(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

An amonia NH3 molecule in the figure has three hydrogen atoms, which form a equilateral triangle as the base of a pyramid. At the top of the pyramid is the nitrogen atom.

The length between any two hydrogen atoms is 9.4x10^-11, the length from nitrogen to any of the hydrogen atoms is 10.14x10^-11.

The mass ratio of nitrogen to hydrogen is 13.9.

The xaxis runs through the bottom of the pyramid, one of the points lies on it. The y axis runs through the center of the pyramid vertically.

2. Relevant equations

3. The attempt at a solution

I am getting a close answer, but off enough to think I'm doing something wrong.

x center of mass is 0, by symmetry/intuition.

For y, what i did was try to find how high nitrogen is with the pythagorean theorem. I got that nitrogen should be at a height of 3.8x10^-11 along y axis.

I multiplied this number by 13.9, then divided by 16.9.

My result is 3.125x10^-11 for the ycom, but the correct answer is 3.08x10^-11. Why am I off by that amount?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Center of mass of NH3 molecule, not quite there

**Physics Forums | Science Articles, Homework Help, Discussion**