Sneaky little buggers(http://www.telegraph.co.uk/earth/earthnews/9699330/Ash-dieback-mistaken-for-squirrel-damage.html) — Sneaky little buggers
(http://www.telegraph.co.uk/earth/earthnews/9699330/Ash-dieback-mistaken-for-squirrel-damage.html)

You've probably come across a squirrel at some point in your life.

Those furry little hyper-energetic creatures that dart hither and tither like a cat chasing a laser pointer. You know what I'm talking about.

Infamous for scurrying about in search of nuts to nibble on, most squirrels are tree dwelling species, and reside at significant heights.
With the advent of urban architechture, squirrels have also taken to bunking in urban homes and attics, settling on roofs and terraces, much to the annoyance of some of it's occupants.

But constantly living and scurrying about at heights has its dangers - specifically falling.
Now most mammals dread falls, but squirrels seem to risk them all the time? Why? Surely falling is bad for them too, right?

Wrong.
Let's see why.

First we have to understand a bit about falling objects, and the physics behind them.
In middle/high-school class, you've had to calculate the velocity of an object falling from a certain height.
But out in the real world, we have to take into account something we consistently ignore in problems - Air resistance.

Any falling object has two forces acting on it while it falls.

Gravity
Aerodynamic resistance or Drag

But while the gravitational force is constant throughout it's fall, this drag increases with increase in (the square of) the velocity.

So as the velocity increases, there comes a point when the force of drag is equal to the pull of gravity.
Since the net force on the body is zero, the body will move at a constant velocity.
This constant velocity is special for any falling body, and is known as its terminal velocity.

No object will fall faster than it's terminal velocity, no matter what height it is dropped from.

Now, back to cute furry little things.
Squirrels, since they are small and light, means they have comparatively little pull from gravity, and since they have stretchy bodies and puffy tails, they experience a lot of drag. This means that their terminal velocity is actually quite low, and squirrels can survive impacts of that velocity.
ringing it all together. Terminal velocity is the fastest that an object will ever fall, no matter what height it is dropped from. Squirrels (unlike most other mammals) can survive impacts at their terminal velocity.

I believe I can fly.... (http://www.stephaniegallman.com/2010/05/day-186-unwelcome-house-guest.html) — I believe I can fly....
(http://www.stephaniegallman.com/2010/05/day-186-unwelcome-house-guest.html)

Which means no matter what height you drop a squirrel from, it will probably survive.
Though don't try flinging squirrels out of buildings just yet.