What forces (i.e. pushes or pulls) are acting on you right now? Most people can identify the gravitational force down, but there must be something else otherwise you would accelerate down towards the center of the Earth. The other main force on you is called the normal force. It is a force perpendicular to the surface that supports you, like the ground or the seat of your chair. You compress this surface and it acts like a spring, pushing you up.

Force is a central concept in physics. By analysing the forces on an object, its resulting motion can be determined. But what exactly is a force? The word force is used in everyday language in a variety of contexts, only some of which reflect the scientific definition of force. In this video, people at Victoria Park in Sydney are interviewed on their ideas of force and the forces that act on them.

What is a Force?

This shot of an actual golf ball hitting a heavy steel plate at 150 mph was taken at 40,000 frames per second at the USGA Research and Test Center in Far Hills, NJ.

For daily updates from the United States Golf Association, visit us at www.usga.org, on Twitter (www.Twitter.com/USGA; www.Twitter.com/usopengolf) and on Facebook (www.Facebook.com/USGA; www.Facebook.com/USOPEN).

Golf Ball Hitting Steel in Slow Motion

Theoretical physics is very complicated, and there is still a lot we don't know about how the universe works. Trace and Julian are here to discuss the four fundamental forces of physics, and why we're still unsure about a lot of things. 

Follow Julian on Twitter: https://twitter.com/jhug00 

Read More:
New particle could help physicists understand subatomic glue
https://www.sciencenews.org/article/new-particle-could-help-physicists-understand-subatomic-glue
"The discovery of a particle about three times as hefty as a proton may lead to insights into the force that holds the nucleus of an atom together."

What are the Fundamental Forces of Physics?
http://physics.about.com/od/physics101thebasics/f/fund_forces.htm
"The fundamental forces (or fundamental interactions) of physics are the ways that individual particles interact with each other."

What are the four fundamental forces of nature? 
http://science.howstuffworks.com/environmental/earth/geophysics/fundamental-forces-of-nature.htm
"As you sit in front of your computer reading this article, you may be unaware of the many forces acting upon you."

Fundamental Forces
http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html
"A force which can hold a nucleus together against the enormous forces of repulsion of the protons is strong indeed."

Where Does Gravity Come From?
http://www.universetoday.com/75705/where-does-gravity-come-from/
"Gravity. The average person probably doesn't think about it on a daily basis, but yet gravity affects our every move."

General Physics: Gravity
http://helios.gsfc.nasa.gov/qa_gp_gr.html#gravsource

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The Four Fundamental Forces Of Physics Explained

Force Introduction - Student Presentation 

Force Introduction - Teaching Presentation 

Force Introduction - Student Lesson Outline 

Forces Introduction is a lesson by Teach Science with Fergy, containing engaging videos, presentations and activities to help develop students' science knowledge.

What Forces Are Acting On You?

Science Resource Description