(4 pts) A bicycle pump has a barrel 65 cm long. On the upstroke, air is drawn into the pump at a pressure of 1 atm. On the downstroke, the air in the barrel is compressed. How long must the downstroke be to increase the pressure of the air in the barrel to 4 atm

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.

your answer is, orbit around the nucleus

cancer risk hope this

im srry but ur wrong the answer is d a smooth rock, some red dirt, and an empty bird's nest.