Quote from: chazemz on 09/27/2017 04:19 pmYou are evading the question. The magnets will accelerate at ninety degrees to the direction of travel. As they accelerate, since they have mass, their momentum and kinetic energy will increase. Where is this energy coming from?You had to do "work" to bring the two magnets together. That stores potential energy. When you release them, that energy that YOU put in is released as they separate and converted into their motion.
You are evading the question. The magnets will accelerate at ninety degrees to the direction of travel. As they accelerate, since they have mass, their momentum and kinetic energy will increase. Where is this energy coming from?
Quote from: chazemz on 09/27/2017 04:19 pmYou are evading the question. The magnets will accelerate at ninety degrees to the direction of travel. As they accelerate, since they have mass, their momentum and kinetic energy will increase. Where is this energy coming from?I didn't avoid anything. I already answered this exact question twice.For the third time: Potential energy.https://en.wikipedia.org/wiki/Potential_energyAnd to be technical (which you should be when talking about physics) It is only their kinetic energy that increases. Total energy includes the potential energy, and therefore stays constant. And again, total momentum does not change.
I am really pleased that you have introduced potential energy, we will discuss this at a later date.So to be technical, both of you are saying that after the two magnets have joined, the velocity of the two magnets is the same as when they were released?
No, that was not my next question. I am however getting excited here. What you are saying is that the magnets can travel the extra distance without the need for any extra energy. Just to be cautious would this not contravene conservation of energy?
I feel we have covered enough ground to attempt a little game of chess with nature.
There was an objection raised that the device was using the initial counter rotation to enable the end result
Quote from: chazemz on 10/12/2017 04:44 pmI feel we have covered enough ground to attempt a little game of chess with nature.This is a terrible analogy. Nature is not the opponent in a game, if anything it is the rules of the game.Quote from: chazemz on 10/12/2017 04:44 pmThere was an objection raised that the device was using the initial counter rotation to enable the end resultYou apparently did not understand a thing that was said to you. The objection is that anyone who can do force balances (or torque balances in this case) would see that the angular momentum gained by the device at the end of the video was transferred to the device from the Earth through the string.You also only talked about conservation of energy in this post. Energy that allows the device to acquire kinetic energy clearly comes from the power supplied to the motor. The issue you are not recognizing is the completely separate question of momentum conservation (specifically angular momentum).The rest of your description fall back to your previous issues with communication, where you refer to adding a counter rotating device without explaining what part of the device it is attached to and whether it is counter rotating relative to the body (wooden part) or the arms.
Can you have kinetic energy without momentum?
angular momentum gained by the device at the end of the video was transferred to the device from the Earth through the stringHow?
Quote from: chazemz on 10/12/2017 06:54 pmangular momentum gained by the device at the end of the video was transferred to the device from the Earth through the stringHow?The string applies a torque. This was explained to you repeatedly in the other thread. You can easily see the torque by taking your device (while it is off), and rotating it 180 degrees. You will see the string then cause it to rotate back to the rest position (and then oscillate back and forth until dissipative forces such as air resistance bring it to rest).
Quote from: meberbs on 10/12/2017 07:04 pmQuote from: chazemz on 10/12/2017 06:54 pmangular momentum gained by the device at the end of the video was transferred to the device from the Earth through the stringHow?The string applies a torque. This was explained to you repeatedly in the other thread. You can easily see the torque by taking your device (while it is off), and rotating it 180 degrees. You will see the string then cause it to rotate back to the rest position (and then oscillate back and forth until dissipative forces such as air resistance bring it to rest).And I repeatedly told you that the string is not wound when the power is switched off. So the string applies no torque to the device at that moment.
Quote from: chazemz on 10/12/2017 07:25 pmQuote from: meberbs on 10/12/2017 07:04 pmQuote from: chazemz on 10/12/2017 06:54 pmangular momentum gained by the device at the end of the video was transferred to the device from the Earth through the stringHow?The string applies a torque. This was explained to you repeatedly in the other thread. You can easily see the torque by taking your device (while it is off), and rotating it 180 degrees. You will see the string then cause it to rotate back to the rest position (and then oscillate back and forth until dissipative forces such as air resistance bring it to rest).And I repeatedly told you that the string is not wound when the power is switched off. So the string applies no torque to the device at that moment.And you have been repeatedly told the state of the string when the device is turned off is irrelevant. While the device is on, the string applies torques. The net result of all of these torques while the device is on is the angular momentum the device has at the moment that you turn it off.
Quote from: meberbs on 10/12/2017 07:58 pmAnd you have been repeatedly told the state of the string when the device is turned off is irrelevant. While the device is on, the string applies torques. The net result of all of these torques while the device is on is the angular momentum the device has at the moment that you turn it off.The state of the string when the device is switched off is everything. It is the only thing that can apply an exterior force(torque) to the device at that moment. Since the string applies zero torque at that time, it has no influence on the observed result.
And you have been repeatedly told the state of the string when the device is turned off is irrelevant. While the device is on, the string applies torques. The net result of all of these torques while the device is on is the angular momentum the device has at the moment that you turn it off.
Quote from: chazemz on 10/13/2017 02:56 pmQuote from: meberbs on 10/12/2017 07:58 pmAnd you have been repeatedly told the state of the string when the device is turned off is irrelevant. While the device is on, the string applies torques. The net result of all of these torques while the device is on is the angular momentum the device has at the moment that you turn it off.The state of the string when the device is switched off is everything. It is the only thing that can apply an exterior force(torque) to the device at that moment. Since the string applies zero torque at that time, it has no influence on the observed result.Which words in my previous post did you not understand? Your response sounds like you did not read anything other than the first sentence of my post, because you did not address the simple fact that the string had already transferred angular momentum to the device. You can clearly see in the video that the device has angular momentum just before you turn it off. Therefore, it doesn't need any more torques applied to it for it to continue to spin.
The acceleration of the rotor arms has nothing to do with the string.
Since there is no counter rotation of the body when the rotor arms accelerate just before switch off,
being wrong is good, it means I am learning. We could go round and round (no pun intended) with the string so I am going to move on with my next post.