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# Four Fundamental Forces of the Universe

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## Shanna Shaked

on 16 November 2013

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#### Transcript of Four Fundamental Forces of the Universe

EXAMPLES
electricity for television, ipod, etc.
compass
Why we don't fall through everything!
our body's electrons repeal electrons in other object
Four fundamental forces
govern
every single interaction
in the universe!

photo credit Nasa / Goddard Space Flight Center / Reto Stöckli
WHAT IS IT? Attractive force between all particles with mass (never repels)
Gravity
Theories that postulate the unification of the strong, weak, and electromagnetic forces are called Grand Unified Theories (often known by the acronym GUTs).

Theories that add gravity to the mix and try to unify all four fundamental forces into a single force are called Superunified Theories. The theory that describes the unified electromagnetic and weak interactions is called the Standard Electroweak Theory, or sometimes just the Standard Model.
Uniting theories
The Four Forces that Shape Our Universe!

`
1. Create an image with
at least one example or use of each of the four forces
. This image can be drawn, or done on a computer, or a collage. Label the examples with letters on the image.

You will hand in your image at the end of the week.

2. Identify the forces in the images of the other students. (due next week)

To make things easier, you will work in groups, so go to the corner with your number on it and start brainstorming ideas for images.
Homework
A force is a PUSH or PULL
on one object by another object
causing a change in:
direction
speed, or
shape

What is a force?
No gravity in hypothetical place with no mass anywhere.
Everywhere else, there is gravity.
Back to warm-up: Which direction is the force on a ball after I drop it?
Gravity
Why doesn't satellite fall to Earth?
Back to warm-up: Which direction is the force on the orbiting earth ball?
Review of Centripetal Force
HOW STRONG IS IT?
Relatively weak (more on that later)
RANGE? Infinite range
EXAMPLES
why objects fall
limits our jumping height
determines structure of galaxies and universe
Inward force on orbiting object
Velocity keeps object from falling
Force prevents objects from going straight
Pencil indicates a good time to take notes
WHAT IS IT? force between electrically charged particles (attracts and repels)
Electromagnetism
HOW STRONG IS IT?
10^36 times stronger than gravity!
RANGE? Infinite range
Back to warm-up: Which direction is the force on the magnet?
Electromagnetism
http://www.polleverywhere.com/multiple_choice_polls/MTAwNjI1MzU0OA
Which type of force keeps the electron orbiting the proton?
What keeps the protons stuck together?
EXAMPLES
keeps protons close enough to form bigger atoms
responsible for energy of nuclear power
WHAT IS IT? binds protons and neutrons
Strong nuclear force
HOW STRONG IS IT?
10^38 times stronger than gravity
RANGE? 10^-15 meters (about the size of proton)
Quick review

What is the difference between a proton and a neutron?
http://www.polleverywhere.com/multiple_choice_polls/LTE1NjcwMDkwMjE
EXAMPLES
initiates hydrogen fusion in stars
how we are all made of stardust!
WHAT IS IT? changes protons to neutrons and vice versa
Weak nuclear force
HOW STRONG IS IT?
"only" 10^25 times stronger than gravity
RANGE? 10^-18 meters (within proton)
Quick review

The weak force does which of the following?

Rank the strength of the four forces:
http://www.polleverywhere.com/multiple_choice_polls/MjAyMjUzODI1OA
http://www.polleverywhere.com/multiple_choice_polls/MjA4MTc0MDAyNA
Shanna Shaked
UCLA Physics Lecturer
Full transcript