PLEASE HELP I DONT GET HOW TO ANSWER... • If we did use zero-friction machines for these purposes, how would our everyday lives change?

the world would just slide forever

Explanation:

A frictional force exists when two objects come in contact with each other. It opposes motion, meaning if something is sliding on the floor, friction is the force that makes it eventually come to a stop. In a world without friction, the object would continue to slide forever, if not acted on by another force.

the results is a decrease in air temperature with an increase of altitude.

explanation:

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.