Why do spheres roll easier than cubes?

  • Thread starter Thread starter Sundown444
  • Start date Start date
  • Tags Tags
    Rotation Shapes
AI Thread Summary
Spheres roll easier than cubes due to their shape, which allows their center of mass to remain at a constant height above the surface while rolling. This stability means less energy is required to maintain motion compared to cubes, which lose energy when pivoting around edges and experience energy loss through heat and sound upon landing. The discussion highlights that only minimal energy is lost to friction in spheres, making them more efficient for rolling. In contrast, cubes require additional energy to lift their center of mass after pivoting. Overall, the physics of motion favors spherical shapes for rolling efficiency.
Sundown444
Messages
179
Reaction score
7
I am aware that this could be the wrong section for this, but I wish to ask this here if you all don't mind. You all know how a sphere rolls along the ground easier than a cube, right? Well, how are the physics of motion involved in why a sphere rolls easier than a cube, or an irregular object?
 
Physics news on Phys.org
When a sphere rolls its centre of mass stays at a constant height above the surface.
 
MrAnchovy said:
When a sphere rolls its centre of mass stays at a constant height above the surface.

What about other shapes?
 
It doesn't (apart from a cylinder and similar shapes).
 
MrAnchovy said:
It doesn't (apart from a cylinder and similar shapes).

Well, if that is that, then thanks. I appreciate the help.

Wait, in the case of both spheres or other objects, the CoM still follows a straight line, right?
 
Yes I guess that's it - there's not much more to say really, except that moving the centre of mass of say a cube up and pivoting it around an edge takes energy; some of this energy is released when the cube "falls" over the pivot edge but then that most of that energy is lost in heat and perhaps sound when the cube lands on a face, then you have to put more energy into lift the centre of mass again...
 
MrAnchovy said:
Yes I guess that's it - there's not much more to say really, except that moving the centre of mass of say a cube up and pivoting it around an edge takes energy; some of this energy is released when the cube "falls" over the pivot edge but then that most of that energy is lost in heat and perhaps sound when the cube lands on a face, then you have to put more energy into lift the centre of mass again...

And there is less energy to be used in a sphere, right?
 
Only what is lost in friction.
 
Okay then. I get it now. Thanks.
 

Similar threads

B Questions about momentum and force as well as normal force/friction
Replies
35
Views
4K
I What is the Purpose of Torque?
Replies
7
Views
2K
Rotation of a sphere and cube full with water
Replies
3
Views
2K
Distinction between translational and rotational energy
Replies
1
Views
2K
Rotating Sphere: Conceptual Question
Replies
10
Views
3K
Why did the sphere in a potential well stop rolling sooner than expected?
Replies
8
Views
2K
Direction of friction acting on a rolling object
Replies
12
Views
10K
Two-body equation of motion resolution
Replies
7
Views
2K
B The physics of flywheel launchers (like tennis ball shooters)
2
Replies
60
Views
4K
Can a gyroscope lift a fulcrum (and itself), hinged to the floor?
Replies
8
Views
3K

Hot Threads

Recent Insights

Back
Top