What is Escape Velocity? (Physics)

Throw a stone in the air, it falls back down. Throw it harder, and if you are very strong you might place the stone into orbit. Throw it even harder, and the stone might leave the Earth forever. The minimum velocity you need to provide the stone for it to do so is called escape velocity.

In this video, we look into the details of this notion that is so important to rocket science.

To truly understand the concept of escape velocity, we use an approach based on Energy.

First, we discuss the components of the energy of a system composed of two masses (A planet and a rocket for example). Then, we look how this energy distributes itself between kinetic and potential energy. This provides the grounds for defining and deriving the mathematical formula for escape velocity.

Then, it will be time to play: we will use this formula to determine the radius of a black hole. As an example, we will imagine that the Earth collapses into a black hole, and attempt to determine the size it would have.

The concepts presented here are aligned with many high schools’ physics programs. This is why was added at the very end of the video some exercises to train on (with their detailed solutions).

#escapevelocity #physics #gravity

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STRUCTURE OF THE VIDEO
00:00 Introduction.
00:30 Structure and content of the video.
01:42 The energy of a system of 2 masses.
03:14 The energy of a rocket-planet system.
06:19 What is escape velocity?
06:30 How to derive the escape velocity formula?
07:14 What is the event horizon of a black hole?
07:50 How to calculate the size of a black hole?
09:11 Quiz: what would happen to the moon if the Earth became a black hole?
09:30 Escape velocity - training exercises.

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VIDEOS TO WATCH:
Gravitational potential energy:
What is Energy:

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MUSIC ALBUM
Physics Made Easy « The soundtracks ». Listen to the it here :

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CREDITS:
The script, the illustrations, the music and the video were produced and presented by Edouard Reny, Ph.D. in solid state chemistry and private tutor in Physical Sciences.
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DO YOU NEED HELP WITH YOUR HIGH SCHOOL PHYSICS?
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[PhysicsMadeEasy]

Hey Physics Lovers,

In this video, I use the concepts of energy and gravitational potential energy quite a lot. If you need a little help on these notions, check out these videos :

One viewer kindly made me notice a typo at the beginning of the video: I missed the ‘s’ in the word “Understanding” … Apologies for that!

If you have any questions, feel free to drop them in the comments!

Enjoy the video!

[bstanis]

Thank you so much Dr. Edouard, please, keep going, it is the best channel of physics, it has
very good explanation with animation and also English subtitles for us as we are foreign learners.
I'm so appreciative and thankful to you :)
We are always stay tune for your videos with passion,
Best regards with deep respect.

[gauravrudramalik]

A very nice video, and beautifully explained as always! :)
Coming to the answer, the orbit of the moon around the earth would be largely unaffected, even if the earth were to become a black hole. This is because the mass of the earth would remain unchanged and so would the distance between the centre of masses of the earth and moon, and also the energy equation would remain as is 😀

[garychen]

This is very very helpful! Thank you so much!

[Asaad-Hamad]

As usual.. Wonderful easy to comprehend explanation 🌷🌷

[munchyslime]

This is a gret video. I watched it to the end and learnd so much, edoard :)

[manuelsamuel]

Hi, great video
Could you please make a video elaborating on how current and electricity truly flows. I have always thought of it as water flowing through a pipe but recently came to know it's all electric fields provided by surface charges and the battery that propagate energy. Still finding it hard to wrap my head around it. Would find it helpful if you could provide a deeper dive.

[Sayan_]

I love your videos sir. Please keep posting ❤

[study-qysx]

hi sir, I love your videos. Can you please explain the virial theorem? What does it mean, and what is it used for? There are very few videos on this theorem, and I don't understand. Thank you

[SakariEklund]

I gave some thought to your quiz.

My thinking is that if the Earth would become a black hole, I suppose the Moon would leave the Earth, because Moon's acceleration towards Earth would get SMALLER (a=v^2/r) because the radius r would get BIGGER, thus the force between Earth and Moon F=ma would get SMALLER.

[deanchadwick]

The moon would surely stay on the same orbital path as the earth has the same mass

[Science-dq]

According to Einstein, , Gravity is not a Force. So F= mg is wrong??

[siddharthakumar]

Does bookish learning makes one idot in a true sense? comments your answer

[frowningJoker]

I was gonna watch the whole video, but at the beginning you missed an "s" in the word "understanding". There are millions of "content creators" on youtube, and if you want to stand out, and pull in more viewers and subscribers, show us that you take it seriously and at least do a spell check before posting anything. I hope that helps.