How do intrusive rocks form?
lava cools slowly outside a volcano.
magma cools slowly inside a volcano.
molten material is cooled quickly by water.
magma is ejected into the air and cools slowly.

That is true it is called an aftershock

Wind speed, 2. length of time the wind has blown, 3. fetch. period of the wave;   answer . given a wave f(x, t), we call period t the interval of time we need to wait before the form of the wave is repeated. obviously, we must choose a constant x and observe the wave passing trough it. for exemple, for. f(x, t) = e i(kx - wt) . it's. f(x, t + t) = e i(kx - w(t + t)) ,. so that we have. 0 = f(x, t + t) - f(x, t) = e i(kx - wt) (e -iwt - 1) â e -iwt = 1 â t = n 2ï/w,. with n element of z. if we are considering two near peaks of f (that is a good way to define t) n = 1, and we have the famous. t = 2ï/w..hoped i !