A sound pulse sent vertically downwards into the earth is reflected from two different layers of the earth such that echoes are heard 1.2s and 1.4s. Assuming speed of the pulse is 2000ms-1, calculate the distance between the layers.
A string is stretched between two points 50cm apart. It is then plucked at its center and the velocity of the wave produced is 300m/s. Calculate the number of vibrations made by the string in 1s.
