# Is the earth smoother than a ball bearing if the ball bearing were the same size as planet earth?

I thought i saw something on the Discovery channel about how the earth is smoother than a ball bearing of relative size, but i cant find any information anywhere. Does anyone have any help or websites where this can be found?

Relevance

Maybe!

The tallest mountains are less than 7 miles high.

So, the diameter of the earth is about 8000 miles.

Therefore the tolerance is less than one part in 1000.

If the earth were a 1 cm ball, that means that the tolerance is 10 micrometers.

The range of rated tolerances in ball bearings is typically for 0.5 to 4 micrometers. So the bearings are a bit smoother, but not much!

Now, if you count the *average* smoothness of the earth (including the flat oceans), this puts the smoothness of the earth in the range of ball bearings.

• Anonymous

Certainly not. The Earth has irregularities of 4 miles up or down on a diameter of 8000 miles, which is only 1 part in 2000. Well-finished ball bearings are smooth to 1 part in 6000, or even 1 in 40,000 for the very best grades available.

A billiard ball is a whole lot rougher, and probably comparable with the Earth.

• Anonymous

I haven't seen this program, but it doesn't make sense. Mount Everest and the entire Himalaya range extend more than 4 miles above the surrounding plains. Even if you shrank the Earth to the size of a ball bearing, or vice-versa, I would think there would be some roughness and texture to the surface, unlike a ball bearing, which is visibly very smooth.

Another example would be Mars. Its mountain, Olympus Mons, seen from space, is like a pimple on the surface of Mars. It actually sticks out above Mars' thin atmosphere into space. Granted, Olympus Mons is over 80,000 feet high, but Everest is close to half that.

• Anonymous

I know that if the earth were the size of a cue ball, the earth would be smoother. I don't know about a ball bearing.

The earth would be much smoother.

The precision of a ball Bering may be less than 1-20,000 of an inch the earth is much smoother!

The Earth is moslty water. Water has a lower density than a stainless steel ball bearing. Since when did water become smoother than steel ? Say you could turn the Earth into a basketball sized ball and a ball bearing as well. Then if you ran your fingers over them. What would happen as you ran your fingers over the Earth ball ? Water,ice,lava,sand,soil and people and animals would fall off. Don't forget about buildings and cars.

• Anonymous

It's smoother than a billiard ball, if that's what you're thinking of...

Check out the link below, particularly the 2nd-last paragraph.

I don't know about a ball bearing, but rounder than a billiard ball for sure.

• Anonymous
4 years ago

Jeff Moore and Mike Roberts asked the same question. You should read their answers side by side.

• Debra
Lv 4
4 years ago

It could just be a pimple of some kind. dont panic too much, but you really should get yourself to the doctor mate. I know its embarrassing, but better safe than sorry!