Is Your 42 kg Scale Reading Accurate in Different Gravitational Fields?

  • Context: High School 
  • Thread starter Thread starter DrChem
  • Start date Start date
  • Tags Tags
    Machine Weighing
Click For Summary

Discussion Overview

The discussion revolves around the accuracy of weight measurements on scales in different gravitational fields, particularly focusing on the implications of mass versus weight. Participants explore how scales function and the factors that may affect their readings in various environments.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question whether a scale reading of 42 kg accurately reflects true weight, suggesting that it may vary depending on gravitational conditions.
  • One participant proposes that if a weighing machine is functioning correctly and under stable conditions, it should provide an accurate measurement of weight.
  • Another participant notes that real-world scales may underreport weight due to frictional forces, implying that the design of the scale could influence accuracy.
  • It is mentioned that certain scales, like food service and postal scales, have calibration features that may enhance measurement accuracy.
  • A participant clarifies the distinction between mass and weight, explaining that weight is dependent on gravitational force and provides a formula for calculating weight based on mass and gravitational acceleration.

Areas of Agreement / Disagreement

Participants express differing views on the accuracy of scale readings, with some asserting that scales can be accurate under ideal conditions, while others highlight potential inaccuracies due to design and environmental factors. The discussion remains unresolved regarding the extent to which scales can be trusted in varying gravitational fields.

Contextual Notes

Participants acknowledge that weight is influenced by gravitational fields, but there is no consensus on how this affects scale readings in practical scenarios. The discussion includes assumptions about scale functionality and environmental conditions that may not be universally applicable.

DrChem
Messages
5
Reaction score
0
if our weight is 42 kg in a weighing machine , in reality is it more or less than 42 kg?
 
Physics news on Phys.org


If a machine measures your weight to be 100 lbs, and the machine is not accelerating (at any rate, not accelerating quickly), and there are no extenuating circumstances, and the machine is well-oiled and frictional forces are neglible, and if the weighing machine measures correctly (that is, it doesn't measure the same weight differently depending on how much weight is already on it)... then I would say it's probably exactly right.

If the machine is more realistic, I guess it depends on how the machine's made.

I imagine most real machines get your weight a little low, due to frictional forces. Plus, they probably sell more scales that way.
 


Adding to the previous post, I know that some food service scales and postal scales have a zero weight calibration feature, which helps accuracy of a weighted measurement.
 


DrChem said:
if our weight is 42 kg in a weighing machine , in reality is it more or less than 42 kg?

"Mass" (represented in kg’s) refers to a “quantity of matter”. Therefore, our “weight” is merely a consequence of the gravitational field in which our mass is placed and then “weighed”.

On the moon, we‘d weigh roughly 6 times less than on the surface of the Earth, but our “mass” would be identical in either location, just as our “mass” would remain identical if we were placed anywhere else in the universe.

Weight is therefore defined by:

w = mg

where,

weight (in Newtons) = mass (in kg) x gravity (in m/s^2, which is 9.8 m/s^2 on Earth)


For instance, if your “mass” were 42 kg, on Earth you’d weigh:

42 kg x 9.8 m/s^2 = 411.6 Newtons (or 92.52768 pounds)


Pounds = .2248 x Newtons
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
1K
  • · Replies 9 ·
Replies
9
Views
3K
  • · Replies 206 ·
7
Replies
206
Views
8K
  • · Replies 29 ·
Replies
29
Views
4K
  • · Replies 15 ·
Replies
15
Views
3K
  • · Replies 10 ·
Replies
10
Views
70K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 59 ·
2
Replies
59
Views
7K
  • · Replies 5 ·
Replies
5
Views
2K