If a plane is traveling at a velocity of 100 km/hr East, and if the wind velocity is 25 km/hr to the East, then what is the velocity of the plane relative to an observer on the ground below?
100 km/hr East
75 km/hr West
75 km/hr East
125 km/hr East

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