This phenomenon is called Nuclear Magnetic Resonance.
When I met my future wife, she was working in the medical research building next door to the communications building where I worked. (We shared a parking lot.) MRI was not a thing yet, and she was doing research in Nuclear Magnetic Resonance. I learned a lot about it when I walked next door to visit her in her lab. Strange as it may seem, several years earlier, her older brother was involved in the invention of the CAT scan. When we got married, I figured that our kids had at least a 50% chance of inheriting some brains. So we had some, and they've done OK.
It is salt water because they are two things combined together.
Where Gravity rely's on only mass and distance and nothing else, so the weight on the planets will vary like you have stated. However Mars is smaller than Mercury, so the weight on Mars will be less, and the weight on Mercury will be more. Think this way.
More Mass = More Gravity = More Weight
Less Mass = Less Gravity = Less Weight
C standards are based on observable, reproducible natural phenomena.
<span>The angular momentum L of a rotating wheel with mass m, radius r, moment of inertia I, angular velocity ω, and velocity v of its outer edge:
</span><span>C) Iω</span>