Which is the best evidence that the United States has a federal system of government? Brinlist i will give

(**i would really appreciate if this was answered soon** ) which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

Which of the following changes will increase the capacitance of a parallel-plate capacitor? (there could be more than one correct choice.) a) increase the charge on the plates b) decrease the poten5al between the plates c) increase the potential between the plates d) introduce a dielectric material between the plates e) decrease the separation between the plates

This is the number of complete movements of a wave per second.