URGENT!! What occurs when the trough of one light wave meets the crest of another lightwave?

destructive interference

constructive interference

wave building

wave destruction

Abaseball is thrown a distance of 20 meters. what is its speed if it takes 0.5 seconds to cover the distance

Electric charge is uniformly distributed inside a nonconducting sphere of radius 0.30 m. the electric field at a point p, which is 0.50 m from the center of the sphere, is 15,000 n/c and is directed radially outward. what is the maximum magnitude of the electric field due to this sphere

Matt is driving down 7th street. he drives 150 meters in 18 seconds. assuming he does not speed up or slow down, what is his speed?