What if inertial mass did NOT = grav. mass?

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Discussion Overview

The discussion explores the hypothetical scenario in which inertial mass does not equal gravitational mass, examining how this difference might affect everyday experiences and physical interactions. Participants engage in creative reasoning about the implications for various activities, such as walking, throwing objects, and the behavior of celestial bodies.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that if inertial mass and gravitational mass were not equal, it could lead to heavier objects falling faster than lighter ones, challenging the equivalence principle.
  • Others propose that if gravitational mass were greater than inertial mass, it would validate Aristotle's view that heavier objects fall faster.
  • A different perspective posits that if inertial mass were greater, lighter objects might fall faster than heavier ones, leading to unusual physical experiences.
  • One participant questions how the resistance to motion could differ between forces, arguing that force is force regardless of the type.
  • Several participants engage in thought experiments regarding the gravitational interaction between two Earth-sized planets, discussing whether they would accelerate towards each other at 9.8 m/s².
  • Some participants reflect on the implications of carrying objects of different weights, considering how their differing inertial and gravitational responses might feel in practice.
  • There is a mention of Eotvos' experiments, which have demonstrated the equivalence of the two masses to a high degree of precision, although some participants emphasize that the discussion is hypothetical.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the implications of differing inertial and gravitational mass, with multiple competing views and speculative scenarios presented throughout the discussion.

Contextual Notes

The discussion includes various assumptions and hypothetical scenarios, with some participants acknowledging the established equivalence of inertial and gravitational mass while exploring the consequences of a hypothetical divergence.

  • #91
Noted Jorrie. It's an interesting one this. That 2a means the falling is faster, but dropping two objects also says it isn't. Hmmn.

I wonder if the Earth would have a different orbit if the moon wasn't there?
 
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  • #92
Farsight said:
Noted Jorrie. It's an interesting one this. That 2a means the falling is faster, but dropping two objects also says it isn't. Hmmn.

I wonder if the Earth would have a different orbit if the moon wasn't there?

I think there would have been a minor difference - instead of the Earth cycling around the Earth-Moon baricentre every 28 days or so, the Earth would have had a more standard elliptical orbit around the Sun.

IMO, the crucial point is that the mass of the orbiting object has negligible effect on the orbit, as long as its mass is small compared to the primary mass (the Sun in this case). So the Earth-Moon baricentre follows an orbit that is roughly independent of the mass of the Earth-Moon system.
 
  • #93
Thanks Jorrie.
 

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