITY
Gravity is a very weak force.
The force of gravitational attraction
betweenthese two people (when 1 meter
apart) is only around 0.0000004 Newtons!
GRAVITY
The size of the force depends on the mass of the
objects. The bigger they are, the bigger the force!
Small attractive force
Bigger attractive force
GRAVITY
The size of the force also depends on the distance
between the objects.
GRAVITY
We only really notice the gravitational attraction to
big objects!
Hola! ¿Como estas?
GRAVITY
The force of gravity on something is called its weight.
Because it is a force it is measured in Newtons.
Weight
GRAVITY
On the earth, Ms. B’s weight is around 800 N.
I love science!
800 N
GRAVITY
On the moon, her weight is around 130 N.
Why?
130 N
GRAVITY
In deep space, far away from any planets or stars her weight
is almost zero. (He is weightless). Why?
Cool!
MASS
Mass is a measure of the amount of material an
object is made of. It is measured in kilograms.
MASS
Ms B has a mass of around 50 kg. This means he is
made of 50 kg of blood, bones, hair and poo!
50kg
MASS
On the moon, Ms. B hasn’t changed (she’s still Ms.
B!). That means she still is made of 50 kg of blood, bones,
hair etc!
50kg
GRAVITY
In deep space, Ms. B still hasn’t changed (she’s still
Ms. B !). That means she still is made of 50 kg of blood,
bones, hair etc!
I feel sick!
50kg
MASS AND WEIGHT
Mass is a measure of the amount of material an
object is made of. It is measured in kilograms.
Weight is the force of gravity on an object. It is
measured in Newtons.
CALCULATING
WEIGHT
The force of gravity on one kilogram is called the
gravitational field strength. It s measured in Newtons per
kilogram (N/kg)
CALCULATING
WEIGHT
To calculate the weight of an object you multiply the object’s
mass by the gravitational field strength wherever you are.
Weight (N) = mass (kg) x gravitational field strength
(N/kg)
EXAMPLE
The gravitational field strength on earth is around 10 N/kg.
What is your weight if your mass is 45 kg?
Weight (N) = mass (kg) x gravitational field strength
(N/kg)
Weight (N) = 45 kg
Weight = 450 N
x 10 N/kg