What do Kepler's laws describe? O A. The forces between any two objects
O B. The effect of mass on gravity
C. The reason gravity acts on mass
O D. The relationship between period and orbit size

Which statement best describes the superposition principle? a.) if two in-phase waves arrive simultaneously at a point, their amplitudes add up b.) if two out-of-phase waves arrive simultaneously at a point, their amplitudes add up c.) if two in-phase waves arrive at a point one after another, their amplitudes add up d.) if two out-of-phase waves arrive at a point one after another, their amplitudes adds up