Fluids, Buoyancy, and Archimedes' Principle

Archimedes is not just the owl from the Sword in the Stone. Although that's a sweet movie if you haven't seen it. He was also an old Greek dude who figured out a bunch of physics way before other people did. Some of this was discovered at bath time, so it has a lot to do with water, but don't get all weird about it, just listen to the old man in the tub. He's smarter than he looks.

Check out "Is This Wi-Fi Organic?", my book on disarming pseudoscience!

[MrSupernova]

This was extremely well explained and presented. I'm 20+ years out of high school and was curious about this topic. I tried other videos but they are riddled with so much scientific jargon that I can't tell one term from another much less understand the topic at hand. Of course, they left some important things out making it more difficult than it has to be. You made this video understandable for everyone regardless of age or educational background - as it should be! Thank you!

[thisbedazzledgirl]

Everything i search about on youtube, professor Dave has answers for it. ❤

[jonadeleneragay]

this teacher is a hero. God bless professor dave.

[shaygame]

thanks so much for keeping your videos short and to the point! saves so much time when studying :)

[tristo_sestdeset_stopinj]

2:13 the text in the video: "the ship weighs less than the water it displaces, so it floats" - NOT TRUE. at 3:33 you can see the EQUAL sign between the two forces, because they are EQUAL. the ship weighs EXACTLY THE SAME as the water it displaces, so it floats. otherwise, if one force was bigger than the other, the ship would start accelerating.

[malayapaul]

yes there are enough subscribers but why doesn't anyone like the videos, so busy on your studies .He is the best teacher till date he should get a million miles per video

[BroughtonCF]

2:14 The ship weigh less than the water it displaces - This is NOT correct. The weight of the water displaced weighs the same as the ship since it floats. Correct?

[BeniBoyzGuitarSlamz]

Lifesaver mate. Needed to understand this to teach it to my Year 10s. Now I can properly explain it to them. The only video that made sense to me. Thank you and God bless.

[cranberrysprite]

Thanks Professor Dave!!! What a fun name and channel you have

[oscar-jr]

At the 02:00 the arrows showing the force are not proparlly sized which is an inaccuracy, my teacher got mad at me when i showed this video to the class.

[lightspd]

Thanks Professor Dave! Appreciate all the great videos.

[imcoolpramesh]

1:29 I actually worked in that ship for around 2 years.

[albdim]

This is a great vid. The only issue I have is the sentences "A floating object displaces fluid based on its mass. A sinking onbject displaces fluid based on its volume". It seems like there are two different 'laws' due to which the floating objects behave differewntly from the sinking objects. Hmmmm....

[daveb]

My eureka moment came to me when I discovered how to determine if an ant was female or male. It's really quite simple. Drop the ant in water. If it sinks girl ant. If it floats....

[aryanvaidya]

Professor Dave,
I have heard several formulas for calculating buoyant force on an object :
f = mg
f(b) = Volume displaced by object * acceleration of gravity * Density of fluid
f(b) = volume OF the object * acceleration due to gravity * (density of fluid - density of object)


Which equation do you use in what scenario and why? Please Advise. This video was very helpful

[echa]

well you said: The buoyant force will support the object IF the OBJECT IS LESS DENSE than the fluid (ρ object < ρ fluid) because the weight of the object < weight of the fluid (with the same volume). And about the ship floats you said: w ship < F buoyancy. The ship weighs less than the weight of the water it displaces, so it floats. HOWEVER, isn't it supposed to be W ship EQUALS to the F buoyancy (if they float??) or all my years in school I have been taught the wrong thing? It's equal because the weight of the ship has to be canceled out by the Fa and so we can calculate this: ρf.Vfdisplaced = ρobject.Vtotalobject

[jessicauseful]

Sorry this question is probably so basic, but just want to make 1) The volume of the ball = the volume of the water displaced because the ball was fully submerged? 2) The volume of the water displaced turned into 5000g because you plugged it into Density=M/V?

[goranmalmsten]

2:15 Not true. The forces must have the same value.

[MarinaMatic]

In maritime industry they say weight of the vessel and weight of the cargo but they express it in kg and tonnes. In order to calculate momentum of stability we need force × lever, but for force we input mass of the object (in tonnes). Is this because m × g (force) = V × g × density (buoyant force) and since on both sides g is equal we can "pretend to be smart/stupid" and say ship has deadweight of 10000 tonnes and loads weight of 500kg. I was great in high school in physics but when I went at maritime college they just turn my hair gray calling mass weight, and that area of the triangle can be calculated (side a × side b)/2. Teacher said that it is OK to do it like that since side a is very similar to height of c side... I do not care if they are the same in the 10th digit, area of the triangle is height times side divided by 2. I refused to call mass weight and I got low grade. Your opinion? (PS. I am a teacher now and I am working on my own book for students and I want to call it as it is, mass is mass.)

[victoriarodriguezdeleon]

Excellent explanation, thank you very much.