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Sum of energy not at 0 in that movement
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Sum of energy not at 0 in that movement
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LB7
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Ludovic Bavay Ubeda
Re: Sum of energy not at 0 in that movement
«
Reply #40 on:
29/05/2020 15:52:13 »
To have the force in the other direction on the circle and on the red wall, I can rotate the circle around its center in the same time. In that case the force from friction helps to move to the right the circle. At the limit, I have no energy from friction but I have the forces, I lost d2F from the rotation of the circle and I win d1F from the translation of the circle.
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Ludovic Bavay 19011971 Valenciennes
LB7
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Ludovic Bavay Ubeda
Re: Sum of energy not at 0 in that movement
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Reply #41 on:
08/06/2020 15:04:06 »
The method is more:
1/ draw the objects at the initial and final positions
2/ group the objects at the final position and rotate back to have the same orientation of the initial position
3/
3.1/ place A0 the common dot, measure the distance moved by the dot of contact
3.2/ place the center of the circle the common dot, measure the distance moved by the dot of contact
4/ calculate the algebric sum: this is the distance of friction
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Ludovic Bavay 19011971 Valenciennes
LB7
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Ludovic Bavay Ubeda
Re: Sum of energy not at 0 in that movement
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Reply #42 on:
09/06/2020 10:39:23 »
I think the principle: the work doesn't depend of the path is false because if I decomposed the movement in 3 movement:
1/ the red arm is fixed, I move the circle along the red arm
2/ I glue the circle and the red wall, I rotate that group
3/ the red arm is fixed, I rotate the circle
in that case, the sum of energy is conserved. So the combination of 2 movement in the same time changes the result.
When I write the method:
1/ draw the start and final position
2/ group the all objects in the final position
3/ rotate the group of the final position back to have the same orientation for one object (the wall for example)
4/ rotate one object forward (the circle for example) of : the relative rotation of one object to the other less the difference of the orientation of the dot of contact
5/ measure the distance of friction.
I need to precise, "the difference of the orientation of the dot of contact" is measured after the dot 3/, it is not the true orientation, it is the orientation after rotate back the group.
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Last Edit: 09/06/2020 19:50:40 by
LB7
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