This distance is known as the amplitude of the wave, and is the characteristic height of the wave, above or below the equilibrium position. Normally the symbol A is used to represent the amplitude of a wave. The SI unit of amplitude is the metre (m).
Most of the radiation, however, is absorbed by the earth's surface. ... Every surface on earth absorbs and reflects energy at varying degrees, based on its color and texture. Dark-colored objects absorb more visible radiation; light-colored objects reflect more visible radiation.
The answer to this is easy once you look at the units for Joules. 1 Joule = 1 N.m (Newton.meter). The 'Newton' is the units of force that we are trying to find, and we know the meters is 2, from the question. So you have an 8Joule or 8N.m energy difference over 2 meters.
well if we know the meters, then the real question is written as:
8N.m = ?N x 2m
so just solve for N;
N = 8N.m / 2m = 4
So F = 4N