Does the ideal Pendulum slow down?
Started by RetailBoy
p=mv
From /my/ understanding, when something stops, momentum cannot be considered conserved.
Like the pendulum and spring both stop at at max displacement/height and then change directions.
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Momentum of the SYSTEM is conserved unless some outside force acts upon the system (friction, air "resistance", etc) in absence of any outside force/torque, the ideal pendulum shouldnt slow down. Because there is conservation of energy, as you described, from PE to KE and back...
Doesnt whether it "slows down" depends on the distance from equilibrium(spring)? In a free swing pendulum, as the bob reaches the highest angle (max displacment) velocity slows to zero, thus the change from KE to PE. I'll break out real thinking in the morning.
At least that's my rationalization. But I'm so burned out I could be completely BSing.
Doesnt whether it "slows down" depends on the distance from equilibrium(spring)? In a free swing pendulum, as the bob reaches the highest angle (max displacment) velocity slows to zero, thus the change from KE to PE. I'll break out real thinking in the morning.
At least that's my rationalization. But I'm so burned out I could be completely BSing.
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Provided there is no friction in the hinge and no air resistance, it will not slow done nor stop. As you said, energy is conserved and there is nothing to stop the continuous exchange KE<->PE.
Momentum is also preserved - you need to look at the correct system. In that case the force on the pendulum is exerted by the Earth, via the gravity force - you'll have to include it in the system when calculating the total momentum. There is a tension force from the attachment point as well, so that needs to part of the system too. At the end, you cannot calculate anything practical this way but you can rest assured that no momentum was lost (or harmed) during that experiment. 😉
Momentum is also preserved - you need to look at the correct system. In that case the force on the pendulum is exerted by the Earth, via the gravity force - you'll have to include it in the system when calculating the total momentum. There is a tension force from the attachment point as well, so that needs to part of the system too. At the end, you cannot calculate anything practical this way but you can rest assured that no momentum was lost (or harmed) during that experiment. 😉
Well, if you mean slow down as in velocity decreases, yes. It slows down every oscillation. At Max height, v is zero.
But agree with everyone else in saying that in an ideal pendulum energy is conserved.
But agree with everyone else in saying that in an ideal pendulum energy is conserved.
Tricky, but good point.
