PLEASE HELP ME THIS IS 7TH GRADE SCIENCE I NEED THE HELP Write a short paragraph on this concept: You are a superhero that invented a machine that can control gravity (make it stronger or more weak). Tell about why you made it and the kinds of things you would use it for (you must include one way you would use it to increase gravity and one way to weaken gravity) and why you would do it.

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