When falling through the air, which of the following objects will hit the ground first?

a penny
a large poster
a shoe box
a cell phone

from a very very very high point, the object that is more streamlined and has more mass would touch the ground first (phone), because of drag, but from a normal height, for example, 6 feet, the difference would be so small that the penny, the box and the phone would touch the ground at the same time

Explanation:

This is a little more complicated that what it seems. In the vacuum, all objects would hit the ground at the same exact moment, because we would not have the effects of drag.

But the problem states that the objects are falling through the air, so there is drag involved. Drag is a friction force that acts against the force of gravity, and it increases according to the surface area of the object parallel to the floor, like parachutes for example.

In this case, the poster would act like a parachute and increase drag, thus falling last.

The second to last would be the shoe box, since its surface area would be bigger than either the phone or the penny.

To compare the penny and the phone we would need to look a the definition of terminal velocity, which is the speed of the falling object at the point where the drag and the gravitational force cancel themselves. At this point the more streamlined the object is, the higher its terminal velocity, yet the mass would play a part too, let's say the cellphone is is 100 times heavier than the penny, if the cellphone also experiences 100 times the drag force as the penny (at a given speed), then their terminal velocities will be the same, then they would touch the ground at the same time.

So the conclusion is this: if you drop them from a very very very high point, then the heaviest and more streamlined object would touch the ground first, meaning the phone, but if you drop them from, let's say, a table, they difference would be so small that it would not really matter and the phone, the penny and even the box, would hit the ground at the same time.