When plane progressive waves travelling in the same direction superpose over each other then the velocity of resultant wave

Define progressive wave or a travelling wave.

Show that when two progressive waves travelling in the same direction superimpose,the resultant was is also a progressive wave.

A plane progressive wave cannot be represented by

Two waves travelling in mutually opposite direction in a medium superimpose over each other, then which event is observed -

When simple harmonic progressive waves, travelling through a medium each succeeding particle

Two identical sinusoidal waves each of amplitude 10 mm with a phase difference of 90^(@) are travelling in the same direction in a string. The amplitude of the resultant wave is

Two identical sinusoidal waves each of amplitude 10 mm with a phase difference of 90^(@) are travelling in the same direction in a string. The amplitude of the resultant wave is

Two progressive waves y_(1) = 4 sin 400 pi t and y_(2) = 3 Sin 404 pi t moving in the same direction superpose on each other producing beats. Then the number of beats per second and the ratio of maximum to minimum intensity of the resultant waves are respectively