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Glenn G
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Assume a pendulum was swinging in a lift. If the cable breaks and the lift starts to accelerate down at g would the pendulum stop swinging and freeze in its current position?
Merry Xmas.
G.
Merry Xmas.
G.
Glenn G said:Assume a pendulum was swinging in a lift. If the cable breaks and the lift starts to accelerate down at g would the pendulum stop swinging and freeze in its current position?
Merry Xmas.
G.
The bob was originally following a circular path. It would (in general) have a vertical and horizontal component to its velocity. and tension in the string So it would continue to move sideways and vertically relative to the lift cage if the pivot point started to accelerate downwards at g. There would / could still be some tension in the string (details depending on the part of the cycle of the pendulum. The only situation in which the bob would carry on down in the same position relative to the lift cage would be if the cable broke when the pendulum was horizontal, at which point there would be no tension and the acceleration of the bob would just be g. Only then it would appear "frozen".lekh2003 said:Yes it would, assuming the lift is accelerating exactly at g. The only thing keeping the pendulum moving was the acceleration downward relative to its surroundings. If its surroundings are accelerating downwards, then the pendulum should stay still.
Ahh, thanks for the correction.sophiecentaur said:So it would continue to move sideways and vertically relative to the lift cage if the pivot point started to accelerate downwards at g.
That isn't correct though. The pendulum could have zero kinetic energy when it is at any angle. It doesn't have to be completely horizontal. It will not move when it has zero kinetic energy.sophiecentaur said:The only situation in which the bob would carry on down in the same position relative to the lift cage would be if the cable broke when the pendulum was horizontal, at which point there would be no tension and the acceleration of the bob would just be g.
Oh yes, I think you're right there. Any situation where the bob is stationary wrt the lift frame (extremity of its swing), the tension would disappear etc. etc.lekh2003 said:That isn't correct though. The pendulum could have zero kinetic energy when it is at any angle. It doesn't have to be completely horizontal.
A pendulum is a weight suspended from a fixed point that swings back and forth due to the force of gravity. The swinging motion is caused by the pendulum's potential energy being converted into kinetic energy as it moves.
No, a pendulum will not continue to swing in a falling lift. This is because the lift and everything inside it, including the pendulum, are in a state of free fall. This means that there is no external force acting on the pendulum to keep it swinging.
A pendulum stops swinging in a falling lift because it is in a state of free fall. Gravity is the only force acting on the pendulum, and as the lift falls, the pendulum and the lift are falling at the same rate. This means that there is no relative motion between the pendulum and the lift, causing the pendulum to appear as if it is at rest.
No, even if the pendulum is attached to the lift, it will not continue to swing in a falling lift. This is because both the lift and the pendulum are in a state of free fall and there is no relative motion between them. The attachment will not change this fact.
Yes, the pendulum is affected by the acceleration of the lift in free fall. However, since both the lift and the pendulum are in a state of free fall, the acceleration does not cause any relative motion between them. Therefore, the pendulum appears to be at rest as the lift falls.