Does weight affect an object's speed during free fall?

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Discussion Overview

The discussion revolves around the relationship between weight and the speed of objects in free fall, specifically addressing whether weight affects the speed of falling objects when air resistance is not considered. The context includes theoretical considerations and clarifications of fundamental physics principles.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asserts that all objects fall at the same speed in a vacuum, using the example of a feather and a bowling ball on the moon.
  • Another participant agrees that the force of gravity on the bowling ball is greater due to its larger mass but emphasizes that the acceleration remains the same for both objects, referencing Newton's second law.
  • A third participant reiterates that while weight and mass differ, the acceleration due to gravity is constant, thus leading to the same falling speed in a vacuum.
  • There is a mention of terminal speed, where air resistance plays a role, indicating that in a vacuum, objects fall at the same speed regardless of weight.
  • A participant references an FAQ for further information on the topic.

Areas of Agreement / Disagreement

Participants generally agree that in a vacuum, weight does not affect the speed of falling objects, as they fall at the same acceleration due to gravity. However, there is some confusion regarding the implications of weight and mass on speed, indicating a nuanced understanding of the concepts involved.

Contextual Notes

The discussion does not resolve the initial confusion expressed by the first participant regarding the relationship between weight and speed, highlighting the need for further clarification on these concepts.

musicboy
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Hi there
Just wondering: all objects fall at the same speed, right(not taking into account air resistance)? So if I dropped a feather and a bowling ball on the moon, they'd fall at the same speed. So far so good.
But my physics book's definition of weight is "The weight of an object is the force that acts on it because of gravity; Weight = Mass x Acceleration due to gravity" .
The bowling ball's mass is clearly greater than the feather's, so therefore it's weight and therefore pull of gravity on it must be different, resulting in a different speed...
Confused!
Any help much appreciated :)
 
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hi musicboy! :smile:
musicboy said:
… my physics book's definition of weight is "The weight of an object is the force that acts on it because of gravity; Weight = Mass x Acceleration due to gravity" .
The bowling ball's mass is clearly greater than the feather's, so therefore it's weight and therefore pull of gravity on it must be different, resulting in a different speed...

yes, the force of gravity on it is greater (Mg > mg)

but force = mass times acceleration (that's Newton's second law),

so the accelerations are the same (A = Mg/M, a = mg/m) :wink:
 
musicboy said:
Weight = Mass x Acceleration...

The bowling ball's mass is clearly greater than the feather's, so therefore it's weight and therefore pull of gravity on it must be different,
You have the equation right there. If you change Weight & Mass by the same factor, Acceleration stays the same.

musicboy said:
resulting in a different speed...
The terminal speed, where air resistance = weight, is different. But in vacuum they fall the same.
 
To add to what A.T. And Tiny-Tim have said... There's an FAQ on this at https://www.physicsforums.com/forumdisplay.php?f=209
 
Last edited by a moderator:
Gotcha :)
Thanks very much all of you for quick and concise replies.
Have a good day :D
 

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