What Forces Are Acting On You?

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.

[pfeifferc]

Thank you, I am going to use this video with my 8th grade physics class as an introduction to force. Awesome job making it relevant and easy to understand. 

[veritasium]

The normal force is the sum of all the electromagnetic interactions between your shoes and the ground - so they're the same thing essentially.

[veritasium]

@MrLatrommi Most introductory physics courses draw all forces acting through the centre of mass because this avoids complexities due to rotational motion.

[JoelCarli]

I just noticed the disappearing/reappearing father and daughter in the background, haha.

[veritasium]

@bramshih This is a good question. The answer is Newton's Third Law is never violated. If you are standing still the normal force must be equal to your weight. If a table breaks beneath you, then the normal force is less than weight and you accelerate to the Earth. This doesn't violate Newton's third law because the equal and opposite reaction force is actually the force with which you attract the earth. Check out my vid on Newton's third.

[veritasium]

I've been trying to cover off the basics first, but hopefully I'll get there soon. I guess when I think of the forces on you, I'm thinking about forces bigger than a couple Newtons, of which there are only two. I don't know about kinetic friction unless you're sliding some place, and static friction is not an issue either if you're standing without pushing off anything.

[NasirMxd]

So technically speaking, the force is with me .

[mrsg]

Greetings from San Diego, CA. Wanted to let you know that we are using your videos in my 8th grade science class. They are terrific!! The students really enjoy your style of "teaching". Thanks so much!

[alldaygaming]

We studied friction last year so I recognize the normal force. But this is the first time I completely understand where that force comes from. Thanks Derek!

[nann]

so easy to understand!! real life saver, this guy

[mayankkr.]

I never thought of it this way, science is beautiful.

[Armaros]

Please tell me I'm not the only one who giggled at 2:05

[jackpaice]

duuuh of course. if it were just gravity we would be falling into the earth's core. why didn't I see it before?

[veritasium]

except what's reacting against what? I always find action/reaction designations confusing because it's unclear which is doing the acting and which the reacting.

[Leo-wmcd]

I would like to add another point:
- there is gravity, witch points down
-there is buoyancy, (density x volume x gravity) that comes from the air
-If we take weight(mass x gravity) and subtract buoyancy we get apparent weight
- the earth reacts with the normal force which has the same intensity as the aparent weight
So there are three forces acting on us:
-weight
-buoyancy
-normal force
OBS: sorry if i commited any grammar mistakes, i am brazilian

[HercadosP]

You forgot pressure. Air is squishing you from all sides while your body applies the same pressure to counter it.

[Pwndbythnb]

Mind Blown little girl and daddy there and gone 1:10. Magic of video editing

[willoughbykrenzteinburg]

Centrifugal force is an outward 'force' that is observed from within rotating frames. It is the result of inertia, and it COUNTERS the force due to gravity, so you have it backward. At the equator (where the rotation and therefore centrifugal force are the greatest), you feel lighter. At the poles, where there is virtually no rotation, you feel the heaviest.

Note : The Earth also bulges at the equator (due to the same centrifugal force) so the gravitaional force is also weaker.

[Tletna]

I prefer to think of it as we are bodies accelerating toward the center of the earth (since the earth has so much more inertia). When we contact a surface (say we just jumped up and fell back down to the ground) there is an a momentum interaction. If the surface we land on is softer or more elastic, our joints don't need to bend as much to prevent us from getting injured or bouncing. Yet, gravity doesn't stop, we're still attracted to the center of the earth and ground keeps pushing back....

[veritasium]

@nubbs haha, yes that's important - that's what the analogy with the spring is meant to be. That reminds me of the story "turtles all the way down." Check it out on wikipedia.