How did hipparchus discover the wobble of earth’s axis, known as precession?

How do the kidneys affect homeostasis

The text compares alternating current with direct current. how are they different? a alternating current reverses direction in the electrical wiring. direct current flows in one direction only. b direct current reverses direction in the electrical wiring. alternating current flows in one direction only. c direct current is powered by solar energy. alternating current is powered by electrical energy. d alternating current does not move in the electrical wiring. direct current does move in the electrical wiring.

Why does a smaller car get better gas mileage than a bigger one?