3. What would happen if Earth did not rotate?

If Earth were to stop spinning on its axis, gradually the oceans would migrate towards the poles from the equator.  The atmosphere would still be in motion with the Earth's original 1100 mile per hour rotation speed at the equator. And this means, rocks, topsoil, trees, buildings,  and so on, would be swept away into the atmosphere.

Hope that helped <3

To create standing waves, the length of the cavity should be:
L = nλ/2
λ = 2L/n , where n is a natural number
You should insert the value of L into this equation and then substitute different values of n, starting from 1 and increasing by 1 everytime, to obtain frequencies that lie within the given range.