Does grass absorb the sun's energy?
Indeed it does, and by the process of photosynthesis, it converts the CO2 from the air, and the Hydrogen from the water into complex carbohydrates. The chemical chlorophyll which enables this process is green in colour.
Example: the grass makes energy from the sun. A zebra eats the grass so now the zebra has the suns energy. A lion comes along and eats the zebra so now the lion has its own energy, the zebras energy, and the energy the grass made. So all that energy came from the sun. That kind of makes sense and kind of doesn't.
Several reasons, for one the sidewalk is flat and acts as a better surface to directly absorb the suns energy. Second because the sidewalk a solid object it reacts to heat quicker than a substrate such as soil does. If you were to try the same thing on a cool night. You'd find the sidewalk was colder than the surrounding grass. radiation apex =3