Suppose u(x, t) measures the concentration of a substance in a moving stream (moving with velocity v). suppose the concentration u(x, t) changes both by diffusion and convection; derive the equatiorn from the fact that at any instant of time, the total mass of the material is not created or destroyed in the region [x, x + ax] hint write the conservation equation change of mass inside [x, x + ax] = change due to diffusion across the boundaries + change due to the material being carried across the boundaries

as we probably am aware that our atmosphere or air have various levels, each level has different gasses, and each gas has another porousness. at the point when the light originates from lower porousness to higher penetrability, it alters its course. with the goal that implies that when the light originates from the moon to the earth, it alters it's course a lot more occasions. it essentially implies that the state of the light piece of the moon is changed on the earth.

not copied too! hope this !

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h o h o hope you have a merry christmas!

answer(20) psi;