Gravitational Fields - A Level Physics
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- Опубликовано: 29 июн 2024
- Continuing the A Level revision series covering, fields, the gravitational field, the gravitational constant (G), gravitational potential energy, gravitational potential, the velocity and period of masses in orbit, geosynchronous satellites, Kepler's laws and escape velocity
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"It is terrible to do so but I have blocked out the sun" haha I love your videos you're awesome thanks! :)
i heard he watered out the sun lol
This is far more intelligent than A-Level students! All the A-Level students I knew at school were thick!
My physics teacher is crap, so i have to teach it all to myself and this really helps, cheers man!
Same bro, how did your exam go?
thank you for making physics less intimidating, i have you to thank for if i score well in my upcoming A levels :)
Celyn Tan Thanks. All good wishes for the exams.
At 8:30 the gravitational potential energy is the work done to bring a mass m from infinity to a distance r from a mass M. That is obviously negative since PE reduces as you get closer to the mass M. But PE increases as you move away from the mass M.
Sometimes its the tumble dryer.
if only there was a drchemistryA level
Did you find any ? I'm struggling to find one myself. I did for the record find a channel called allery chemistry but I didn't really watch it's videos yet.
Niket try a guy called E Rintoul
Thanks
Allery chemistry, clearly the best!
E Rintoul
what surprised me was you took the time to explain mv2/r. it was taught a long time ago to me and certainly I forgot and didn't understand this when I was watching you. Every aspect of your video revolve around the student and that is why this is so great, clear, engaging and easy to understand!
Very well explained. Will check out your other vids. Thanks for uploading!
Sir you're the best! I wish there were more teachers like you.
You can choose your own convention for signs. The one I am using assumes that potential energy becomes zero at an infinite distance away. Since potential energy increases as you go further away that means it must be negative in order to increase to 0. But as long as your signs are consistent it doesn't really matter what convention you choose.
Awesome stuff, such a huge help! I love all your videos.
Damn he provides a whole new perspective. Thanks sir.
Thank you very much for this video. I honestly have learnt alot from this! Will be looking into more of your videos soon! :)
I am delighted to hear it. Well done.
Force is a vector quantity. It has magnitude and direction. The negative sign is an indication that it is an attractive force (ie the force is in the opposite direction to increasing value of r). You don't have to include the minus sign as long as you remember which way the force operates.
Excellent lessons. I am thrilled to have found these video lessons. Thank you. Thank you.
Washing machine in the background
+John Fletcher or a work against gravity....
+John Fletcher i kept thinking it was mine
I thought it was a kettle
There was also a cow....
Abeel Goraya sounds like at around 6:00
A field doesn't do anything until you put something in. Like a temperature field that just sits there. Fields are capable of doing things, whether they do them or not. Put a block of ice in a temperature field and the ice melts.
That's a brilliant start to the video! 🙌🏽🤯🔥🎊
you sir, deserve a medal!
cheers
thank you very much i find your videos concise and extremely helpful !
Good Luck on your IB physics exam tomorrow! I'm taking the same exam and I agree, these videos are indeed very helpful!
Thanks DrPhysicsA! :)
Yes, from the centre of the earth to the centre of mass of the man. But I was ignoring the extra meter or so in 6400km.
Thanks so much DrPhysicsA, your videos are so helpful! :)
this channel is too good
i LOVE this, the explanation is good and easy understand.TQ so much ^^
Yep. Its a cuckoo clock with a cow instead of a cuckoo.
This video really helped MR thanx!!
Wow ! The best physics teacher ever ❤️
Great videos, thank you!
15:26 Moooo!
It is the mass of the earth. The mass of the satellite cancels out at an earlier stage so does not feature in the equation here. Thanks for kind comment.
the vedio made me understand more stuff then i understood in the class
so thank u sooo much
such a wonderful explanation, thnqw
These videos are so helpful!
Love your videos!
I take it you mean at 21:47 where I say r = 4.23 x 10**4 km. I haven't yet double checked it but could it be that you have calculated the value in m not km - in which case it would indeed be 4.23 x 10**7 m.
I may not have followed the point you are making. But if you square both sides then you will indeed get an expression without the square root. But then the left hand side will be T^2. Or have I missed the point?
ur video is really a good tool for revision
thank u :)
6:42 - It sounds like there's a rocket preparing to launch.
Thank you so much! these are very useful!!
Calculate the force on the 3rd due to the first and then the second using F = GMm/r^2. Since the forces will be in opposite directions the net force is one minus the other.
I learned the whole topic and more in 30 min than my school teacher who teaches us for a week and i learn 0 from him. Please make more.
I was in year 6 when this was filmed...
This really helps. THank you so much
Thankyou So much SIr you explained really in great manner :)
Fantastic videos.
There are so many books that I cant organise according to them all. I try to organise the videos in some logical order and hope the titles explain what they cover. I'm not sure what your Unit 4 OCR covers. Is it nuclear and particle physics? If so, there are videos on this in the A Level playlist - and more advanced videos on both in other playlists of mine.
Thank you for your videos. They are reviving my interest in Physics from 50 years ago when passing the exam was more important than understanding what you are doing
I am a bit confused about what is the difference between Gravitational Potential Energy (about 8:05) and the more conventional mgh kg m²/s² as you mention in your Electric Field Video comparing the two (at about 11:34) Substituting values for the variables they certainly don't agree. Many Thanks.
Drops lid whilst talking
*oops*
continues
btw thanks so much for these videos, it has helped me understand mechanics a lot better than how my teacher explained it.
Sunny? In the UK?!
Thank you, your videos helped a lot! I take IB HL physics but the topics covered are nearly the same ( from the videos that I've watched) so it helps a lot.
Hi sir woaaahh just wowwww i really love physics and you have deepen it
Yes. If you think of the earth and the sun, the gravitational force from the earth to the sun is directed towards the sun whereas the distance vector from the sun is measured away from the sun. The key thing is not the minus sign but rather that you are consistent in your signing convention.
The arrow on the Gravitational field line points towards the larger mass. Always.
Ur video rocks
Very helpful
Amazing videos.
Thank you, It was very helpful.
This was posted 10 years ago but my God you are good....
Thank you so much. This video is very useful for me :)
WE NEED YOU PLEASE COMEBACK, IT VERY USEFULL IN PANDEMIC (2022)
great video, very clear and engaging. Thank you sir.
as well as logical
Thanks for the derivation of T.
yh sure my teacher is a no brainer, n wif vidz lyk thez lyfz made a lot easier......................anks a lot man, u da best
Thank you so much.
Gravity is the curvature of space time. Objects are not pulled towards earth they are are essentially pushed towards earth because the earths mass bends the fabric of space around it. Most people say the suns gravity causes the earth to orbit the sun. But in reality the sun warps the space around it, which pushes earth towards the sun.
Mr genius every one knew it . but this is simple Physics IT DOES NOT INCLUDE RELATIVITY
kurdman12345678 The curvature of spacetime due to earth does not push objects towards the earth rather when a object moves near the earth it tries to move in a geodesic path (path between two points that has the shortest length) but due to the curvature of spacetime around earth those geodesic paths are curved which tend to converge towards the earth.
kurdman12345678 gravity is a force but doesn't bend space time because if it did you wouldn't age on the moon because it has less gravity
yo man got a B in physics, and i thought id thank you if i did cuz i swear to god i didnot know a word 3 days before the exam. i actually had to the buy the text book then cuz id lost mine, your videos saved me. thankyou very much
At 21:13- Period of geostationary, orbiting body: one sidereal day, 86,164 seconds.
I assume you are referring to the section starting at about 11:23. You are right in all you say except "small v is the length". This is a vector diagram so v is velocity not length. See my video on adding and subtracting vectors for tail to tail subtraction of vectors. So v on both sides of the equation is velocity.
Hello sir. Very nice presentation.
Thanks a lot!!!
What a great teacher you are. Thank you for your videos.
Could you make one describing the simple two bodies system and the equation that follows ?
There is a video in the A-level playlist which looks at momentum in two dimensions.
DrPhysicsA Thank you for the reply. An interesting video indeed. But in fact i was thinking of the two bodies problem in the planetary context. I have read something with a reduced mass to write the exact equation of the movement of a satellite which ends with this r = K²/(GMt( 1 + e cos θ )). I didn't understood how to arrive to this result. I was hoping you could shine some lights.
(Sorry for poor english)
Great videos!
P.S. Your voice reminds me of Mark Halliley (The Apprentice Narrator).
Thank u v much for the content. Just one clarification though, If the total energy = KE + PE, when the object moves to infinite distance (r=infinity) both become KE=PE=0. However when r 0, Infinity and make it equals to (mv^2)/2, then I can get the same escape velocity. But still cannot understand what happened to all PE. If somebody can help me, really appreciated. Thanks.
Thank you sir ❤🌑
Thanks so much. :)
What is the speed falling from space to earth with a changing gravity strength. Do you do a video about this?
That's interesting... correct me if I'm wrong, professor, but considering that the centripetal force on the object is F=mv^2/r, does that not mean that the kinetic energy of a rotating body is F*r/2? That is an amazingly cool way to find that.
This guy is adorable!
Two weeks before midterm Statics & Dynamics exams my British professor said that we could skip the next week's classes to study for the exam, but suggested that we show up anyway because he would "revise everything we have learned thus far". I almost passed out... in American usage 'revise' means 'change what was previously looked at', so it sounded like he was tossing out everything we had previously studied and replacing it with something else.
I really like the proof of centripetal acceleration= vsquared over r
Ive never seen it because most teachers don't explain why that is
I had the same issue. If you square the whole expression, (2 x pi x r) / v, while substituting the root GM/r for the v, you get the expression you derived without the square root in the expression...
if you listen very closely you can hear your brain frying
You need glasses.
The minus sign is there as gravitational force is attractive. I get the distance in the opposite direction of the force, however that will just confuse students (why cant they measure from bottom to top etc.)
So helpful
Yes, that's what I did *headdesk* thankyou very much.
Thanks! Unfortunately though, CIE tends to ask why there is a negative sign, and they don't accept the direction argument.
For escape velocity, assuming a conservative system where
we end up with the kinetic and potential energy of the system as:
K_f + Ep_f = K_i + Ep_i,
where sub 'f' is final and sub 'i' is initial, should we not set up the equation where the left side is 0. The final kinetic energy and the potential at infinity would be zero. That leaves us with 0 = 1/2mV^2 -- GMm/r.
This rids the (--) as shown in 26:31 when we rearrange to get 1/2mV^2 = GMm/r.
you have helped a lot over the past few weeks of revision for me. got my first A2 exam in just under an hour. I will let you know how it goes in a couple of months time. (predicted A, although will be happy with a C).
Fingers crossed I guess!
Dan Hyde good luck. Hope it goes well.
I wonder if it went well.
Zarish Ahmed got a B so I was super happy. Completely forgot about that comment.
You're the best, forget the rest.
Good Day Sir, could you Show us how to calculate gravitational Potential energy at earth center?.... Thank you.... 👍👍... Very well explained Video Sir
No I am only squaring 2 pi r so I can put it inside the square root.
please make a video on example exam style questions
Thanks ❤❤❤❤❤❤❤❤
technically gravity is just the result of the curvature of the fabric of space time and is not a pulling force. a large mass would curve or distort the space around it like rubber sheet being distorted by say a bowling ball. essentially other masses would "roll" towards the center of the distortion (like a marble rolling down the curve in the rubber sheet we talked about earlier made by the bowling ball). so gravity is not a "pull" but a "push.
still like your calculations
Do you have a video on the gravitational potential graphs etc. please?
in my book says ' the magnitude of minimal velocity of a rocket in order for the rocket to be able to escape from grabity is = square root of 2g× m over r. is that correct ?. there was one similar except it doesnt have a square root
oh thank you.
Sir, it would be helpful if you could tell me where I can find the video on electric fields. Its not there in your classical mechanics playlist.
ruclips.net/video/GDFpTefpDME/видео.html
Question: In the video, you say velocity, v, is a vector, but then you say it's speed at 12:32. How do you convert a vector to a single variable like that?
Recent studies have shown that Gravity= speed+energy, not Mass. Books will need to be re-writen.
Really? I struggle to see why. G is a constant. M and m are both scalars. F and r are the only vectors in the equation. And F is in the opposite direction to r. It may be they want you to say that Force is the differential of potential energy and PE is always negative (because it increases as you go further away from the earth and is 0 at infinity)