Student Learning Objectives
Students will be able to explain mass of objects with
reference to a basic atomic structure
Students will be able to differentiate between mass and
weight
Students will be able to calculate weight using the
formula
Force = mass x acceleration due to gravity
Students will use the computational tool, Microsoft Excel,
to solve for weights on different planets and graphically
analyze the effects of gravity on weight
Help the kids with their discussion.
Which will get to the ground first in free
fall, the elephant or the feather?
Obviously, it’s
the ……
What is free fall?
Free fall means
air does not
affect the
feather
WHAT IS GRAVITY ?
• A force of attraction between any two masses
• It is not only an attraction between an object and the earth
• It is an attraction between all masses in the universe
GRAVITY
• The more mass an object has
the more gravitational force.
• The sun’s gravity keeps the
earth in its orbit
• The Moon's gravity pulls on
the Earth and makes the tides
rise and fall every day
• Masses on the earth accelerate due to the force of gravity
• Who knows the acceleration due to gravity on the earth?
http://phet.colorado.edu/en/simulation/gravity-and-orbits
MASS
• The amount of matter or “stuff” an object contains
• This matter or “stuff” is atoms, the small particles everything
in the universe is made of
• Atoms contain:
Nucleus – Protons and Neutrons
Electrons
MASS
• What is the unit of measurement
of mass?
• The more matter an object
contains the greater its mass
• An object’s mass stays the same
wherever it is
WEIGHT
• The force on the object due to gravity
• Weight is a force
•
Force = Mass x Acceleration due to gravity
• Weight changes based on
acceleration due to gravity
• The unit of weight is Newton
(N), named after the
scientist Isaac Newton
http://www.youtube.com/watch?v=SegMt7sa42E
ACTIVITY 2 – Weight on Planets
Materials List: pencil,
netbook,
294
???
Tommy has a weight of 294 N
on earth.
Find Tommy’s weight (force)
on the moon, and the other
planets.
ACTIVITY 2 – Weight on Planets
294
???
Find Tommy’s weight on the
other planets
We must first find Tommy’s
mass because it will stay the
same everywhere
Mass = Force ÷ acceleration due to gravity
=
÷
=
kg
Force = mass x acceleration due to gravity
=
X
=
N
Conclusion
A greater acceleration due to
gravity cause a greater
weight.
294
???
A smaller acceleration due to
gravity cause a smaller
weight.
Conclusion
If all objects have the same
acceleration on earth, once
there is no resistance from air
they will fall at the same rate.