what is the net force on 4-kg falling object that requires 12-N of air resistance what is its acceleration

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.