Unit 11
The Law of Universal Gravitation
Background info required
• Before you learn about Universal Gravitation ..
You need to know where it resides within the
governing forces for our world.
• Also…. You should be able to tell me the unit
of measurement for Force.
• It is a ______________?
• We also say that Weight is a ___________?
FYI
• The next slide is not on your notes, you will
need to write this info on your notes – either
in the side margin or on your own paper.
There are 4 discrete FORCES that
govern the interactions of matter.
They are listed below in order of STRONGEST to WEAKEST.
1. Strong Nuclear Force – responsible for keeping
quarks together inside protons and neutrons
2. Electromagnetism – range is infinite, has + & - charges
that can combine or cancel each other out.
3. Weak Nuclear Force – responsible for radioactive
decay
4. Gravity- range of gravity is unlimited & exist bet. 2
masses & the dist. bet. them.
Gravitation is Universal
• Gravity arises from the warping of
space and time.
• Gravity is a way masses
communicate with each other.
Tangential Velocity Refresher
• What is it ?
• And
• What does it look like?
Hopefully, you were thinking….
• It is Linear
And it looks like
• A straight line coming off a point on the circle.
Space -Time Warp
• Tangential velocity of the Earth allows it to fall
around the sun rather than falling directly into
the sun and crashing into it.
The Law of Univ. Gravitation states..
• Every particle attracts every other particle
with a force that is proportional to the mass of
the particles and inversely proportional to the
square of the distance between them.
There is a constant that is used in
this formula ( G )
• The Universal Constant of Gravitation
• Which is: G = 6.67 x 10-11 N * m2 / kg2
• It is also written with Fg and Fgrav w/ the G
written in a different location.
When solving, it looks like….
Force = (universal constant of gravitation) ( mass 1) Mass 2)
(distance)2
The unit for Force is Newtons.
The proportionalities expressed by Newton's universal law
of gravitation can also be represented graphically.
Go to:
http://www.physicsclassroom.com/Class/circles/u6l3c.cfm
And discuss proportionality info
Problem Solving
• Go to pg. 97 in the Problem Solving Exercises
Physics Workbook.
• Read pg. 97. Then, review example 1, 2, and 3.
• Next, complete Practice Exercises 1, 3, & 5 on
pg. 98 – 100.
Check your work!!
• The answers to # 1, 3, and 5 can be found on
pg. 249.
• You must have work shown for your answers
to receive credit for this activity.