Capiert Posted January 15, 2023 Posted January 15, 2023 This (thread) is (about) a (syntax(_bias)) complaint. There are several kinds of KE; but only 1 is acknowledged. What does it mean to set the Kinetic_Energy(_difference)'s (KEd=m*(vf2-vi2)/2) initial_speed vi=0 to zero? KEd=m*(vf2-0)/2. (?) (I mean..) If the Kinetic_Energy(_difference) KEd=(m*vf2/2)-(m*vi2/2) is the 1st term, the final_kinetic_energy KEf=m*vf2/2 minus the 2nd term, the initial_kinetic_energy KEi=m*vi2/2 as, KEd=KEf-KEi & the initial_kinetic_energy KEi=m*02/2=0 is (assumed) zero, then we can only have the final_Kinetic_Energy KEf=KEi+KEd KEf=0+KEd or (when swapping, the sequence order) KEf=KEd+0 which "might" appear as (the_same=) identical (when it is NOT always (identical) e.g. when initial_speed vi#0 & initial_kinetic_Energy KEi#0 are NOT zero). Thus (we or) I must ask (what they ((term_names) really) are (representing)) e.g. what is the final_Kinetic_Energy KEf?; & what is the initial_Kinetic_Energy KEi?; & what is the Kinetic_Energy(_difference) KEd? It seems (to me, (that)) physicists are (absolutely) completely (=100%) confident that the Kinetic_Energy_"difference" KEd=KEf-KEi is NOT "The(e)" (=their) Kinetic_Energy KEf-0 because (perhaps (the) subscripts are (or were) missing?) although both are (a kind of) (kinetic_)Energy. (But differentiation, is a "difference" method (adding the series (of differences).) (Why the restriction to only 1 kind of KE when there are several (kinds)?) (E.g. (Oh) "KE"(?), we worship (only) "Thee"! (?) :-) (But which 1?) (Kinetic is (=implies) "motion", thus KE is motion_energy.) Why do they (physicists) bother splitting hairs** (just to be different)? (**E.g. Tending to ONLY 1 kind, of=from several. Preferring ONLY the KE_difference, (when=)with its initial_speed vi (is) set to zero.) (I mean) (Because..(it seems to me, that)) the Kinetic_Energy "difference" KEd is "the" most "general"*** definition of Kinetic_Energy; & setting its initial_speed vi=0 is (but) "only 1" (specific) example (of Kinetic_energies, =motion_energies) from many (examples). (*** I'( ha)ve stated that, in other threads before; 1. Energy is suppose to (be accountable, &) add if it can NOT be created, NOR destroyed; 2. but it does NOT always (add (up)), 3. although KEd is (already) relative. Now including the subscript d=difference (syntax).) Thus, how can (you or) those physicists (possibly) suppose that: the final_Kinetic_Energy KEf (but) minus the initial_Kinetic_Energy KEi (by letting vi=0) is (suppose to be) "the(e)" ONLY Kinetic_Energy KE? (=KEd)= KEf- (KEi=0) ((possible) that exists, & is correct (only) so)? [That seems to me rather "narrow_minded", or misled. E.g. 1 Person's (restriction_)ERROR, & then everybody jumps on the (same) bandwagon (without thinking). E.g. NOT quite knowing what you are talking about. =] DON'T you think that'( i)s a little bit narrow_minded? Or misled? E.g. NOT (quite) the full story. Or am I wrong? & if so why?, etc. E.g. Science confirms itself. There are many ways (to Rome=roam). Disclaimer: That was (more, or less) my complaint about (an) inconsistent syntax (bias) in physics. I DON'T claim to be perfect (either), & (I (also) have to make (syntax) compromises (e.g. preferences) (in order, for them (compromises)) to remain recognizable (at least a bit). Physics is a straight jacket, as Feynman would say. For those who DON'T know: "Straight" actually (is) implying, too rigid (e.g. &/"or") (for the lunatics). Take it (=&/"or", leave it) either way you want. It's crazy. I hope I'm NOT being too impolite; & can drop the wool from your (biased) eyes. (I'm biased too, but differently.) (This is the time=Period of revolution, & we (=fat Victor & Co) are revolting.-Victor Buno. :-) Why prefer initial_speed zero? Einstein said NO (reference_)frame is preferred; but that is NOT true. There are advantages to some; or at least that is what you are implying=inferring. E.g. (A mass m, on Earth, with) vi=0 seems static but it is really (moving) at the same(=identical) speed (as the reference_frame, i.e. wrt Earth). (& we know the Earth is rotating, e.g. moving.) Thus (initial_)speed vi is "inherent". It (=vi) (when zero) is invisible to the (reference_)frame. (E.g. Zero is =NOTHING, 0 [m/s]. But) I can NOT imagine anything that is NOT moving (wrt the universe). & even the universe must be moving wrt some_thing.
exchemist Posted January 15, 2023 Posted January 15, 2023 7 minutes ago, Capiert said: This (thread) is (about) a (syntax(_bias)) complaint. There are several kinds of KE; but only 1 is acknowledged. What does it mean to set the Kinetic_Energy(_difference)'s (KEd=m*(vf2-vi2)/2) initial_speed vi=0 to zero? KEd=m*(vf2-0)/2. (?) (I mean..) If the Kinetic_Energy(_difference) KEd=(m*vf2/2)-(m*vi2/2) is the 1st term, the final_kinetic_energy KEf=m*vf2/2 minus the 2nd term, the initial_kinetic_energy KEi=m*vi2/2 as, KEd=KEf-KEi & the initial_kinetic_energy KEi=m*02/2=0 is (assumed) zero, then we can only have the final_Kinetic_Energy KEf=KEi+KEd KEf=0+KEd or (when swapping, the sequence order) KEf=KEd+0 which "might" appear as (the_same=) identical (when it is NOT always (identical) e.g. when initial_speed vi#0 & initial_kinetic_Energy KEi#0 are NOT zero). Thus (we or) I must ask (what they ((term_names) really) are (representing)) e.g. what is the final_Kinetic_Energy KEf?; & what is the initial_Kinetic_Energy KEi?; & what is the Kinetic_Energy(_difference) KEd? It seems (to me, (that)) physicists are (absolutely) completely (=100%) confident that the Kinetic_Energy_"difference" KEd=KEf-KEi is NOT "The(e)" (=their) Kinetic_Energy KEf-0 because (perhaps (the) subscripts are (or were) missing?) although both are (a kind of) (kinetic_)Energy. (But differentiation, is a "difference" method (adding the series (of differences).) (Why the restriction to only 1 kind of KE when there are several (kinds)?) (E.g. (Oh) "KE"(?), we worship (only) "Thee"! (?) (But which 1?) (Kinetic is (=implies) "motion", thus KE is motion_energy.) Why do they (physicists) bother splitting hairs** (just to be different)? (**E.g. Tending to ONLY 1 kind, of=from several. Preferring ONLY the KE_difference, (when=)with its initial_speed vi (is) set to zero.) (I mean) (Because..(it seems to me, that)) the Kinetic_Energy "difference" KEd is "the" most "general"*** definition of Kinetic_Energy; & setting its initial_speed vi=0 is (but) "only 1" (specific) example (of Kinetic_energies, =motion_energies) from many (examples). (*** I'( ha)ve stated that, in other threads before; 1. Energy is suppose to (be accountable, &) add if it can NOT be created, NOR destroyed; 2. but it does NOT always (add (up)), 3. although KEd is (already) relative. Now including the subscript d=difference (syntax).) Thus, how can (you or) those physicists (possibly) suppose that: the final_Kinetic_Energy KEf (but) minus the initial_Kinetic_Energy KEi (by letting vi=0) is (suppose to be) "the(e)" ONLY Kinetic_Energy KE? (=KEd)= KEf- (KEi=0) ((possible) that exists, & is correct (only) so)? [That seems to me rather "narrow_minded", or misled. E.g. 1 Person's (restriction_)ERROR, & then everybody jumps on the (same) bandwagon (without thinking). E.g. NOT quite knowing what you are talking about. =] DON'T you think that'( i)s a little bit narrow_minded? Or misled? E.g. NOT (quite) the full story. Or am I wrong? & if so why?, etc. E.g. Science confirms itself. There are many ways (to Rome=roam). Disclaimer: That was (more, or less) my complaint about (an) inconsistent syntax (bias) in physics. I DON'T claim to be perfect (either), & (I (also) have to make (syntax) compromises (e.g. preferences) (in order, for them (compromises)) to remain recognizable (at least a bit). Physics is a straight jacket, as Feynman would say. For those who DON'T know: "Straight" actually (is) implying, too rigid (e.g. &/"or") (for the lunatics). Take it (=&/"or", leave it) either way you want. It's crazy. I hope I'm NOT being too impolite; & can drop the wool from your (biased) eyes. (I'm biased too, but differently.) (This is the time=Period of revolution, & we (=fat Victor & Co) are revolting.-Victor Buno. Why prefer initial_speed zero? Einstein said NO (reference_)frame is preferred; but that is NOT true. There are advantages to some; or at least that is what you are implying=inferring. E.g. (A mass m, on Earth, with) vi=0 seems static but it is really (moving) at the same(=identical) speed (as the reference_frame, i.e. wrt Earth). (& we know the Earth is rotating, e.g. moving.) Thus (initial_)speed vi is "inherent". It (=vi) (when zero) is invisible to the (reference_)frame. (E.g. Zero is =NOTHING, 0 [m/s]. But) I can NOT imagine anything that is NOT moving (wrt the universe). & even the universe must be moving wrt some_thing. Yes, well, kinetic energy has to be specified with respect to a frame of reference, because velocity is relative. Why can't you post in normal length lines? This style is very exhausting to read. It makes one question whether it is worth the trouble.
Capiert Posted January 15, 2023 Author Posted January 15, 2023 (edited) 1 hour ago, exchemist said: Yes, well, kinetic energy has to be specified with respect to a frame of reference, because velocity is relative. I find that a good answer. It implies admitting ~1/2 the problem. But DON'T you think that (reference frame) need has been created artificially, by negating the initial_speed vi to zero? Now you have to suffer the consequences & are happy with it(s complexity). 1 hour ago, exchemist said: Why can't you post in normal length lines? This style helps me reduce my errors, which otherwise would then be "more" confusing to you. It helps me find subtle problems. 1 hour ago, exchemist said: This style is very exhausting to read. Sorry, (1st draft, needs maybe a 5th re_edit?) that's my handicap. It's a construct, e.g. programmed. Intended to read with natural pauses almost automatically; but sometimes it has to be broken down more (e.g. bracketed, (is (superfluous &) put) to the right end, (thus) ignorable) but gets messy. Me (when) against many (must be perfect, but isn't). It takes a lot of backbone to go "against" mainstream (errors?). (Sometimes) It's difficult to (get=) crystalize the ideas in order to (quickly?) pinpoint the problems; instead of make new 1's. I write more naturally when I feel uninhibited. Swansont will say there are NO errors in physics; only me, but sorry I DON'T believe him on some things (yet). 1 hour ago, exchemist said: It makes one question whether it is worth the trouble. It's pointing at a serious problem. Prejudice (bias), & ignorance of it. Please DON'T bother. It's intended to hedge (=prevent) future problems (conflicts). It'( ha)s obviously failed for now. I DON'T like it either. Stressy bad weather. Edited January 15, 2023 by Capiert
swansont Posted January 15, 2023 Posted January 15, 2023 4 hours ago, Capiert said: This (thread) is (about) a (syntax(_bias)) complaint. There are several kinds of KE; but only 1 is acknowledged. What other “kinds” of KE are there? I only know of the “kind” that is given by 1/2 mv^2 It can be applied to different particles and be measured/calculated at different times (hence you have initial and final as two common times) 3 hours ago, Capiert said: But DON'T you think that (reference frame) need has been created artificially, by negating the initial_speed vi to zero? Reference frames are incredibly useful for those that actually solve physics problems. 4 hours ago, Capiert said: the Kinetic_Energy "difference" KEd is "the" most "general"*** definition of Kinetic_Energy; No. the difference in kinetic energy represents the change in kinetic energy at two different points in time. It is not a definition of KE.
exchemist Posted January 15, 2023 Posted January 15, 2023 3 hours ago, Capiert said: I find that a good answer. It implies admitting ~1/2 the problem. But DON'T you think that (reference frame) need has been created artificially, by negating the initial_speed vi to zero? Now you have to suffer the consequences & are happy with it(s complexity). This style helps me reduce my errors, which otherwise would then be "more" confusing to you. It helps me find subtle problems. Sorry, (1st draft, needs maybe a 5th re_edit?) that's my handicap. It's a construct, e.g. programmed. Intended to read with natural pauses almost automatically; but sometimes it has to be broken down more (e.g. bracketed, (is (superfluous &) put) to the right end, (thus) ignorable) but gets messy. Me (when) against many (must be perfect, but isn't). It takes a lot of backbone to go "against" mainstream (errors?). (Sometimes) It's difficult to (get=) crystalize the ideas in order to (quickly?) pinpoint the problems; instead of make new 1's. I write more naturally when I feel uninhibited. Swansont will say there are NO errors in physics; only me, but sorry I DON'T believe him on some things (yet). It's pointing at a serious problem. Prejudice (bias), & ignorance of it. Please DON'T bother. It's intended to hedge (=prevent) future problems (conflicts). It'( ha)s obviously failed for now. I DON'T like it either. Stressy bad weather. Sorry, I really can't be bothered to wade through all this, er, stuff. Format it properly or I'm out.
Endy0816 Posted January 15, 2023 Posted January 15, 2023 Saying some mass went from 0mph to 60mph is just simpler than saying it went from 30mph to 90mph. Velocity value is basically arbitrary, as long as you are consistent about things. If I'm measuring my velocity as zero relative to myself, I can't tell the cop that pulled me over for speeding that I'm also going zero relative to the road. That doesn't work.
swansont Posted January 15, 2023 Posted January 15, 2023 5 minutes ago, Endy0816 said: Saying some mass went from 0mph to 60mph is just simpler than saying it went from 30mph to 90mph. In most cases. But the underlying principle is that you will get the same physics result, regardless of your choice of frame of reference.
Mordred Posted January 15, 2023 Posted January 15, 2023 1 hour ago, exchemist said: Sorry, I really can't be bothered to wade through all this, er, stuff. Format it properly or I'm out. I agree @Capiertthere is absolutely no reason to have a few words on each line it makes your posts look like bad poetry please fill in the lines so everyone can actually follow what you are posting
Lorentz Jr Posted January 15, 2023 Posted January 15, 2023 (edited) 6 hours ago, Capiert said: What does it mean to set the Kinetic_Energy's (KEd=m*(vf2-vi2)/2) initial_speed vi=0 to zero? KEd=m*(vf2-0)/2. (?) It means you're analyzing the problem in the object's initial reference frame. It may simplify the math a bit. 6 hours ago, Capiert said: what is the final_Kinetic_Energy KEf?; It's the object's kinetic energy at the end of the experiment. 6 hours ago, Capiert said: & what is the initial_Kinetic_Energy KEi?; It's the object's kinetic energy at the beginning of the experiment. It may be zero, but it doesn't have to be. 6 hours ago, Capiert said: what is the Kinetic_Energy(_difference) KEd? It's the difference between the final and the initial. Edited January 15, 2023 by Lorentz Jr
Capiert Posted January 20, 2023 Author Posted January 20, 2023 (edited) On 1/15/2023 at 9:41 PM, swansont said: What other “kinds” of KE are there? KEf=KEi+KEd That looks like 2 others to me. Yours is KEd=KEf-KEi, you let KEi=0. On 1/15/2023 at 9:41 PM, swansont said: I only know of the “kind” that is given by 1/2 mv^2 It can be applied to different particles and be measured/calculated at different times (hence you have initial and final as two common times) That's a good (interesting, simple) perspective. But what about KE transfer between (accelerating) masses that have acquired KE in similar times? Or is that what you mean (already)? I will assume the syntax could get a bit hairy. On 1/15/2023 at 9:41 PM, swansont said: Reference frames are incredibly useful for those that actually solve physics problems. On 1/15/2023 at 9:41 PM, swansont said: No. the difference in kinetic energy represents the change in kinetic energy at two different points in time. It is not a definition of KE. In other words you are saying, KE applies to only 1 accelerated mass. On 1/16/2023 at 12:17 AM, Lorentz Jr said: It means you're analyzing the problem in the object's initial reference frame. It may simplify the math a bit. It's the object's kinetic energy at the end of the experiment. It's the object's kinetic energy at the beginning of the experiment. It may be zero, but it doesn't have to be. How do we know (if) the initial_kinetic_energy KEi is zero or NOT? It (=KE) is always wrt the initial_speed of the reference_frame; but does that say or mean zero KE? If the reference frame is moving (which it surely is) then we can NOT say a static mass wrt to that reference_frame has absolutely NO KE. On 1/16/2023 at 12:17 AM, Lorentz Jr said: It's the difference between the final and the initial. Edited January 20, 2023 by Capiert
swansont Posted January 20, 2023 Posted January 20, 2023 23 minutes ago, Capiert said: KEf=KEi+KEd That looks like 2 others to me. Yours is KEd=KEf-KEi, you let KEi=0. Those are not “kinds” of KE. KEi and KEf are the kinetic energy at two points in time. 23 minutes ago, Capiert said: That's a good (interesting, simple) perspective. But what about KE transfer between (accelerating) masses that have acquired KE in similar times? What about it? There are several equations one might use to determine the KE, depending on the details of the problem. But there will still be a KE at the beginning if the problem, and one at the end. 23 minutes ago, Capiert said: In other words you are saying, KE applies to only 1 accelerated mass. No, I didn’t mean that, nor did I say that. Every object can have a value for KE. 23 minutes ago, Capiert said: How do we know (if) the initial_kinetic_energy KEi is zero or NOT? If the object is at rest, it has zero KE. v=0, and KE = 1/2 mv^2 1
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