Momentum is a vector i.e. has magnitude & direction - Energy is scalar i.e. has magnitude but NOT direction - they are not interchangeable - force is a vector.
e.g. two sets of objects closing on a collision course head-on, one set both at 10 m/s & an identical arrangement closing at 100 m/s each - net momentum is zero for both sets yet the energy of motion [Ke] is quite different - this energy is a result of mass & velocity but bears no relation to the net momentum accounting sums - after collision the objects have different momentum vectors [still netting to zero] & new velocities, ergo, new Ke.
so, when relative velocities are greatest we have greater Pe & Ke after impact - you cannot IMO only account for one side of the ledger with momentum i.e. you must use double entry bookkeeping [sum the system] then the variable will be the Ke available to do work, & this is proportional to their relative velocities.
Impact is not the Key
Moderator: scott
re: Impact is not the Key
In your head on collision (100 m/sec) with the momentum allegedly being zero, what if you catch one object on the end of a string just before it collides with the other object. What if you directed the object 180° around the circle and released it moving in the same direction as the other object (let both be 1 kg). You have changed your alleged zero into 200 units of momentum. There seems to be something wrong with your concept of mechanics.
It was always 200 units. F = ma: Where do you put in direction, I don’t see any direction in the formula.
The two objects acquired their momentum independently of each other, they don’t care what direction the other guy is moving in. It is like saying a train in Kansas has no momentum because there is one in Montana traveling in the opposite direction (there are two states between). Didn’t it take fuel (force) to get both trains up to speed? This vector sum nonsense is crazy. You must have opposing interaction; until they begin to interact their momentums are independent of the other.
And the top of a moving wheel is not opposing the bottom of the wheel.
Atwood’s machines are used to prove F = ma and the suspended masses are moving in opposite directions. How can you prove F = ma if momentum remains zero, this vector sum nonsense is crazy.
You are improperly using vector sums.
It was always 200 units. F = ma: Where do you put in direction, I don’t see any direction in the formula.
The two objects acquired their momentum independently of each other, they don’t care what direction the other guy is moving in. It is like saying a train in Kansas has no momentum because there is one in Montana traveling in the opposite direction (there are two states between). Didn’t it take fuel (force) to get both trains up to speed? This vector sum nonsense is crazy. You must have opposing interaction; until they begin to interact their momentums are independent of the other.
And the top of a moving wheel is not opposing the bottom of the wheel.
Atwood’s machines are used to prove F = ma and the suspended masses are moving in opposite directions. How can you prove F = ma if momentum remains zero, this vector sum nonsense is crazy.
You are improperly using vector sums.
re: Impact is not the Key
And you give your own proof pequaide - two trains moving at equal speed in opposite directions have individual momentum vectors that if summed into one system would be zero - but at this stage they are not physically linked or interacting so you treat them as singular & unrelated - we know how much energy it takes to accelerate them up to a speed & it's the same energy required to stop them [assuming they started from a dead stop], & this is given by the kinetic energy formula.
This is where I believe the momentumists come unstuck - the very act of trying to capture or use Ke [energy of velocity or motion] requires an intervention or interaction with another physical body [kinematics] - it is the same for trying to harness Cf's - you can develop a force but the moment you try to apply it to shift or influence something else, the other body's momentum vector comes into the equation - this applies whether you are colliding head on or tethering it on a string that it swings around - the string itself must also be anchored to a body & its momentum changed in turn.
If we want to change the velocity of something with mass it must be acted on by a force & that will result in new velocities [Ke's] but as soon as the parts interact the individual momentums come into the one system & that's why momentums [locally] zero out - nothing can be treated as isolated unless a convenient subset is only looked at & that's not proper book-keeping, IMO.
This is where I believe the momentumists come unstuck - the very act of trying to capture or use Ke [energy of velocity or motion] requires an intervention or interaction with another physical body [kinematics] - it is the same for trying to harness Cf's - you can develop a force but the moment you try to apply it to shift or influence something else, the other body's momentum vector comes into the equation - this applies whether you are colliding head on or tethering it on a string that it swings around - the string itself must also be anchored to a body & its momentum changed in turn.
If we want to change the velocity of something with mass it must be acted on by a force & that will result in new velocities [Ke's] but as soon as the parts interact the individual momentums come into the one system & that's why momentums [locally] zero out - nothing can be treated as isolated unless a convenient subset is only looked at & that's not proper book-keeping, IMO.
re: Impact is not the Key
The difference between me and you is that I do experiments. I don’t just keep the books.
If your 1 kg moving 100 m/sec right is at the top of a wheel and the 1 kg moving left 100 m/sec is at the bottom of a wheel the momentum of the system is not zero. You can wrap a string around the wheel and make it pull an object across a frictionless plane and the momentum shared with the object will be a clear F = ma relationship. Linear Newtonian momentum will be conserved. This is not book keeping it is experimental fact.
You could also isolate all the motion of the wheel into a small portion of its own mass that is then moving in a linear path. By experimental fact; the small object has all the linear Newtonian momentum that previously existed in the wheel, and the energy is much higher.
I have nothing against books; I have a half dozen texts in my personal possession, but there are great discrepancies in those books, sometimes to the point of being laughable. Sometime the best way to support the books is to lay them down and do some experiments.
If your 1 kg moving 100 m/sec right is at the top of a wheel and the 1 kg moving left 100 m/sec is at the bottom of a wheel the momentum of the system is not zero. You can wrap a string around the wheel and make it pull an object across a frictionless plane and the momentum shared with the object will be a clear F = ma relationship. Linear Newtonian momentum will be conserved. This is not book keeping it is experimental fact.
You could also isolate all the motion of the wheel into a small portion of its own mass that is then moving in a linear path. By experimental fact; the small object has all the linear Newtonian momentum that previously existed in the wheel, and the energy is much higher.
I have nothing against books; I have a half dozen texts in my personal possession, but there are great discrepancies in those books, sometimes to the point of being laughable. Sometime the best way to support the books is to lay them down and do some experiments.
re: Impact is not the Key
Maybe the real difference pequaide is that Fletcher shows some grace. If you knew Fletcher you'd know he does experiments.The difference between me and you is that I do experiments. I don’t just keep the books.
meChANical Man.
--------------------
"All things move according to the whims of the great magnet"; Hunter S. Thompson.
--------------------
"All things move according to the whims of the great magnet"; Hunter S. Thompson.
re: Impact is not the Key
You mean the velocity is much higher?pequaide wrote:You could also isolate all the motion of the wheel into a small portion of its own mass that is then moving in a linear path. By experimental fact; the small object has all the linear Newtonian momentum that previously existed in the wheel, and the energy is much higher.
re: Impact is not the Key
You have a misconception about me pequiade - I've spent over a decade doing mechanical experiments in an effort to find & exploit a loop hole in conventional physics, so far, no cigar.
The acid test always being to get an object or system to a higher potential than when it started, by whatever means, short of combustion or fraud.
Your challenge, as is mine, is to create the experiment that can prove this gain in energy of potential when all known things are accounted for - this would side-step the necessity to explain things in accepted physics terms & descriptions [which we might argue about the semantics] & wow the audience by power of undeniable demonstration alone - of course, the die-hards amongst us [like me I suppose] would want to try & explain the raising of potential into the system with no other compensatory losses with the tools we have been brought up with or learned ourselves from the people before us who contributed to the textbooks.
Can you demonstrate a gain in system potential [with your experiments] that can be used to do work & then returns the system to its original starting potential, to repeat the cycle ?
The acid test always being to get an object or system to a higher potential than when it started, by whatever means, short of combustion or fraud.
Your challenge, as is mine, is to create the experiment that can prove this gain in energy of potential when all known things are accounted for - this would side-step the necessity to explain things in accepted physics terms & descriptions [which we might argue about the semantics] & wow the audience by power of undeniable demonstration alone - of course, the die-hards amongst us [like me I suppose] would want to try & explain the raising of potential into the system with no other compensatory losses with the tools we have been brought up with or learned ourselves from the people before us who contributed to the textbooks.
Can you demonstrate a gain in system potential [with your experiments] that can be used to do work & then returns the system to its original starting potential, to repeat the cycle ?
re: Impact is not the Key
Jerry, those are some powerful NIB's. The banana impact is my favorite. Notice how much work the guy has to do in order to pry apart those big magnets. Interestingly, that looks about the same amount of work required to squash a banana. Coincidence? :)
re: Impact is not the Key
Hi Fletcher.
Speaking of digestion systems.
take a bowl of Nitric Acid and place the bowl in another Bowl of liquid Nitrogen, freeze the Nitric Acid, then remove said acid and place on table, place one drop of water on said acid, what happens?
please wear safety goggles when doing this experiment.
Jerry
Speaking of digestion systems.
take a bowl of Nitric Acid and place the bowl in another Bowl of liquid Nitrogen, freeze the Nitric Acid, then remove said acid and place on table, place one drop of water on said acid, what happens?
please wear safety goggles when doing this experiment.
Jerry
re: Impact is not the Key
Don't have any bowls of those lying around ;) - hmm, at a guess I'd say something explodes i.e. rapid release of energy by conversion of solid to vapour [sublimation etc] - but then the liquid nitrogen had to be mechanically cooled & that took energy at the very start [when looking at the totality of the system] & it did warm a little in comparison to the nitric acid freezing, so entropy was a condition & was not violated ???
re: Impact is not the Key
On a frictionless plane I take a four mass disk and pucks system and give all the motion to the one mass pucks. And yes the velocity is higher, a little under four times higher.
That is when you hit the books. 1/2mv², ½ * 4 * 1 * 1 = 2 joules for initial energy, ½ * 1 * 4 * 4 = 8 joules for final energy.
Or you could use the distance formula for the same results d =1/2v²/a, or d =1/2at². The four units of mass can rise .05096 m and the 1 unit of mass can rise .8155 m. You could have dropped the four units .05096 meters and ended with one unit of mass at .8155 m.
Success would be more likely, when approaching corporations, if more people had made a few of these experiments. The experiments are cheaper and take less effort to make than the one used to mash his lunch.
That is when you hit the books. 1/2mv², ½ * 4 * 1 * 1 = 2 joules for initial energy, ½ * 1 * 4 * 4 = 8 joules for final energy.
Or you could use the distance formula for the same results d =1/2v²/a, or d =1/2at². The four units of mass can rise .05096 m and the 1 unit of mass can rise .8155 m. You could have dropped the four units .05096 meters and ended with one unit of mass at .8155 m.
Success would be more likely, when approaching corporations, if more people had made a few of these experiments. The experiments are cheaper and take less effort to make than the one used to mash his lunch.
re: Impact is not the Key
You might also try thinking of it in terms of a nut and bolt with equal mass approaching each other to mesh, both tavelling at the same speed and with the same rate of spin in opposite directions to each another.
In short they are both forcing and being forced on their way equally by one another, but those forces and the paths they must travel as a result are entirely "complimentary" and without any resistance to the ones they're on and wind up making them both go just that much faster because of it.
What I had in mind was perfect combining of energies in such a way that they are at least doubled and remain that way for both, however odd or contradictory to any particular "laws" that might sound.
It is a most unusual case, and one that bears some thinking on.
If the nut is stationary and for arguement's sake we say that the thread of it is such that that our travelling bolt's own rotation ahould take it clean through with no loss of speed, then spinning the nut at the same rate in the opposite direction while it's still stationary ought wind or propel the bolt through it twice as fast, should it not? lol
And of course, if we add speed into that equation by having our nut approach the bolt at the very same speed it's coming at it, well...
what then?
In short they are both forcing and being forced on their way equally by one another, but those forces and the paths they must travel as a result are entirely "complimentary" and without any resistance to the ones they're on and wind up making them both go just that much faster because of it.
What I had in mind was perfect combining of energies in such a way that they are at least doubled and remain that way for both, however odd or contradictory to any particular "laws" that might sound.
It is a most unusual case, and one that bears some thinking on.
If the nut is stationary and for arguement's sake we say that the thread of it is such that that our travelling bolt's own rotation ahould take it clean through with no loss of speed, then spinning the nut at the same rate in the opposite direction while it's still stationary ought wind or propel the bolt through it twice as fast, should it not? lol
And of course, if we add speed into that equation by having our nut approach the bolt at the very same speed it's coming at it, well...
what then?
re: Impact is not the Key
If impact is the "key", then why doesn't my simple sim show a "harvest" of energy from the acceleration of the falling/ impacting weight??
ANSWER: When a mass falls on one side of a pivot, a mass also falls on the opposite side of the pivot.
I don't know why you all can't get that into your heads.
Bessler's wheel worked, but not by impacting weights.
Axel
ANSWER: When a mass falls on one side of a pivot, a mass also falls on the opposite side of the pivot.
I don't know why you all can't get that into your heads.
Bessler's wheel worked, but not by impacting weights.
Axel
Suppose that a mechanism were to use leverage to transfer most of the inertial momentum of one weight to another weight such that the first weight almost stops moving and the second weight almost doubles in speed, and that it does this naturally without using any extra energy.
The second weight moving at almost twice the speed of the wheel impacts the wheel pushing it forward. This brings the speed of the second weight back to the original speed of the first, and because the two weights are leveraged together, it brings the first weight back to the speed of the second weight. Thus the two weights have exchanged places, and the cycle repeats. Extra energy is available because when a weight doubles in speed its KE its quadruples.
Thus impact could be part of the solution but not the total solution. So do not say, "Bessler's wheel worked, but not by impacting weights."
The second weight moving at almost twice the speed of the wheel impacts the wheel pushing it forward. This brings the speed of the second weight back to the original speed of the first, and because the two weights are leveraged together, it brings the first weight back to the speed of the second weight. Thus the two weights have exchanged places, and the cycle repeats. Extra energy is available because when a weight doubles in speed its KE its quadruples.
Thus impact could be part of the solution but not the total solution. So do not say, "Bessler's wheel worked, but not by impacting weights."