# 1.is blowing of wind a wave motion?if not,which type of motion does it represent? i think that blowing of wind is not a wave motion b/c here particles of medium has displacement.2. show that particle speed can never be equal to wave speed in a sine wave if amplitude is less than wavelength divided by 360 degree.3. two wave pulses identical in shape but inverted with respect to each other are produced at two ends of a streched string.At an instant when pulses reach the middle,string becomes completely straight . what happens to the energy of two pulses? sir, i know that for a travelling wave,energy is not conserve b/c source continiously provide energy. but for a pulse,energy is conserve.

Grade:12

## 1 Answers

Ashish Kumar
askIITians Faculty 32 Points
10 years ago
A1) The wind motion is not a wave motion as the medium particles are not oscillating about their mean position but are themselves moving from the high pressure to the low pressure region.There is a net movement of the medium particles which is not caused by an oscillating source but by pressure differences,coriolis effect, and diiferenatial heating on earth , so it cannot be a wave motion.
A2 ) The maximum particle speed in a sine wave, Vp(max)=Aw
w=2pf =2p v/?
Vp(max) = A2p v/? v is the wave speed
Given that A < ?/2p or A 2p /? < 1
therefore Vp(max) < v, as Vp(max) is the maximum particle speed ,particle speed can never become equal to the wave speed .

A 3) When the wire becomes straight , the potential energy for the two waves becomes zero but the kinetic energy of the two waves will be maximum at this point .The potential energy is due to the position of the particles which are at their mean positions and the total energy of the two waves will be comprising only of kinetic energy .The displacement has become zero not the velocity .

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