Question: If I let a stone drop from a certain height and throw a stone from a certain height, with air resistance, which will reach the ground first? 
When I draw a free body diagram the air resistance in the y axis for the throw is smaller in magnitude compared to the free fall, and yet it is the free fall that reaches the ground first. Why is that?

[![enter image description here](https://i.stack.imgur.com/xesNn.jpg)](https://i.stack.imgur.com/xesNn.jpg)

Answer: 
First remember that Air resistance is proportional to $v\_{net}^2$. 

And $v\_{net}^{\text{freefall(1)}}<v\_{net}^{\text{throw at angle $\theta$ to normal(2)}}$

So air-resistive force acting in free fall proportional to $(v\_{net}^{(1)})^2$

And air-resistive force acting in the other case proportional to $(v\_{net}^{(2)})^2\cos(\phi) $ ($\phi$ is the angle made at that moment with normal)

So it might well happen that if you plug in values of $g$and other friction constants and velocities,$(v\_{net}^{(2)})^2\cos(\phi)> (v\_{net}^{(1)})^2$ in which case freefalling body comes to the ground first.
To clarify, movement in the X-direction is separate from movement in the Y-direction. Regardless of the fact that one pebble is moving horizontally, both experience the same downwards force of -9.8 m/s^2. Therefore, if they were released from the same height at the same time, one moving straight down and one moving horizontally, they would both reach the ground at the same time.