Lesser the radius the lesser the volume. Why?

  • Context: Undergrad 
  • Thread starter Thread starter avito009
  • Start date Start date
  • Tags Tags
    Radius Volume
Click For Summary
SUMMARY

The discussion clarifies that the volume of a sphere is mathematically determined by the formula V = (4/3)πR³, establishing that a planet with half the radius of Earth possesses less than half the volume. Specifically, if the radius is halved, the volume and mass decrease to one-eighth of the original values. The relationship between dimensions and volume is geometrical, with a doubling of dimensions resulting in an eightfold increase in volume and mass, while halving dimensions leads to an eightfold decrease.

PREREQUISITES
  • Understanding of geometric volume calculations
  • Familiarity with the formula for the volume of a sphere
  • Basic knowledge of dimensional analysis
  • Concept of mass and gravity in relation to volume
NEXT STEPS
  • Study the mathematical derivation of the volume of a sphere
  • Explore the implications of dimensional scaling on physical properties
  • Learn about the relationship between gravity and mass in celestial bodies
  • Investigate geometric representations of volume using cubes and spheres
USEFUL FOR

Students of physics, mathematicians, and anyone interested in understanding the geometric principles governing volume and mass in relation to dimensional changes.

avito009
Messages
184
Reaction score
4
If we take two planets One Earth and another one with half the radius of Earth. The planet with half the radius has lesser than half of the volume of the Earth. Also given that mass is half. Why?

Is it because lower radius and lesser mass means lesser gravity and lesser gravity can pull lesser matter towards the core?
 
Physics news on Phys.org
Radius and volume of a sphere are related by [itex]V=\frac{4}{3} \pi R^3[/itex]. Its completely geometrical and has nothing to do with physics!
 
http://imgur.com/UKHLp4n

Doubling all dimensions means 8x the volume and mass. Halving all the dimensions means 1/8 the volume and mass.

Looking at these cubes in the image link should explain it very intuitively. If there are 2 cubes per side there are a total of 8 cubes. If there are 4 cubes per side, there are a total of 64 cubes.

Area is x*y so it's squared. Volume is x*y*z so it's cubed. Therefore a 2x increase in dimensions means 2*2=4 increase in area and 2*2*2=8 increase in volume (and therefore mass).
 

Similar threads

  • · Replies 0 ·
Replies
0
Views
2K
  • · Replies 29 ·
Replies
29
Views
3K
  • · Replies 7 ·
Replies
7
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 8 ·
Replies
8
Views
4K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 16 ·
Replies
16
Views
1K