Conservation of Energy: Free Fall, Springs, and Pendulums
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- čas přidán 12. 03. 2017
- The energy of a closed system is always conserved. This is an important law of physics! But energy does change forms. What are all the forms, how do they interchange, and how does this apply to things like free fall and pendulums? You gotta watch this clip to find out, buddy!
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I have a hard time understanding physics when there's no too much theory, but your videos are the only ones who make me understand 100% everything in physics. I want to say that thanks to your videos I got the best score in physics of 100%
Yo this is literally primary school math drop out of high school if you don't understand any further...
Indian PUBG player Why so rude though?
@@stop2759 Sorry I was a bit rude; I was just trying to sound blunt to give this guy a reality check. If you can't understand the basic maths, then you're going to have trouble with all physics in later years.
@@pubgplayer1720 sometimes it's the teacher, the way it's explained, or it just isn't their passion. give it time and they'll be alright.
@@pubgplayer1720 physics needs to be explained with theory not just the use of equations, as that will help students broaden or lighten the topic they're dealing with.
For the past five decades, having flunked out of premed (remember, this was the '60s) I have still yearned to truly understand physics, chemistry, et al., simply for the sheer pleasure of understanding how the Universe works, what it is made of and its history. I've tried periodically many times over the years to initiate this understanding, since I have a large quantity of science textbooks I've purchased over the years (some applying calculus and some not). I start out full of resolve and optimism, I solve some of the problems. But soon enough I'm not able to solve them anymore and my energy (I'm using the term strictly in its colloquial metaphoric sense-- I understand its definition in physics) flags and I give up. I was always left with a feeling of frustration, because the yearning remained, despite the futility. Then, I discovered your tutorials and now I'm finally grokking (again with the '60s) these concepts and solving the problems. .And, at 75 years old, just in time. Grazia tanto, Signor Professore!
I love how simple and easy you make these concepts seem, my tutors over complicate EVERYTHING and their lectures leave me more confused than before I started! A class mate recommended your videos over the lectures and I'm so glad they did because I'm now understanding things in 5 minutes that before would of taken me weeks of sifting through my tutors overcomplicated jargon to reach the same understanding. I wish all professors were as clear cut and concise as you, keep up the good work educating the masses, love your content!
I wish all classes and lectures were just like this. Straight to the point and effecient
i can't express how satisfying it is to try to solve the problem at the end of the video and then get it right first try.
thanks prof dave!
Thank you so much, I have been trying to figure this out for 2 days. The teachers lecture is very unhelpful in using the formula even though he took 2-3 hours to explain it, the textbook literally has only solutions for F=kx which made it impossible to even use the textbook. I can't believe how hard it was to even find a proper explanation on google, finding your videos is a godsend. I can finally answer the 4 questions the teacher has posted. I really really like physics and the idea but good explanations are so far and few.
So grateful that these videos exist! Unfortunately, professors can have a great understanding of physics but little ability to pass that understanding on. You, however, do have that ability!
And, of course, you amply have the great understanding, inasmuch as you know a lot about the science stuff.
The intro felt like a fever dream ;-;
;_;
Excelente, excelente, excelente, profesor Dave. ¡Saludos desde la República Dominicana!
sir ur physics videos are absolutely clear with the concepts ..thus help students to understand them easily
Thank you i really gained alot of value from this
4:25 my heart is beating. im waiting for this moment! "did I calculate right?", "am i a loser?"! this is the most interesting moment
omg, I have the exact same feeling when I get the results of a physics test! Dang!
@@Matt-sc6gg same
Very helpful! Tysm for making this video :)
Very nice explanation.thank you
Your videos has helped me to understand physics
Thanks for the videos!
Thank you for the video!
thank u professor Dave I rlly needed this
hey its me again
love your simplicity !!
How can you find the maximum height of an object? I'm learning this unit in class and it was really confusing but your video explained it really well.
great video! thanks!
Helpful & to the point..thank you!!
Dang who else teacher told us to watch this video to compete the assignment
You in college?
@@05bahaafarah11 Nope I was in 9th grade when I made this comment I’m a senior now
Hahahah yep
The only non indian guy I can search up when I am in despair.
thanks Prof. Dave! This helped sooo much!!! All the love from the Philippines! :)))))))
Bakit konti lang subscribers niya??
Magaling kaya siyang mag turo
Good teaching sir 👍💞
The most useful video ever😍
eljko Milković, an academic and inventor from Novi Sad, has done something great that has not been done by any Serbian inventor before.
Milković invention of the mechanical oscillator is widely used worldwide, a testament to the fact that over 500 foreign companies use, sell and manufacture pendulum-based machines used in the heavy industry.
The purpose of the two-stage meganic oscillator is multifaceted, because the character of the machine (two-arm lever with pendulum) allows its use as a press, water pumps, compressor, crusher, power generator, mini power plants.
love the intro! iconic
Sirr you explain this topic in very easy manner thank you......
Thanks professor Dave, very informative. Pongan listo!
what an absolute saint. u are the best teacher!
He is the science god
Please give a video about simple harmonic motion for pendulum with examples
Thank you professor
This Man is really good
you can also get the answer of the last question by using
v^2 = v0^2 + 2as formula
I always watch till the end just to listen the end music :)
How did you get the initial velocity? Or the final velocity?
Thank you very much
how did you solve the problem in the checking comprehension?
what will be the mass of object at the start of swing, middle of swing and at the end of swing during one cycle.
Thankyou Sir!
This is great
dude, thank you.
very good
dude your intro song is meme lol it is pretty funny to and like your content of teaching others like a teacher but in a short way
thanks! this video is really helpful especially during this time of pandemic where im not attending school. honestly this is better explained than my teacher! Keep up the good videos!! :)
lol dis is 2 years ago
@★SW4GGYP3NGU1N★ -OMG TYSM FOR 50 nah 10th or 11th maybe
when can i use g or -g? does velocity a vector?
Nice lecture sir... Love from India ....🇮🇳🇮🇳🇮🇳
1000000 thanks for you explanation
Hey prof could you pls release the vid of conservation of linear momentum asap
This video helps me a lot thank you!💙💙💙💙
Hi, is there any formula for pendulum lever length periods for the free fall pendulum from 12 o`clock when potential energy on 12 clocks is zero?
Free fall pendulum is an oxymoron. The bob is still supported by the constraint force in the rod and pivot.
There is no closed form equation for high amplitude pendulums, where you can't approximate sin(theta) as theta. You can solve it with an infinite series if you need to model it, but you cannot get an exact equation in closed form for the period. It also no longer undergoes simple harmonic motion, when you can no longer take credit for the approximation.
Hyperphysics has a large amplitude pendulum period calculator, that enables you to see this effect.
How you'd come up with the final velocity of 1,640?
I know like how
If physics is the study of the natural physical world, mathematically observed, noted, studied, & expressed?
What about the vibration behind the thermal energy output by our first, most important muscle, the brain, teacher?
Pls explain mechanical energy is conserved for a system here only ball is there
Can u tell why does the speed (v) decreases on going upwards?
Because acceleration due to gravity is constant and points in the negative direction, acting on all projectiles and decreasing their vertical velocity all the time.
U are a good guy professor Dave luv u sir♥️♥️
what are the potential energies of a Blue Shell vs Red Shell vs Green Shell? If you're in 1st vs 2nd vs 3rd place?
If you're a stud, green is all you need.
good video
bravo Dave. goo joob
Thanks
I love you, you are one of the best teachers 😍
hi! thanks for the video! a great one...one note though - we do not need to know the mass on the comprehension section to calculate the speed ta 20 meters as it is cancelled out for the equation
I’m confused on how you got velocity
thanks
In the comprehension test, the object falls toward the ground, isn't the g = (-9.8m/s^2)? Why it is positive?
good question, i think when it's g and not a, we just use the scalar value rather than the vector so we ignore direction. may want to double check but i think that's correct.
@@ProfessorDaveExplains Thanks for the respond :)
Done.
Sir is both kinetic energy and potential energy are mechanical or thermal energy?
They both are considered mechanical energy.
Thermal energy ultimately is kinetic energy, except at the molecular level, instead of macroscopic.
Ty
Would this be the primary reason a magnetic motor can never provide more energy then is put into it?
4:43 u can also do this with Vf^2 = Vi^2 = 2a(delta)x and get the same answer which proves these equations relates to one another :D
Is the conservation of the energy found in the way it is transformed? I'm trying to understand what you mean by conservation of energy...like it's saved? or more precisely not lost? because it goes from one form to another? Can the conservation be measured? Thank you for your videos, they're great ☺.
it means the total amount of energy remains constant for a closed system! the amount of energy can be measured, yes, we just have to account for all the different forms of energy. thanks for watching!
Conservation of energy means you cannot create or destroy energy. It only changes form, and changes what object contains it. The sum total energy in an isolated system will equal a constant value. Isolated system means no mass or energy crosses the boundaries of the system.
How is the energy of a closed system conserved if ,according to the 1st law of thermodynamics, says that adding heat can cause a change in internal energy? Even though the system has no mass transfer the internal energy can still change. Maybe I just don’t have the right idea
Energy can be transferred in or out of a system. That's not a violation of the 1st law. The energy has to come from somewhere or go somewhere. It's conserved.
Professor Dave Explains I was not taking the surrounding into consideration. Thank you
Pls àdd a vedio on time period of pendulum
I am stuck on a problem, this is because there is no velocity given at ALL. How could you find the velocity without having the initial information (No time, or acceleration of the object falling was given)? I did try using the conservation of energy formula yet the answer came out to be no solution!
I guess you have to assume that the initial velocity is 0
Professor, I had a question. If you would answer this, I will be very grateful.The question is:
An object is in free fall when the force acting on it is exclusively gravitational. But why then the moon is in free fall? Isn't there centrifugal force acting on it?
Thanks professor.
Lots of love.
I guess the gravitational force is contributing to the required centrifugal force.Feel free to correct me if I am wrong. :)
@@adithyank3773 Centrifugal force does not exist.
Lynxica is correct. It would be centripetal force acting on the moon' gravitational pull.
The moon is in free fall around the Earth. However, due to the fact that the moon has sufficient tangential speed, the moon is continuing to overshoot its target, which is why it doesn't crash in to the Earth. If the orbit were a perfect circle, the force of gravity would directly match the net force needed to cause centripetal acceleration. The force of gravity would be entirely perpendicular to the moon's velocity, which means there is zero work done by the force of gravity on the moon, and zero change in speed.
The orbit is not a perfect circle, so to a lesser extent, the moon does speed up slightly and slow down slightly. The path of the orbit is elliptical, with the Earth-Moon center of mass (which is inside of Earth) at one of the focus points. You can look up the apogee (farthest distance from Earth) and perigee (closest distance from Earth) of the moon to see how far it varies from a perfect circle. There is the parameter called eccentricity that is also a measure of how non-circular an orbital shape is. The moon does speed up as it approaches perigee and slow down as it approaches apogee, so gravity does do a little bit of work on the moon during this path, but not enough to put it on a crash trajectory with Earth.
if the object is falling, that means g is negative and h is negative . Right? so that's why you got positive answer (the negative cancelled themselves) .. instead of negative ????????
I always get confused with g. sometimes it be positive and sometimes it be negative. Please help!
The reason its sign changes, is that you assign a sign convention and coordinate system as you see fit to solve the problem. In any event, the gravitational field g acts downward, and your assignment of signs needs to account for this, as the downward direction fits your coordinate system. Sometimes it is more convenient to assign positive to the downward direction, other times it is more convenient to assign positive to the upward direction.
If a ball is on the ground,its potential energy is 0, but if I dig a circle around the ball so that the ball looks like as if it's on top of a tower, it suddenly has potential energy. PLEASE EXPLAIN HOW Prof.
ooh good one! i think it would still have zero potential energy, it would only have potential energy if it were rolled off the edge such that it could fall. that may or may not be right!
so if I am on top of a mountain and its highest point is at sea level. does that means I don't have PE until I get rolled off the mountain?
Gravitational potential energy is relative to whatever you choose to be your datum. If you calculate total mechanical energy based on that datum, it will be conserved in a closed system either way. You just can't change the datum at any point during your evaluation.
Was the potential created by removing the circle of dirt?
Good question. It is arbitrary where we define GPE to equal zero. A ball sitting on the ground doesn't necessarily have truly zero GPE, we just define it to have zero GPE by convention. It is mathematically impractical to calculate how much GPE it truly has.
We define its initial GPE to equal zero. We then dig a hole 1 meter deep. We let the 1kg ball roll toward the hole. The ball falls to the bottom of the hole, and its GPE becomes -9.8 Joules. The ball lost 9.8 Joules of GPE that became thermal energy, when it falls and comes to rest.
When using the universal law of gravitation, we set GPE = 0 at r=infinity, but this is just for mathematical convenience. When we do this, all GPE's end up becoming negative. It is a simple consequence of picking r=infinity as our datum for GPE for mathematical convenience. There is no such thing as absolute GPE, the way we calculate it in Physics.
what happens if a glass ball and a metallic ball of same mass are dropped from same height? which will reach first? this question was on my test under electro mag.induction. i know its a bit out of context here but can you help plz?
ooohhh you mean like will the metal ball have its rate of free fall affected by the magnetic field of the earth? very interesting question. i would be confident that any impact would be negligible and we could not detect any difference. however the more fundamental question of whether there would be any difference whatsoever, even if not measurable, is pretty interesting, and i'm not sure of the answer.
my guess is that in order to stop the current from inducing there would be a decrease in its speed, so that energy remains conserved. im not that sure though since current itself gets induced in accordance with energy conservation (lenz's law).
wgt a pendelum does not hit a person's face without flinching. when released at the same point at a given distance?
why?
@@hajimajinja4941 Because energy is conserved. There is no energy added to the swinging pendulum, when it fell from the person's face, to the opposite end of the room, and back to the person's face. The pendulum can go no higher, than the point at which it started.
Time would need to run backwards, for the air drag and friction to do positive work on the swinging pendulum, which would speed it up. As crazy as this sounds, it is perfectly OK with the first law of thermodynamics. It is the second law of thermodynamics, that makes forces like friction and air drag slow objects down instead of speed them up.
how did you get 1,640 for Vf^2 ? I cant recognize the way of solution. All in all thumbs up for easy understanding
just simplify and solve! basic algebra, check out my algebra tutorials if it is confusing.
Thanks a lot ! 🤩
So, which is correct? GPE > KE + SE + HE, or GPE > KE > SE + HE ?
Thank you PHYSICS JESUS!
Not sure how he got to v^2 = 1640. How did that work? I have a test on this sooooonnnn
all the arithmetic is there! don't forget to square that initial velocity.
@@ProfessorDaveExplains Could you please explain it briefly as a reply. I'm not able to understand how you got 1640. Would be appreciated.
Is it correlate with projectile motion. I use it and result is the same thanks
@@lorihunter1429 Thanks for that tip, I actually struggled with this problem at first but your comment made me finally solve the equation right.
Legend.
I have a question, how did you solve for its final velocity?
square root of 1,640 = 40.5
Using v² = u² + 2gh formula you can solve= it.... Here I am explaining....
v = ? , u = 40.5 m/s² , g = 9.8m/s²
h = 20 m
So, v² = (40.5)² + 2 × 9.8 × 20
= 2032.25
So, v = 45.08 m/s²
So the final velocity is 45.08 m/s²
Все понятно спасибо
How does energy conservation apply to a fulcrum?
www.physicsforums.com/threads/law-of-the-lever-conservation-of-energy-or-angular-momentum.833317/
Your theme song should be on the grammys.
shut up kendal
3:46 who else decided to slap the table
I did not understand what 4:44, well the working out meant 😔😖
If we are energy then once our bodies (matter) die, will our energy continue on? Since energy can not be destroyed then this kind of makes sense.
This of course doesn't mean that energy of yours would have your consciousness nor memories.
Well as you say, we are energy in the sense that we are made of matter, and when we die, that matter persists. Our bodies decompose and the atoms go on to be part of other things, like the ground, and a tree, and the air, and so forth.
@@dixztube Sure, I suppose that's one way of putting it.
Huh, I thought it was 9.8 meters per second. Or is that terminal velocity?
9.8 meters per second per second is the acceleration due to gravity on earth
he is the only reason im halfway passing school 💀
The goat
Nice
Te rifaste gracias
2:32 What about air resistance?
Yes
Tysm 😭😭♥️♥️
Love from India ❤️
Dave Grohl’s Cousin over here.