**Ask a monkey a physics question thread**

[Savy]

Yeah I had to look up radians, I don't remember learning about that at school either. It's clear now how pi is intricately related to the angle of a sector.

And yeah reciprocal is incorrect, I think I can see from mojo's equation solving what the arcsine is relative to the sine. It's what multiplied is to divide.

You won't have done, doesn't get taught till a-level. Is just a way of measuring angles that makes life a bit easier for more maths related things.

Radians are used in math and physics. Degrees and Grads (100 grads = 90 degrees) are more common in engineering.

Grads is essentially a % of vertical-ness scale.

I've never seen someone use gradians in practise.

[OngBonga]

You won't have done, doesn't get taught till a-level. Is just a way of measuring angles that makes life a bit easier for more maths related things.

I can see how it's a useful measure of an angle. It's just I naturally think angles in degrees as naturally as I think words in English.

[OngBonga]

I've never seen someone use gradians in practise.

I would imagine it's useful in engineering and construction.

[MadMojoMonkey]

I've never seen someone use gradians in practise.

I would imagine it's useful in engineering and construction.

I have seen it used in civil engineering when discussing the slope of a roadway. Even then, only among other civil engineers. I very much doubt they would describe - say - a truss bridge using grads.

When I was hiking all over the US, we used grads. It probably had something to do with using a contour map to plot the hiking path, but I'm guessing. If I'm right, that's a pretty strong link to why they use it in roadways.

That's about it, though, for using grads.

The mathematical definition of slope (rise / run) is used in plumbing. I.e. you need a drop of 1/8 inch per foot on a "horizontal" drainage line (more if the drain carries solids).