Testing the effect of Gravity at home....

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Discussion Overview

The discussion revolves around the effects of gravity and air resistance on the falling rates of objects of different masses, specifically comparing a ping pong ball and a lead ball of the same dimensions when dropped from shoulder height. Participants explore the implications of air resistance, terminal velocity, and the conditions necessary for a fair comparison in a home experiment.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants assert that in a vacuum, all objects fall at the same rate regardless of mass, while in air, different masses experience different effects due to air resistance.
  • One participant suggests that a ping pong ball will lag behind a lead ball when dropped from shoulder height unless air resistance is eliminated.
  • Another participant questions why air resistance would differ if both balls have the same shape, volume, and surface area, leading to a discussion about the relationship between mass and acceleration.
  • Some participants propose that while both balls will fall at different rates initially, they may hit the ground at approximately the same time in a practical setting due to the small height involved.
  • There is mention of the complexities introduced by different mediums (like air) affecting the falling objects, which complicates the understanding of gravity's action.
  • Participants reference Galileo's experiments to draw parallels with the current discussion, questioning whether the principles observed in those experiments apply to the home experiment scenario.
  • Some suggest using mathematical models to clarify the behavior of the balls under different conditions, including the effects of drag.

Areas of Agreement / Disagreement

Participants express differing views on the effects of air resistance and the conditions under which the two balls would fall at the same rate. There is no consensus on the implications of these factors, and the discussion remains unresolved regarding the practical outcomes of the proposed home experiment.

Contextual Notes

Participants acknowledge that the accuracy of the experiment may be affected by the difficulty of releasing the balls simultaneously and from the same height, as well as the assumptions made about air resistance and terminal velocity.

  • #31
Music in a group requires coordinating movements between different people with probably microseconds precision. Watch videos of a drumline to see such precision visually.

The real problems with dropping two objects, especially of different weights, are that it isn't a decisive movement, isn't the same movement for each hand and small variations in hand position and friction can significantly affect the outcome. This can be fixed by using a decisive release mechanism instead of dropping manually.
 
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  • #32
jbriggs444 said:
do not think that "reaction time" is the correct figure of merit here.
I've just been dropping a pair of marbles on to blutack, so they thump but don't bounce. I dropped one from 10cm and the other from 15, 20, and 30cm. I reckon that there was a single sound for the 10cm vs 15cm drop, a just about noticeable d-dump sound with the 20cm vs 10cm trial, and a clear double sound with the 30cm vs 10cm trial. I wasn't blinded or anything, so treat with caution, but that suggests that a 30ms difference isn't detectable, 60ms is just about, and 100ms is clear.

Considering that the guy in the video is dropping from waist height (~1m) I get a drop time of 450ms, suggesting that around 10-15% difference in drop times would be audible.

There's a lot to criticize about that experiment. I was just letting go of the marbles not using a mechanism, I didn't clean them after their impacts on the blutack, and I wasn't blinded to the release heights. But there are some rough numbers. Could probably do something more sophisticated if someone has a suggestion for an adjustable height simultaneous release mechanism...
 
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  • #33
An on-point experiment gets high marks in my book. Nicely low tech too.
 
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  • #34
gmax137 said:
1869?
That's the kind of little mistake that makes me question the whole thing...
And a bit of dyslexia might be excused but it was 1687 according to my researches...
 
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