Students in Ms. Owen’s class were assigned a task: model some part of the stimulus-response system in the human body. Sarah and Jose used the toy shown in the diagram to model one stimulus-response function of the nervous system. The ball rolls down the top ramp, then drops into the ramp below it and continues to roll.
Which function of the nervous system does the model BEST explain?
A) how the signal from a nerve in the skin reaches the brain
B) how the brain causes a gland to become more or less active
C) how the brain and spinal cord make up the central nervous system
D) how the nerves of the body can act together to produce movements

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

1 is a answer of a question