Kinetic Energy and Potential Energy

You can put energy into an object. Wanna know how? No, you don't need a Harry Potter wand. Just lift it up above your head! By doing so, you bestow the object with more potential energy. Learn more about the energy of motion and the energy of location in this clip.
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[@bebros2858]

bro is the physics jesus

[@lucidgen11]

💀

[@sharvenkumar364]

What????

[@mohamadjarrar8776]

Here I am studying MSc in Engineering but watching this rather simple video I guess I needed something as simple and clear as this video after being lost in the details, something like this reminds you of the essence of these basic concepts. It's not a shame to go over these simple terms (other simple terms also) every once and a while as I get some sort of refreshness and a slight smile of how things were nice and simple. Great video, thank you.

[@christospapaioannou928]

I dont know if anyone has noticed but Professor Dave seems to know a lot about the science stuff. All jokes aside our videos are really helpful and I watch them every time we learn a new unit in physics.

[@sotl97]

Professor Dave. You are frik'n smart man. Thank you for sharing this video on KZbin. You're the best!

[@bilas2645]

W= mad

[@purplestacks]

w: why you have to be mad at me?

[@saeedalshemeili5258]

Noble prize is for you

[@brauljo]

Wario's and Waluigi's origin story...

[@bunalatamohapatra835]

See W= F.d So now, F=ma That's why m.a.d

[@iluvdilfs4465]

😠

[@purplestacks]

I use to hate ur intro and the way you explain things. Lately I've been realizing that you are proficient when it comes to concepts especially when it comes to physics. Keep this subscription forever and I hope you continue uploading videos. Thank you for helping an electronics engineering student who is so terrible at physics.

[@YN-zv6ov]

@Ashay Playz he said sorry. And what do u expect the world is full of hate

[@heythere384]

Wow ! You defined potential energy quite perfect .

[@Akira_drafts]

2022 and still helpfull !!! The content he teaches in under 5 mins is just awesome ! Loved it ❤

[@nafyssacisse]

2023 and still helpful

[@RetroS01]

@@nafyssacisse 2024 and still helpful

[@vivitt4030]

True

[@kyuu2]

I feel so proud of myself actually getting the practice problem right lol. Thank you so much!

[@E-2.71]

I enjoy Professor Dave's videos, helps me learn subject better!!

[@dkwhattouseasusername1012]

Just discovered this channel but wow, really good, his explanations are simple and easy to understand

[@bloodline._]

THANK YOU SO MUCH! I HAVE TO WRITE AN ESSAY ABOUT POTENTIAL AND KINETIC ENERGY AND THIS HAS HELPED ME A LOT :)

[@clayton2117]

I remember when I was a kid jumping on my trampoline I’d take my mums keys and let them go as I was coming up or falling back down but what supprised me (besides the fact that the keys and I fell at the same speed) was that when I let them go as I was coming up they would go higher then me but then still fall at the same speed, back then I didn’t know what gravity was or that things fell at the same speed but it was so mesmerising letting go of the keys because they’d kind of just move in slow motion as they were faking

[@orb7828]

im watching this in 2020 and this rlly helped me. I love ur intro!

[@evan.5967]

I looked at your post date and it said "7 months ago" I was like are you sure it's 2020?!?! WTF it's been a loooong year :'(

[@johnjavidwrencedelacruz6081]

Me too

[@RJ-kb3qf]

Hey from the future haha can’t believe you wrote this a year ago

[@wacotaco7884]

hey from the further future, I don't know why I am doing this.

[@rogue4134]

Hey from further further future, i am doing this to ignore the work in front of me

[@studies9119]

Proffersor dave, thank you, I had a difficult time answering this question "in a frictionless enviroment, would an object of heavier mass have greater ke than a lighter mass?" until I watched this vid. Wish you the best in your future endeavours.

[@davidmudry5622]

As far as I'm concerned it's a lot easier to understand the truth of 9/11 when you realize Einstein's gravity, which Neil deGrasse Tyson says superseded Newton's gravity, does not accelerate objects down to the ground, and does not push objects down with a force. And when you do, you'll also realize objects need a support from below, where the one and only force that comes from below to give objects their weight, then you'll realize that nothing comes down unless that support underneath the object is first removed or weakened. And if that support below is weakened to the point where the object will become lighter, the object will then descend with the illusion of apparent acceleration. There are many, at least a dozen KZbin videos on Einstein. They all talk about Inertial Frames of reference, which both Newton and Einstein agree on, which it is when an object is not accelerating. They're both totally opposite as to when you would say an object, influenced by just gravity alone, is being accelerated. But we know it is a force of acceleration in ONE direction that is the explanation of why mass has weight in the OPPOSITE direction, like how you fall backwards when the bus takes off forwards...then you've figured it out who makes more sense about inertial frames of reference...Einstein was right, free fall is not acceleration, free fall is not kinetic energy, because free fall is weightless and is standing still. kzbin.info/www/bejne/e2WWXnacqtB4ndU

[@MrMarkgyuro]

just understood, thank you Professor! I have realised it is called potential because it is potential.

[@myprofilepictureisbeberexha]

Thanks Professer my school teacher showed us the video and it helps me alot.

[@seanfox121]

Thanks so much! This video was really helpful!

[@kennyhuang7393]

Have an exam tomorrow at 10:30 AM. Your videos are really helping me study last minute.

[@honeybee2145]

Concepts are very clearly and briefly explained. I like Prof. Dave's videos.

[@arshilzia3842]

I did it by other method First I found k.E 1/2×50×11.2×11.2=3136J As it transfers 1539J to another body so 3136-1539=1597J So new kE is 1597J 1/2mv^2=1597 1/2×50×v^2=1597 ( as mass is given 50) 25v^2=1597 V^2=1597/25 V^2=63.88 V=7.99

[@robertstewart3922]

I did it the same way as you @cartoon stories. I don't completely understand Dave's way of working this out. Would be good if he could add an explanation to his calculations.

[@arshilzia3842]

robert stewart yes you're he should add more explanation/information about equations or calculation specially in physics

[@kuiizoo]

I'll... just watch the video, thanks. but great explanation. :)

[@devikas.9088]

yep i also did it this way

[@sheikhamohammed5142]

Can I ask how we got the 7.99 at the end

[@erasmith3511]

Very nice explanation

[@michellekhoshaba4249]

You are a god sent, thank you!

[@LinkFreak9999]

Thanks once again! Love your videos.

[@mareged9978]

it would be so cool if you made versions of the videos with all the vector calculus involved

[@rollinginthedeep6900]

Thank you for explaining this! I was wondering why it was necessary to ascribe an object at rest "potential energy" when it hasn't moved and isn't necessarily going to. I was wondering why we can't just say it has energy when it's actually in motion. But the pulled arrow on a bow and compressed spring examples illustrated the point, and then the clarification that potential energy exists due to an object's position in a *field*, and often when we say potential energy we are talking about gravitational potential energy. I hope I understood that but that was my take away! Thanks!

[@luveeii]

Thanks this is really helping me I have an exam tomorrow and this will help thanks

[@sarinayaghoobian]

This man taught me in 4 mins what my science teacher couldn’t teach me in 4 months

[@michaelgalario6655]

@prof Dave, Just want to ask questions for clarification. According to the Kinetic Molecular Theory "particles of matter constantly move". Kinetic Energy by definition is often defined as the energy of an object due to its motion. At a macroscopic level, we identify and differentiate Kinetic energy and Potential energy based on the observable motion of an object. Simply, if it's moving there is KE (energy in motion). Otherwise, PE.(energy at rest). However, at the microscopic level, as per the KMT, particles that make up matter move constantly, and this is where my understanding of KE and PE becomes a bit fuzzy: 1. Considering KMT - particles of matter are always in motion, does Potential Energy form really exist? Hope you could give clarification on this.

[@thecosmosian10]

On microscopic level all energies are either Kinetic or potential as they are either created due to motion or particle interaction.

[@patriciaanders1332]

This was a great helpful video when discussing with my middle school student! Thank you

[@SanaKhan-zh9gw]

Ur kid's in the wrong school if he learning potential energy in middle school

[@harshitakaushik7771]

In which standard you are ?🤔

[@swagdork2584]

the intro was like a primary school teacher and then he starts bamboozling my brain

[@physicskiawazbabitaparmar4846]

Great explanation

[@youngsaxena2641]

you are great sir . thanks a lot.

[@trenek5943]

what a mad work :D

[@jonaswhenry9371]

it really helped thank you so much

[@kellangemaehlich7944]

your good i hope you get 1 million subs

[@stormingsharks]

I'm thinking that the reason for W being negative is for a similar reason that exothermic reactions in chemistry are negative. They transfer or "release" energy into their surroundings, which is represented by a - sign. Idk if this is a proper way of thinking about it, or if it's even correct, but it worked for me so I'm kk with it.

[@SuperCarbohydrate]

I have the same question as well. I cannot understand why it is a negative W

[@RetroS01]

Dave just taught me Hour 1-2 of Physics 4a in just 5 minutes, that's insane!

[@TheHalalCrack]

awsome explanation

[@gemmaleigh6051]

Our school played this for Science! :)

[@tinygiant6285]

Samee

[@gocommitbreathe21oxygen11]

you're luckyyyyy

[@SamuelGillIBAKAGY]

not very good

[@hihowareyou0000]

Great video 😀👍💖

[@johnnieltoncanonoy9129]

Thx for this content it helps me to understand and I finish my module in science I'm grade 7 from Philippines

[@CookieDookie145]

me too but im grade 8

[@dash_board2026]

Intro ... That's a great way to start a video

[@freepointsgals609]

This is the equation I came up with to solve for vf in the comprehension section at the end of the video. (2((w)+1/2(m)(vi^2))/(m))^(1/2)=vf What's wrong with my algebra? I'm extremely frustrated.

[@zohatariq1233]

If work is done on the system then sign should be negative?

[@EMH-ov8hq]

Professor why put negative sign in 1539J .plz can you explain me.Thank you Sir

[@SuperShana97]

Your video was short and helpful compare to other videos. I kinda got the material gradually. When I do the problem, I almost got it except the negative signs. I wonder why is negative ?

[@SuperCarbohydrate]

same question

[@SuperCarbohydrate]

I want to know why as well:(

[@watermeloneo]

5 years late but its negative because the question states "1539J of energy is transferred" implying that its work done BY the system which is always negative like professor dave said earlier in the video

[@niceguy4801]

Thankyou sir!

[@johnnyrottenpiss]

Cool jingle, dude.

[@hazimahmed8713]

As velocity is frame dependent, is kinetic energy also frame dependent?

[@lilosnitch3247]

Can i ask u something? Im doing some research and phycis say that increase in potential energy will increase kinetic energy.A bow and arrow for example or even throwing a ball.....but in fighting like boxing and muay thai, winding up(pulling your arms back) and developing power that way is actually ineffective and very discouraged. Can u explain how in this senario it becomes different please??

[@carultch]

"Increase in potential energy will increase kinetic energy" The opposite is true. Energy comes out of the potential form and converts to the kinetic form. Or vice-versa. This is what happens when no non-conservative forces come in to play. It is a trading of kinetic and potential energy. Human forces are not conservative forces, so the concept of potential energy doesn't apply to them. There may be parts of the concept that will apply.

[@EpicSelenium34]

I watched a video that proposed that potential energy is not stored within an object, but instead is directly associated with the system that the object inhabits. Since energy is not really a "thing" in the physical sense of the word (it is an intangible capacity), both perspectives seem equally valid. Which one is right?

[@ProfessorDaveExplains]

i guess if we get super technical, the latter sounds more rigorous of a definition to me, but sometimes it's easiest to just speak colloquially and bestow objects with potential energy and things like that. a physicist would probably offer better insight!

[@buscadores6657]

excuse me teacher how can you answer this question if you dont have all the values? where is the mass of the pasive object? are you just flattering or just Mad? now id like to see how to calculate 1.539 jules hitting an object with high mass lets say it hits a masive truck with no wheels. its an old and rusty truck with 45weight tns its just like a 45tons rock. whats the new velocity after the event?

[@user-qq5es3se6s]

Thanks ❤prof dave

[@leoyanshianliao6706]

Professor I think you forget to mention the relation of work with potential energy, I wonder if it’s work= change in potential energy

[@jessicagaffney4085]

Thank you!! very helpful!

[@angelitapinto9712]

i want this teacher to my school

[@albertocruz8992]

I have a question. In the part of the work-kinetic energy theorem, you said that when the work is negative, the system is doing a work, but in my opinion, the force is doing a work that makes that the kinetic energy of the particle decreases, and this work can be computed as the subtraction between final kinetic energy and initial kinetic energy of the system. What do you think?

[@carultch]

When net work is negative, this means work is leaving the kinetic energy of the object we are studying, and the object decreases its speed. This could mean energy is being stored in the form of potential energy, or it could mean a non-conservative force such as kinetic friction is converting the energy into heat and taking energy out of the mechanical domain. Potential energy is a shortcut to calculate the work done by conservative forces, because it is a state function instead of a path function. It only depends on initial and final states, rather than the details of the path. When we exclude forces associated with a potential energy, and only study the non-conservative forces, the work-energy theorem changes from "KEfinal = W + KEinitial" to "KEfinal + PEfinal = KEinitial + PEinitial + Wnc". The sum total of PE+KE is what we call the mechanical energy; i.e. the energy we can exchange reversibly through the mechanical actions of the system. Wnc is the work of non-conservative forces. Such as work done by human forces to initiate the energy of the system, or work dissipated as heat by frictional forces, or work done on a human as human forces guide the system to rest. Any force that can add or subtract energy to an object in motion, for which we don't track a potential energy.

[@ryankuykendall8303]

@@carultch Great explanation. I know you're responding to someone else but that's still very helpful for me, thanks xD!

[@carultch]

@@ryankuykendall8303 Always happy to help.

[@michdawnespera9578]

@@carultch so does that explain why 1539 is negative because it is leaving the Kinetic Energy of the object?

[@carultch]

@@michdawnespera9578 Yes. If kinetic energy is decreasing, that means the net work being done on the object is negative. Is there a specific issue I could help clarify, that I'm not seeing in your question?

[@derekanderson7854]

I don't understand how the gravitational potential energy can depend on height in this simple way. Suppose you take an object and increase its height by 100,000,000 kilometers; does such an object have more potential energy or less than an object at 10 meters above the ground? The object at 10m will experience much greater acceleration because the object at 100,000,000 km is so far away and thus experiences a much weaker gravitational field. Does the definition assume a uniform gravitational field throughout space?

[@zainulhassan-pk2nz]

Wow man you are great

[@kimfigueroa2914]

Since the start of online classes, some teachers are not at all efficient in explaining this. ARIGATO GOZAIMASU DAVE SENSEI!!!!!!😄

[@lindseyrosario1023]

Remember this

[@Osus_theDrifter]

this guy has saved us from at least 1 exam

[@mimidoomiraclegreatmiraclo2298]

Plz sir I so grateful for ur lesson and love it, it's more understandable. But plz sir can u illustrate ur calculation, I am finding it difficult to... Plz 🙏🙏🙏

[@monirferdouskhan3346]

Would someone please explain the difference in 'work done on a system' and work done by the system'??

[@sudiptachatterjee1610]

Can anyone tell me from where the 0.5 comes? I struggled to understand😢 4:10

[@davidkatuin4527]

I have an interest in kinetic energy and I am looking for a definition as we as an example. I also think it should be broken down and simplify. I know that a ball sitting on the ground still has kinetic energy.

[@carultch]

A ball sitting on the ground has zero macroscopic kinetic energy in the reference frame of the ground. If you look at it from a different reference frame, like the center of Earth, it will have kinetic energy as a consequence of moving with its immediate environment. It also has internal kinetic energy at the molecular level, as this is how objects store their thermal energy. Every object that isn't at absolute zero has internal kinetic energy.

[@smitshah8074]

thank you

[@syedanaveera1871]

As object go downwards the potential energy decreases, when it reaches the ground does it have potential energy? I mean there's no height covered left so p.e will be zero. Right?

[@ProfessorDaveExplains]

Yes, because we assign the ground as having zero potential energy. We set the axes ourselves.

[@ngathjwokesther5880]

I find it easy to watch your explanation than reading too much notes

[@ashfaqmahmudshovon9097]

As velocity is relative,Is kinetic energy relative?

[@ianjaypaullo1284]

Finally know the right answer now😊

[@iftakherwazid]

Is there any chance that Kinetic energy and Potential energy are equal at a height?

[@shanmugamv8815]

What if the other object's mass is greater

[@jeffwilken7241]

Delivery is quite stiff, but I love your format and exceptionally clear writing. Thanks for making this!

[@kelvinthehuman]

He sticks to rigor and he's fun yet which is rather a rare combination. Only someone gifted can do something similar. Saludos desde la República Domincana!

[@sumeetgupta169]

professor dave i should tell u this but u should had explain that kinectic energy as u did with potential energy . You explained the potential well but i ma bit confused in kinetic.

[@ProfessorDaveExplains]

it's the energy an object possesses by virtue of its motion, just like i explain here! you can email if you have a specific question.

[@MonCarlo]

does this mean that an object with a greater mass has more PE? if the object is at rest why must we still consider the mass of an object?

[@ProfessorDaveExplains]

more mass means more gravitational attraction between two bodies!

[@jeremycelis7489]

Why was the other mass canceled out??

[@VanityNutrition]

I'm a bit lost as to how you got rid of the kg value from Joules. Don't the +50.0 kg and -50.0 kg cancel each other out, leaving no kg to cancel the one from Joules?

[@ProfessorDaveExplains]

I multiplied both by the one half to get 25, and then I factored that 25 out of the difference so that it operates on that other term in brackets!

[@angeladoll2768]

Can someone please tell me that do all objects have potential energy?? I'm in 6th grade and it's an assignment which we've to submit the next week? Kindly help me! I'll be highly thankful!!

[@eviavlahos]

ur a legend

[@narayanidhar7899]

Professor Dave sir can you please describe the problem

[@zplymer]

FR BRO

[@jullianescubil3943]

How is it when you distribute m it become become 1/2mv ?. Is it because m has and invisible 1 and the denominator is 2 therefore it becomes 1/2. ? What algebra did you exactly use for this question. To arrive at W=1/2mvf^2-1/2mv^2. I understand the how m is distributed its the denominator and 1/2 values that are really confusing to me?

[@carultch]

The 1/2 and m are both constants, given the same object. We are interested in KE_final - KE_initial. We make two copies of the expression on the right side of the equation, KE=1/2*m*v^2, and we assign final and initial subscripts respectively. Since both terms have 1/2*m in common, and it is the same m in both cases (this is the salient point), we can factor that out in front, and just have (v_final^2 - v_initial^2) inside the parenthesis. Such that the expression becomes 1/2*m*(v_final^2 - v_initial^2). 1/2 obviously doesn't change between the two states, but m very well could change if there is a reason for it to change (like a rocket that loses mass after using its fuel)

[@frenchfried3731]

Ly man tysm

[@paulhughes1549]

I understand this except for the math at the end. I get why those values plug into the equation the way they do, and I know that joules is kg m^2 / s^2 in SI base units. After that I'm stuck - I can't see how the equation has been simplified and rearranged. Help please Prof. Dave! Loving your videos btw

[@ProfessorDaveExplains]

so first we just multiply 50 kg by 0.5 in both terms on the right side to get 25 kg, and then we factor 25 kg out of the binomial to get 25 kg times that reduced binomial then when we divide both sides by 25 kg we lose kg on the left, ending up with m^2/s^2, we add the other m^2/s^2 term from the right side, and when we take the square root its m/s! if this is still tricky, i suggest watching lots of my math tutorials!

[@paulhughes1549]

+Professor Dave Explains Thanks Professor Dave. It's a long time since I studied maths at school so I'm a bit rusty, so yeah I will have to watch some of your maths videos. (Yes "maths" with an s - that's how we say it here in the UK :) )

[@elangop8357]

thank you so much sir !! your videos are short and clear. initially I hated physics but after seeing your videos I got clarity about concepts . Your doing great job.

[@jievogarcia7206]

Why is work negative in the end?

[@habibaelhadad1000]

thank u

[@muhamedhameed5574]

this may be a european problem, but does the comma in he problem depict a decimal number or is that a thousand? because i have been confused by the answer for 10 minutes

[@advanced2780]

wow my pshyc teacher gave us link to here

[@nybaddies]

lol not my school showing this video for science-

[@elaafalmalek7401]

Why was the work negative?

[@robx9076]

Is it correct to say there is no potential energy. For example if you spin a stone which is tied with a string, a circle start to appear, but in reality it is not a circle. In other words instead of your eyes seeing colors reflecting out of the stone from a single point of your eye sight, they capture the color of the stone from different places. Now, try to apply it to an object that is not moving. The particles the object is made up of reflect light from relatively small places, but it doesn't mean that they are not moving. I think you can apply it to texture as well. As a matter of fact, I don't think objects have shapes. For example if a blind man touches a small square he can tell it is a square, but what if he were to touch a relatively very large square (think of a kilometers wide one.). Now, how on earth will it be possible for him to say it is a square, without experiencing the whole square(why don't you apply it to a ball). Why experiencing the whole object matters? Grab a small square and close your eyes...! When you grab that small square tight, what your hand can experience is different pressure values which come from different part of that object. What your hand does is get that values relatively and compare them to the values that you got when you first touched a square (Remember what your mother told you what you should call it when you first experience those relative pressures?). So, they is no shape, but there is pressure How about the shapes you see? Trust me it is even simpler. All you need are a chalk and blackboard. When you have not drawn anything on the board, do you see any shape? NO? Now, draw a circle using the chalk. So, how shapes come to existence without more than two colors and different color patterns. Again, there is no shapes, but there are colors (I know it is weird, and I would like to explain it more, if you agree above things)

[@ProfessorDaveExplains]

dude, i want whatever you're smoking!

[@robx9076]

:D

[@robx9076]

Do you like my UHC?

[@Deeeeeeeeeeeeeeeeeeeeeeeeez]

I wasn't careful enough so didn't take into consideration that W has to be negative. Just by the change of a sign I got my results = 13.674m/s. So just by the change of a sign I gained more energy after the impact x'D

[@juanit0tackit0tackito2]

How did you get 7.99 m/s? I got 13.67m/s… When I plug both answers in to find Joules (as to check) for 7.99 I get -1,539.99 j and for 13.67 I get 1,539 j Am I typing something in wrong?

[@domshot1238]

1:01 holy cow

[@thomasbastiansen8499]

"after some simplification" lol, still seems hard to me

[@edrozario5491]

Why is the work in the comprehension in negative value?

[@kiahmedallo9788]

"transfers" 1539 J energy to another object as work, so work is done "by" the system. Therefore, work has a negative value.

[@jonah5908]

Can someone provide a more in depth explanation? I made the same mistake, I input the value for W as a positive integer. Please explain?

[@catlife8064]

Nice

[@SailorJenova]

I wish I knew about you when I had to take Intro to Physics like 2 years ago. I would've gotten an A NOT a B! :( Oh, well ....understanding it is more important than a grade.

[@sayandkr4333]

Grades follow

[@dhruvverma6460]

@@sayandkr4333 grades relegates. It's just a number after-all

[@FieldMarshalYT]

Imagine being upset about a B.

[@hunzalashahid4000]

@@FieldMarshalYT imagine being super relieved cuz you passed the subject with a D XD.

[@FieldMarshalYT]

@@hunzalashahid4000 I can relate

[@kuiizoo]

i am only in 6th grade pls help :( my teacher set homework to do and we had to watch this video and I now have to write a 3 page essay about kinetic and potential energy but the video rlly helped :)

[@hersheychocolate7542]

oh my, how did it go. I’m in 8th having to take notes.

[@hafsaimtiaz5832]

In exmple y do uh assume works = -1539 kg