When rolled down a mountainside at 7. 0 m/s, the horizontal component of its velocity vector was 1. 8 m/s. What was the angle of the mountain surface above the horizontal?.

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