Can some one with this question? "what is the relationships between. the force due to friction and the force due to gravity? is it true for all four surfaces? (wood, rubber, carpet, and sandpaper)

Okay, so let's start off with the difference between the force of friction, and the force of gravity.
Friction, is when two things rub against each-other. (Such as tectonic plates.)
Gravity, is something being held down towards the center of the earth.
(They are both caused by forces.)

Let's imagine wood is being rubbed against your hand. It isn't very comfortable, yet it moves evenly over your skin.
Now, let's use rubber. The skin on your hand is moving back and forth, along with the rubber.
Carpet. This is moving over your skin, yet causing some irritation.
With sandpaper. It is moving over your hand slightly like the rubber was, except this is trying to shape your hand, so therefore it is causing irritation.

I hope this helped in some way. May not have been the exact thing you wanted, but this should help give you an idea. (:

1) when you rub your hands together quickly, the kinetic energy is converted to mechanical energy.2) thermal energy from the sun travels to earth as infrared waves.3) energy is transferred through the matter of space by electromagnetic waves. 4) when a match is burned, chemical potential energy is converted to thermal and radiant energy. 5) seismicwaves are caused by back and forth movement , or vibration, of an object. 6) mechanicalenergy in an engine changes thermal energy into kinetic energy to make a car move.

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