D. Free fall
Explanation:
An object is said to be in free fall when there is only one force acting on the body, which is the force of gravity.
Near the Earth's surface, the force of gravity acting on a body is given by
F = mg
where
m is the mass of the body
g is the acceleration of gravity (its value is 
)
The direction of this force is downward (towards the Earth's centre).
If we apply Newton's second law on an object in free-fall, we can find its acceleration. In fact, we have:
And substituting F,
So, every object in free-fall accelerates at towards the ground.
Learn more about free fall here:
brainly.com/question/1748290
brainly.com/question/11042118
brainly.com/question/2455974
brainly.com/question/2607086
#LearnwithBrainly
Answer:
Fricción.
Explicación:
Caminando con otro compañero al mismo tiempo y al mismo ritmo, el movimiento se produce debido a la fricción del suelo y la suela de los zapatos porque la fricción es la fuerza que ayuda en el movimiento de los objetos de un lugar a otro. Si no hay fricción entre el suelo y la suela de los zapatos, no podemos dar un paso por lo que podemos decir que la fricción nos mueve hacia adelante.
Carbon isn’t because all the others on the list are naturally made apart from carbon which is man made because of all the pollution . X
