Question about acceleration and gravity

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    Acceleration Gravity
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Discussion Overview

The discussion revolves around the concept of g-force and the relationship between mass, weight, and acceleration, particularly in the context of an object on a platform accelerating in space and on Earth. Participants explore the implications of acceleration on perceived weight and the correct terminology for mass and force.

Discussion Character

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

Main Points Raised

  • One participant questions whether a 100 kg mass on an accelerating platform would have a weight of 1000 kg, seeking clarification on the concept of g-force.
  • Another participant clarifies that weight is a force measured in Newtons, not kilograms, and provides calculations for the force on the platform and the equivalent force experienced on Earth.
  • It is noted that the force required to accelerate a 100 kg mass at 10 m/s² in a weightless environment is 1000 N, emphasizing the distinction between mass and weight.
  • Participants discuss the implications of using weighing scales, which are typically calibrated for Earth's gravity, and how they would give incorrect readings on the Moon.
  • There is a question about whether a person on the platform would feel weightless if the platform were on Earth, with a later reply indicating that they would feel about 2g due to the upward acceleration.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of weight and the effects of acceleration, with some clarifying terminology while others question the implications of acceleration on perceived weight. The discussion remains unresolved regarding the specific experiences of individuals on the platform under different conditions.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the environment (e.g., weightlessness, air resistance) and the definitions of mass and weight, which are not universally agreed upon in the context provided.

raeshun
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I am having trouble understanding g-force.So if a object with a mass of 100 kg is sitting on a platform in space.If the platform was accelerating at 10 m/s^2 upwards would the weight of the object be 1000 kg? If so why?
 
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The force on the platform would be

F=ma
=100kg x 10m/s2
=1000 Newtons (not Kg)

On Earth the force on the ground would be

F=mg
=100kg x 9.8m/s2
=980 Newtons.

About the same. So if this 100kg mass on the platform was a man he would feel roughly the same as he does on Earth (eg 1g).

To be precise he would be experiencing 10/9.8 = 1.02g
 
raeshun said:
I am having trouble understanding g-force.So if a object with a mass of 100 kg is sitting on a platform in space.If the platform was accelerating at 10 m/s^2 upwards would the weight of the object be 1000 kg? If so why?
The kg is a measure of mass, not force. Weight is a force. So a "weight of 100kg" is scientifically incorrect. It is used in everyday speech to stand for "the force exerted by gravity at the Earth's surface on a 100kg mass", but in scientific terms that's (approximately) 1000 Newtons. Likewise, the force required to accelerate a 100kg mass at 10m/s2 in a weightless environment is 1000 N.
 
CWatters said:
The force on the platform would be

F=ma
=100kg x 10m/s2
=1000 Newtons (not Kg)

On Earth the force on the ground would be

F=mg
=100kg x 9.8m/s2
=980 Newtons.

About the same. So if this 100kg mass on the platform was a man he would feel roughly the same as he does on Earth (eg 1g).

To be precise he would be experiencing 10/9.8 = 1.02g

haruspex said:
The kg is a measure of mass, not force. Weight is a force. So a "weight of 100kg" is scientifically incorrect. It is used in everyday speech to stand for "the force exerted by gravity at the Earth's surface on a 100kg mass", but in scientific terms that's (approximately) 1000 Newtons. Likewise, the force required to accelerate a 100kg mass at 10m/s2 in a weightless environment is 1000 N.

So if this happened on Earth ignoring air resistance would the person on the platform feel weightless?
 
What might be confusing is that weighing scales measure the force an object puts on them so they should really be marked in Newtons not Kg. However since we don't normally take weighing scales to the moon they are calibrated for g=9.8 and marked in kg.

If you took kitchen weighing scales to the moon with a 1kg test mass you would discover they would read INCORRECTLY. For example they would under read by a factor of six yet the mass has not changed.
 
raeshun said:
So if this happened on Earth ignoring air resistance would the person on the platform feel weightless?

EDIT: haruspex is correct below. If the platform was on Earth and accelerating upwards at 10m/s2 then would feel about 2g.
 
Last edited:
raeshun said:
So if this happened on Earth ignoring air resistance would the person on the platform feel weightless?
If by "this" you mean the platform accelerating upwards at 10m/s2, they would feel a force of about 2g: 1g to stay put plus another to accelerate upwards.
 

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