What is meant by a “conservation law"? What conditions are necessary in order to say that a system is obeying such a law?

Madison lives near the ocean. she’s formed a hypothesis that increased concentrations of salt in the air speeds the corrosion of certain metals. if madison plans to test this hypothesis, she will have to deal with the following variables in her experiment: dependent variable: independent variable: one possible confounding variable:

If we compare the force of gravity to strong nuclear force, we could conclude that

Q1=-2.00x10^-5 c, q2=+3.80x10^-6 c, q3=+5.30x10^-5 c. what is the electric potential energy for charge q2? between q1 and q2: 1.15m between q2 and q3: 2.88m