Simple pendulum in different situations

In summary, the conversation discusses the potential differences in the time periods of a pendulum depending on whether it is filled with water or if the water inside freezes. There is some disagreement among the participants, but it is generally agreed upon that under certain conditions, such as no friction and neglecting changes in volume, the period of the pendulum will remain the same regardless of what is inside, making it mass independent. Some suggest that this may not be a realistic scenario, as in the real world, the pendulum would not be completely massless or frictionless.
  • #1
Adikshith Ojha
3
1
Say there is a pendulum which is suspended by a massless thread or rod or whatever, the bob is spherical and hollow. Now consider 2 cases 1) the pendulum is completely filled with water 2) the water inside freezes. will there be a difference in the time periods? If so, why?
 
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  • #2
My first instinct is that not only will the period be different, but the behavior may even become chaotic when the water is liquid, like a double-pendulum.
The water sloshing inside the bob would add an extra degree of freedom, like a second pendulum.

Unless the bob is completely filled with water. I wouldn't expect a difference in that case.
 
  • #3
If you disregard the friction of the water, isn't the water stationary? Also, if the water freezes, the bob has to expand right? since the period of a pendulum is 2pisqrt(l/g), there would be no difference. However, if the bob expands, that would slightly change l.
 
  • #4
Well, I guess I should've stated some more conditions (being a student, I take them for granted) there is no friction due to water and neglect any changes in volume. Anyway, both of you say that there is Jo change, that must be it then.
 
  • #5
Equation needed: T=2π√(L/G). If the water is uniformly distributed and also fills up the entire sphere (to avoid sloshing which changes this whole problem), and we're ignorning friction, expansion, etc... Then no there should be no difference. The bob's center of mass remains in the center of the water (liquid/ice) as you can treat a sphere filled completely with water as a "solid" mass (ignoring the complicated stuff as this appears to).
 
  • #6
Exactly what the previous poster mentioned. Because of your given constraints, and not a real world scenario, the Pendulum is mass independent. Therefore, I could fill it up with hot sauce, and the answer would be the same.
 
  • #7
MidgetDwarf said:
Exactly what the previous poster mentioned. Because of your given constraints, and not a real world scenario, the Pendulum is mass independent. Therefore, I could fill it up with hot sauce, and the answer would be the same.
I think you need to clarify this. Pendulum is not mass independent.
 
  • #8
just dani ok said:
I think you need to clarify this. Pendulum is not mass independent.
the period of the pendulum is mass independent.
 
  • #9
MidgetDwarf said:
the period of the pendulum is mass independent.
sorry, my mistake.
 

Related to Simple pendulum in different situations

1. How does the length of a pendulum affect its period?

The period of a pendulum is directly proportional to the square root of its length. This means that as the length of the pendulum increases, its period also increases.

2. Does the mass of a pendulum affect its motion?

The mass of a pendulum does not affect its motion, as long as the mass is concentrated at the end of the pendulum (the bob). This is because the motion of a pendulum is determined by its length and the force of gravity, not its mass.

3. How does the angle of release affect a pendulum's swing?

The angle of release, or the angle at which the pendulum is pulled back before being released, affects the amplitude of the pendulum's swing. A larger angle will result in a larger amplitude, while a smaller angle will result in a smaller amplitude.

4. Can a pendulum swing indefinitely?

In theory, a pendulum can swing indefinitely if there is no friction or air resistance present to slow it down. However, in real-world situations, a pendulum will eventually slow down and come to a stop due to factors such as air resistance and friction.

5. How does gravity affect a pendulum's motion on different planets?

The force of gravity on a planet affects the period of a pendulum, as well as the length and amplitude of its swing. On a planet with a stronger gravitational force, the pendulum will have a shorter period and a smaller amplitude. On a planet with a weaker gravitational force, the pendulum will have a longer period and a larger amplitude.

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