what does gravity depend on?
a good rod is a Shakespeare ugly stick, durable and sensitive for a low price. A good reel for 50$ is a field and stream Rainer 30. These are for fresh water of course
A class B extinguisher is usually a compressed dry chemical, where a class A is water. Using a class B on a class A fire may work but it would tend to scatter the fire which may cause greater danger depending on the surroundings. Besides, with the cost of re-charging, it makes better sense to use the right tool for the job.(water is a lot cheaper to replace than the dry chemical)
That's kind of a broad question. I wouldn't even worry about curved space time (the idea that freefalling objects don't curve under gravity, they move straight and gravity is a bending of the space) until you understood a bunch of concepts some simple examples of general relativity issueslike light bending in an accelerating rocket, like time dilation between the top and bottom of the rocket, like the equivalence of gravity and acceleration (so light bends and time runs funny in gravity). Start with the . If you want to learn, I'd recomment James Hartles book on Gravity. It's user-friendly enough that an undergraduate who understands SR can pick it up and read the first 7 chapters and understand the basics of GR.
