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Monday, March 13th
Entry Task
Do YOU exert a
gravitational force?
Justify your
answer.
Schedule:
• 12.1 notes & questions
• Objective: I can explain
that gravity is a force
exerted by masses
Homework
• 12.1 notes & questions
• Read pages 381-387
carefully
Please have on desk:
• Introduction to Chapter
12 (vocabulary)
What we learned before
• Every action force has an equal
and opposite reaction force
• Newton’s laws are used to
describe the motions of objects
• Mass is the amount of matter an
object contains.
Gravity is a force exerted by
masses.
Gravity is a Universal Force
because it acts between any
things with mass.
Gravity requires 2 things with
mass to be present.
Gravity is a force exerted by masses.
Greater Mass results in greater force
Greater distance results in smaller force.
Force of Gravity Depends On…
• Mass of the objects
– More mass  greater force of
gravity
– If mass is doubled, force of gravity
doubles
• Distance between the objects
– More distance  less force of
gravity
– If distance is doubles, force of
gravity is 1/4th
Earth exerts a downward (action) force on pencil
Pencil exerts an upward (reaction) force on Earth
Net force not
strong
enough to
move earth
(too much
inertia), but
can move the
pencil
Gravity accelerates objects
Acceleration due to
Earth’s gravity is
9.8 m/s2 (1 G)
Free template from
www.brainybetty.com
W=mg
• If an object is dropped on Earth it
accelerates towards it because of the
gravitational pull.
• This acceleration is called g
– g=9.8 m/s²
• Newton’s 2nd law (from Chapter 11)
–
–
–
–
Formula F=ma
Substitute w for F
Substitute g for a
w=mg is the formula for calculating the
weight of an object (it’s a force!) close to
Earth’s surface
Gravity accelerates objects
A thrown object will
hit the ground at the
same time as a
dropped object (If all
other forces are
absent)
Weight and Mass
MASS – The amount of matter
in an object (Does not change
based on surroundings)
WEIGHT – The amount of
gravitational force acting on
an objects (Does change
based on surroundings)
Weight is a measure of the
force of gravity
Because gravitational pull between you
and the moon is weaker, you weigh less
on the moon. REMEMBER…Weight and
mass are different things
Tuesday, March 14th
Entry Task
Gravity is pulling the
moon toward the
center of Earth. Why
doesn’t it crash into
Earth?
Schedule:
• Relating Mass and
Weight activity
Objective:
• I will measure and
graph the relationship
between mass and
weight.
Homework:
• Complete the activity if
not finished in class.
Please have on desk:
• ISN open to 12.1
notes
Happy Pi Day
Wednesday, March 15th
Entry Task
Calculate the weight
of a 50 kg object
on Earth. Write the
formula, show your
work with units
and answer with
units.
Schedule:
• Gravity Review
Objective:
• I can explain the
relationship between
mass, distance, and
gravitational force
Homework:
• Math problems if not
finished in class
Please have on desk:
• Relating mass and weight
activity
Thursday, March 16th
Entry Task
Why is this activity
not safe on the moon,
but is sort of safe on
the earth?
Schedule:
• Friction notes
Objective:
• I can describe how
friction affects motion.
Homework:
• Finish the output page.
Please have on desk:
• ISN, textbook, pencil
Friction Basics
• Draw an example of Friction
being necessary for motion.
• Draw an example of Friction
opposing motion
Friction Basics
• What 3 things determine how
much friction occurs between
two surfaces?
Friction Basics
• What happens to air resistance
when surface area increases?
• How about when speed
increases?
Friction Basics
• The types of surfaces of the objects;
The speed of the object; The weight of
the object
• Surface Area increases = Friction
Increases
• Speed Increases = Friction Increases
As you read the Friction article,
• Highlight important information
• Circle Vocabulary words
• Make annotations
– At least 3 per page
– Thought, feelings, questions, summarize
Friday, March 17th
Entry Task
How can you decrease
the friction between
a dishcloth and a
plate?
Schedule:
• Science Friction
• Bill Nye “Friction”
Objective: I can
demonstrate my
understanding of gravity
and friction.
Homework:
• No homework
Please have on your desk:
• ISN open to mass and
weight worksheet