Talk:Work (physics)

Wiki Education assignment: 4A Wikipedia Assignment

This article was the subject of a Wiki Education Foundation-supported course assignment, between 21 August 2023 and 16 December 2023. Further details are available on the course page. Student editor(s): ThomasDLV, DiabeticPigeon (article contribs). Peer reviewers: Djoung, Alana1132.

— Assignment last updated by Kmijares (talk) 22:40, 15 November 2023 (UTC)

No experimental evidence for the claims made

We cite sources, not primary experiments.

The second paragraph provides an example for which I claim there is no verifying experimental evidence. Gravity provides a force of 9.8 meters of velocity per every "one" second (that's what Newton actually said.) Galileo proved that in one unit of time you get one unit of distance and in two units of time you get four units of distance (1 3 5 7....) Four units of distance is only two units of time and only two units of applied force. Please Link me to physical experimental evidence that four times the height produces four times the work done in watts/joules or concede the paragraph is junk physics and needs revision. Here is the text of the paragraph in question: For example, when a ball is held above the ground and then dropped, the work done by the gravitational force on the ball as it falls is positive, and is equal to the weight of the ball (a force) multiplied by the distance to the ground (a displacement). If the ball is thrown upwards, the work done by the gravitational force is negative, and is equal to the weight multiplied by the displacement in the upwards direction. Draft Physics (talk) 04:32, 17 February 2024 (UTC) You will need a citation for that claim from Galileo DrPhysics999 (talk) 05:29, 17 February 2024 (UTC) https://www.google.com/search?q=1+3+5+7.+galileo+galilei&sca_esv=17a68768bff6222b&hl=en&source=hp&ei=BUXQZY3zENPaptQPxp6ouA8&iflsig=ANes7DEAAAAAZdBTFaRP3FiORhvTAJfoD8Yn_9lrEZoz&oq=1+3+5+7.+gali&gs_lp=Egdnd3Mtd2l6Ig0xIDMgNSA3LiBnYWxpKgIIAjIFECEYoAEyBRAhGKABMgUQIRigATIFECEYoAFIo4MBUABY02JwAHgAkAEAmAFooAHAA6oBAzUuMbgBAcgBAPgBAvgBAcICBhAAGBYYHsICBRAhGJ8F&sclient=gws-wiz Draft Physics (talk) 05:34, 17 February 2024 (UTC) Which isn’t “ one unit of time you get one unit of distance and in two units of time you get four units of distance” DrPhysics999 (talk) 06:23, 17 February 2024 (UTC) I'm sorry if you misunderstand. It's just an absolute fact that in one unit of time you fall one unit of distance. In two units of time you fall four units of distance. In three units of time you fall nine units of distance.... Four units of distance is only two units of time. And therefore you only receive two units of a 9.8 meter increase in your velocity. Four units of distance only gets you 19.6 meters per second of total velocity. Four units of distance is just two units of time just two units of velocity and just two units of weight. Draft Physics (talk) 06:31, 17 February 2024 (UTC) The proof is found here https://en.m.wikipedia.org/wiki/Galileo%27s_law_of_odd_numbers which conflicts with your statement that “ Galileo proved that in one unit of time you get one unit of distance and in two units of time you get four units of distance” remember 1/2at^2 DrPhysics999 (talk) 06:28, 17 February 2024 (UTC) We apparently have an unreconcilable difference in understanding vocabulary. Nothing I said is inconsistent with what Galileo stated. You're creating a completely false conflict. Draft Physics (talk) 06:33, 17 February 2024 (UTC) Would stating 1 + 3 = 4 help Draft Physics (talk) 06:37, 17 February 2024 (UTC) https://physics.stackexchange.com/questions/482822/galileos-law-of-odd-numbers Here is another proof of Galileo’s Law of Odd Numbers using 1/2 at^2 DrPhysics999 (talk) 06:37, 17 February 2024 (UTC) That made up story has nothing to do with the facts I stated. Again there is no conflict. you haven't proven my statements inaccurate. If you're going to state that I made an error quote the sentence you say is unacceptably fallacious. Draft Physics (talk) 06:56, 17 February 2024 (UTC) Yes. Your error is that you think 1/2at^2 isn’t correct to describe the law of odd numbers. DrPhysics999 (talk) 07:01, 17 February 2024 (UTC) Your error is putting the cart before the horses. Time controls distance, distance doesn't control time. Draft Physics (talk) 10:49, 17 February 2024 (UTC) So you say without any experimental evidence. DrPhysics999 (talk) 15:14, 17 February 2024 (UTC) So you say without any experimental evidence. The standard hypocrisy and duplicity. You don't have to have evidence but anyone arguing something else does. Fair cop not. You've had 300 years, Millions of scientists, and billions of dollars to prove it takes 25 times to fuel to go five times as fast and yet you can cite nothing. Draft Physics (talk) 15:56, 17 February 2024 (UTC) Just think about. If you are in free fall you are accelerating and for every unit you might have a unit of distance at first but that is not correct as you keep speeding up. DrPhysics999 (talk) 07:32, 17 February 2024 (UTC) Just think about. I've spent 10 years thinking about it If you are in free fall you are accelerating and for every unit you might have a unit of distance at first but that is not correct as you keep speeding up. Gravitational acceleration is no different than collecting spray paint... The longer you're in the spray (free falling) the more paint you collect. Draft Physics (talk) 10:55, 17 February 2024 (UTC) Gravitational acceleration is no different than collecting spray paint... The longer you're in the spray (free falling) the more paint you collect. So why does a baseball lose velocity when you throw it upwards? Your analogy falls apart upon the simplest scrutiny. Selbram (talk) 14:43, 17 February 2024 (UTC) Again you're just trolling.... When you go with the Stream you go faster when you go against the stream you go slower. Draft Physics (talk) 15:09, 17 February 2024 (UTC) So to defend your analogy, you completely change your analogy. Does the baseball collect more paint or not in your paint analogy? It clearly does not, which means my post was correct in calling you out. I am pointing out the inadequacies of your statements and providing counterarguments. Selbram (talk) 15:15, 17 February 2024 (UTC) You are going to spend a lot more time stuck on this. DrPhysics999 (talk) 15:15, 17 February 2024 (UTC) Before you bail on the conversation would you please just answer one question. The math says it takes 25 times the fuel/energy to spin a motor five times as fast. Do you honestly think that is the truth? Draft Physics (talk) 15:47, 17 February 2024 (UTC) Here's an actual quote by Galileo: "The spaces described by a body falling from rest with a uniformly accelerated motion are to each other as the squares of the time-intervals employed in traversing these distances." It's Theorem II, Proposition II of page 174 in https://www.google.com/books/edition/Dialogues_Concerning_Two_New_Sciences/WNMPAQAAMAAJ?hl=en&gbpv=1&pg=PA174&printsec=frontcover Selbram (talk) 08:56, 17 February 2024 (UTC) "The spaces described by a body falling from rest with a uniformly accelerated motion are to each other as the squares of the time-intervals employed in traversing these distances." Again there is no inconsistency. Galileo is saying time determines distance. You can pretend the distance made the time happen but the fact is the time made the distance happen. The more basic fact is four times the distance only twice the time, only twice the velocity, only twice the weight, and only twice the force. Draft Physics (talk) 10:59, 17 February 2024 (UTC) First off, bold text doesn't make you anymore less wrong or less confused than you already are. Second, I never said "distance made the time happen" (whatever that could even possibly mean), so you are invoking a strawman. To say "time made distance" or "distance made time" is nonsensical gibberish. The fact is, the distance traveled by a freefalling object vertically down is proportional to the square of the time elapsed, hence the correct formula is d = 1/2*a*t^2. If you agree with that, then, great, there is no problem here. If you disagree, then you are disagreeing with basic kinematics as described by Galileo. I hope that helps. Selbram (talk) 13:49, 17 February 2024 (UTC) First off, bold text doesn't make you anymore less wrong or less confused than you already are. Clearly the Bold text is just to enhance readability ...you're just trolling Second, I never said "distance made the time happen" (whatever that could even possibly mean), so you are invoking a strawman. If Galileo thought 4.9 meters of distance caused 9.8 velocity he would have said so... He didn't so there is no straw man To say "time made distance" or "distance made time" is nonsensical gibberish. The entire argument is about the cause of the effect... Does velocity come in units of time or in units of distance. Galileo and Newton obviously thought it was units of time. The fact is, the distance traveled by a freefalling object vertically down is proportional to the square of the time elapsed, Demonstrating the point that time is in control hence the correct formula is d = 1/2*a*t^2. Doesn't change the fact that four units of distance is not four units of force If you agree with that, then, great, there is no problem here. Why would I agree with unevidenced nonsense If you disagree, then you are disagreeing with basic kinematics as described by Galileo. You're just slandering Newton descartes and Galileo Draft Physics (talk) 14:19, 17 February 2024 (UTC) Second, I never said "distance made the time happen" (whatever that could even possibly mean), so you are invoking a strawman. If Galileo thought 4.9 meters of distance caused 9.8 velocity he would have said so... He didn't so there is no straw man What in the world are you even saying?! Distance does not cause velocity. It cannot cause velocity. Distance is a description. The idea that if he thought something, he would have said it is another unreasoned claim. But this all irrelevant because no one is claiming distance cases anything. To say "time made distance" or "distance made time" is nonsensical gibberish. The entire argument is about the cause of the effect... Does velocity come in units of time or in units of distance. Galileo and Newton obviously thought it was units of time. Velocity is not in units of time nor in units or distance. Velocity comes in units of distance per time. In SI units, it is meters per seconds. Your claim about what Galileo and Newton thought has no weight whatsoever. The fact is, the distance traveled by a freefalling object vertically down is proportional to the square of the time elapsed, Demonstrating the point that time is in control Setting aside whether, "time is in control" or not, or if that even makes any sense, if you agree with my comment, then it follows that d ∝ t^2. hence the correct formula is d = 1/2*a*t^2. Doesn't change the fact that four units of distance is not four units of force This is a complete nonsensical non-sequitur. Do you agree that the correct formula is d = 1/2*a*t^2 or not? I said nothing, absolutely nothing, about relating units of distance to units of force. Please, stay on the topic. If you agree with that, then, great, there is no problem here. Why would I agree with unevidenced nonsense If you disagree, then you are disagreeing with basic kinematics as described by Galileo. You're just slandering Newton descartes and Galileo So you don't disagree that d = 1/2*a*t^2 (because you would have said it was wrong when you had the chance), but now you do disagree? Can you please be consistent. You are not being logical whatsoever. And your claims about Newton, Descartes, and Galileo have no weight considering how you cannot even follow the conversation. Stop attempting to name-drop and stick to the discussion. Selbram (talk) 14:34, 17 February 2024 (UTC) You're obviously the one not on the subject. The web page States that something falling in gravity collects force in units of distance. That if something Falls 4 units of distance it will collect four units of work/energy. I've clearly stated there is no physical experimental evidence demonstrating this to be true. Four times the distance is only twice the time, twice the velocity, and twice the weight / momentum. Draft Physics (talk) 14:55, 17 February 2024 (UTC) You brought up the discussion of the relationship between time and distance (and yet you cannot even answer a simple question about whether a basic kinematic formula is correct or not). Not me. If we cannot agree on kinematics (which again I repeat myself: you brought this up), then we cannot advance to higher level topics. Selbram (talk) 15:00, 17 February 2024 (UTC) The quoted text For example, when a ball is held ... upwards direction looks like my wording (see my edit 2022/10/19). I have just read it again and it looks good. I continue to stand by the content of the paragraph. On Wikipedia we don’t support the content with experimental evidence - for support we quote reliable published sources. The content of this article, including the paragraph in question, is well supported by reliable published sources. The paragraph in question contains information that will be found in any good physics textbook covering the topic of classical mechanics. Draft Physics has written some text that is never going to be supported by a reliable published source: ”Gravity provides a force of 9.8 meters of velocity per every one second...” ”Galileo proved that in one unit of time you get one unit of distance ...” ”In two units of time you get four units of distance...” ”Four units of distance is only two units of time and only two units of applied force.” It looks like Draft Physics has read a bit of kinematics but hasn’t yet moved onwards to kinetics and mechanics. I suggest Draft Physics get hold of one of those good physics textbooks and begin reading. Dolphin (t) 06:42, 17 February 2024 (UTC) Stating your Dogma doesn't have to be supported by evidence pretty much proves my point. There is no scientific process without supporting evidence. What differentiates science from religion is evidence. Either physical experiments or very good maybe even irrefutable, reasoning. I believe Galileo provided irrefutable physical evidence, and an honest reading of Newton provides irrefutable logical evidence. You're claiming you don't have to prove your science with evidence. So we all must believe it takes 100 times of fuel to go 10 times as fast the fact that it isn't true doesn't matter to you? Draft Physics (talk) 06:52, 17 February 2024 (UTC) Here is another proof of Galileo’s law of odd numbers using 1/2at^2 https://manifold.umn.edu/read/untitled-7ca18210-217d-40f2-83fe-b0add1d84ede/section/bb88e7f4-7451-4b26-9056-a21f51f49091 DrPhysics999 (talk) 06:55, 17 February 2024 (UTC) These are the consequential predictions of the mathematical formulation. They appear flat Earth ridiculous to me, and I certainly claim they have never been proven by experiment or good logic. Four times the fuel to spin A motor twice as fast Nine times the fuel to spin A motor three times as fast 16 times the fuel to spin A motor four times as fast 25 times the fuel to spin A motor five times as fast ... 100 times the fuel to spin A motor 10 times as fast 10,000 times the fuel to spin A motor a hundred times as fast Draft Physics (talk) 11:13, 17 February 2024 (UTC) Do you accept that distance = 1/2*a*t^2 or not? This is a simple question you should be able to answer without invoking other stuff. Selbram (talk) 13:53, 17 February 2024 (UTC) The counter question would be do you believe 4.9m of distance creates 9.8 meters/s of increased velocity. Do you believe that every time something travels 4.9m in free fall it gains another 9.8 m/s of velocity. The formula being argued is W (energy) = F x D. Nowhere have I stated or implied that I do not believe the distance you will travel in free fall is the square of the time you are allowed to fall. Your question is a straw man. Draft Physics (talk) 14:29, 17 February 2024 (UTC) Stop evading and answer the question: Do you accept that distance = 1/2*a*t^2 or not? Selbram (talk) 14:35, 17 February 2024 (UTC) As I clearly stated: Nowhere have I stated or implied that I do not believe the distance you will travel in free fall is the square of the time you are allowed to fall. Your question is a straw man. You are clearly just trolling Draft Physics (talk) 14:45, 17 February 2024 (UTC) I am asking for clarification. If you agree, you can just say yes. If not, you can just say no. This is not a trick question. It is as straightforward as it can be. Also, a question cannot be a strawman. A strawman is a proposition (that is true or false) that mischaracterizes what someone thinks or says. A question cannot be true or false, so it fails to meet the definition of a strawman. Again, you are evading. I am trying to get clear feedback from you (given that you seemed to brought up this subtopic in the first place). Selbram (talk) 14:49, 17 February 2024 (UTC) If you're going to keep trolling I'm not going to reply to your comments, you're wasting my time. I've clearly stated my position and it's clearly consistent with Newton's and Galileo's position. The fact that Free Falling causes you to move distance does not mean that the distance caused you to fall. The force of gravity comes in 9.8 Meter per one second units. That is the Galilean fact you are perverting. Draft Physics (talk) 15:00, 17 February 2024 (UTC) I've clearly stated my position And yet you cannot answer whether d = 1/2*a*t^2, which you started arguing over. You are being incredibly evasive and ambiguous about it. "The fact that Free Falling causes you to move distance does not mean that the distance caused you to fall." Let me repeat myself yet again: I never said or even implied that. You are completely The force of gravity comes in 9.8 Meter per one second units. No, force comes in units of Newtons. It causes an acceleration of 9.8 m/s (velocity) per second (time). And again, your name-drops hold absolutely no weight. You saying, "you are perverting Galileo" doesn't make you any more correct or justified. If you are going to make such a claim, you back it up. So far you fail to do even the most basic task. Selbram (talk) 15:08, 17 February 2024 (UTC) Let me be absolutely clear: When DrPhysics999 said, "Here is another proof of Galileo’s Law of Odd Numbers using 1/2 at^2" you started arguing about it. So it stands to ask, do you agree with the formula or not? You are not being clear on this matter, and so far you refuse to be clear. Selbram (talk) 14:53, 17 February 2024 (UTC) That formula just states that you travel 4.9 distance to gain 9.8m/s of velocity but it's obviously only true in the first second. In the second second you travel and added 14.7 Meters but still only collect 9.8 Meters per second of added velocity. Draft Physics (talk) 15:06, 17 February 2024 (UTC) That formula just states that you travel 4.9 distance to gain 9.8m/s of velocity but it's obviously only true in the first second. Okay, so you finally give a partial answer. For some reason, you only consider the first and second seconds. Is it true for all times (in an idealized case)? If you plug t = 2 s and g = 9.8 m/s^2 into d = 1/2*g*t^2, you obtain d = 19.6 m, which is consistent with 4.9+14.7 meters. Selbram (talk) 15:12, 17 February 2024 (UTC) I really don't have much use for this semantics game. The fact that four times the distance is four times the distance doesn't need to be argued. My claim is you have no physical evidence four times the distance is four times the energy in free fall. I say again four times the distance is only twice the time, it is only twice the velocity, and it is only twice the weight/pressure/energy/Force. 74.105.245.94 (talk) 15:34, 17 February 2024 (UTC) I am assuming you are Draft Physics. I really don't have much use for this semantics game. So then why couldn't you have just answered the question (to which you still only answered partially)? If you just did, it would have made things much easier for both of us. The fact that four times the distance is four times the distance doesn't need to be argued. That is definitely not what is being argued. We are arguing about whether you accept a formula that describes a relationship between time and distance (for an idealized free-fall). My claim is you have no physical evidence four times the distance is four times the energy in free fall. I say again four times the distance is only twice the time, it is only twice the velocity, and it is only twice the weight/pressure/energy/Force. Ok, well an object traveling 4 units of distance cannot make it twice the weight. Depending on which definition you use of weight, either the weight stays constant (because the force of gravity is always m*g applied to you) or the weight is 0 (because there is no pressure applied to you in free-fall). When it comes to pressure, it is unclear what you are referring to. Pressure between which two things? When you say twice the energy, I'd like to see you define energy, because it appears you are not using the same definition as the conventional definition. In order to proceed in this conversation, we need to has out our notions. As for force, when something is in an idealized free-fall, the only force involved is the force of gravity (F = m*g), which stays constant. If it didn't, then acceleration wouldn't be constant for free-fall. Selbram (talk) 15:47, 17 February 2024 (UTC) The example given involves a ball falling or being thrown upwards but the definition of work is not confined to free fall - the statement is equally valid when slow motion at constant speed is involved. Let me illustrate with a question and answer. Q: An old man carries a suitcase up a flight of stairs from ground level to a level 15 metres above ground. If the suitcase weighs 100 newtons, what work is done by the force of gravity (the weight) acting on the suitcase? A:The force is 100 N and the displacement is 15 m. The two act in opposite directions so one is positive and the other is negative; therefore the work done is negative. The answer is -1500 N.m (or 1500 N.m of negative work.) The answer can also be given as -1500 joules (or 1500 joules of negative work.) The acceleration of an object, or the distance it travels in 1, 2 or 3 units of time, is entirely irrelevant in the matter of the work done. The work done on an object by the force of gravity on that object has significance: If multiplied by -1 to change its sign, it is the change in the gravitational potential energy of the object. In the above example of the suitcase, its gravitational potential energy increased by 1500 joules as the consequence of the work done on it by its own weight. Dolphin (t) 14:22, 17 February 2024 (UTC) Q: An old man carries a suitcase up a flight of stairs from ground level to a level 15 metres above ground. If the suitcase weighs 100 newtons, what work is done by the force of gravity (the weight) acting on the suitcase? I could counter this example by simply stating if a weightlifter slowly lifts a weight he will do a lot more work then if he lifts it quickly. The faster you move something through gravity the less work you will have to do. NASA will tell you so. A:The force is 100 N and the displacement is 15 m. And you're going to travel that displacement over a much larger amount of time obligating you to fight more gravity and do more work. The two act in opposite directions so one is positive and the other is negative; therefore the work done is negative. The answer is -1500 N.m (or 1500 N.m of negative work.) That would be the answer in freefall not the answer in slow lift The answer can also be given as -1500 joules (or 1500 joules of negative work.) Can you cite any experimental evidence where the jewels of energy are measured? The acceleration of an object, or the distance it travels in 1, 2 or 3 units of time, is entirely irrelevant in the matter of the work done. Obviously I contend the opposite is true and I claim in 300 years you have produced no physical experimental evidence that it takes 25 times the fuel to go five times as fast. The work done on an object by the force of gravity on that object has significance - if multiplied by -1 to change its sign, it is the change in the gravitational potential energy of the object. In the above example of the suitcase, its gravitational potential energy increased by 1500 joules as the consequence of the work done on it by its own weight. If you take 10 times the time to lift a weight you will do 10 times the work I claim that is the actual fact. Draft Physics (talk) 14:43, 17 February 2024 (UTC) Please make a video about how pisst off you are so we can use it as a reference on the work Wikipedia page. DrPhysics999 (talk) 15:50, 17 February 2024 (UTC) I'd rather you make the public statement that you actually believe it takes 100 times the fuel to spin a motor 10 times as fast. That should be a reference on the work page of wikifables. Draft Physics (talk) 16:01, 17 February 2024 (UTC)

dot product

When the work is first defined, the part that says:

then the work done is given by:

W = F s cos(θ)

Shouldn't it be the lengths of F and s instead of just plain F and s? 24.232.240.207 (talk) 05:48, 14 April 2024 (UTC)