Gravity is a well-known concept, both from Alfonso Cuarón's eponymous 2013 Oscar-winning film and as one of the fundamental physical forces of the universe that governs our daily lives.
Gravity as a force does exist
What we think of as "gravity," though is actually a constant, a measurement of the acceleration of roughly 9.81 m/s2 that the Earth imparts on objects due to gravity. Gravity, as a physical force is actually one of the four fundamental forces that scientists have observed in the universe, along with electromagnetic, strong nuclear, and weak nuclear forces, and is both the weakest and least understood of the four. However, due to empirical observation, we can see that gravity as a force does exist, and even measure the force of that attraction. Newton’s famous law of universal gravitation, does just that, and states that everything in the universe attracts everything else with a force proportional to the product of their masses and inversely proportional to their distances. When an object falls on Earth, the Earth exerts a gravitational force on the object, pulling the object towards the Earth’s center of mass (and the object pulls back, but because it's a lot smaller than the Earth, that pull is almost imperceptible).
There’s still a lot we don’t know about gravity
The thing is, there’s still a lot we don’t know about gravity, which, while successfully integrated with Einstein’s general theory of relativity, still has issues in incorporating laws of quantum physics. We may never truly understand gravity, or how it works, or even be sure it will always continue to work that way, as time goes on and we ponder the vast and infinite mysteries of our universe.
Anyway, the UMi London is a rugged smartphone that uses toughened "Dual Glass" technology and double coated foam tape from 3M to offer what UMi claims is the "toughest dual protection smartphone" on the market.
UMi, ostensibly attempting to show off the durability of the London, dropped one off a building, graciously donating one of their phones to help to prove the aforementioned theorems as best as possible and ensure our peace of mind in the existence of physics.
A good estimate for the actual speed of the phone is around 40 miles per hour
Taking into account the height in question, the aforementioned gravitation constant for earth of 9.81 meters/second-squared, the physical dimensions of the phone of 4.52 x 2.28 x 0.34 inches, the mass of 0.160 kg, the density of air at 100 ft of 12.25*(10–1) kg/m3, and the coefficient of drag of a flat, perpendicular object being between 1.28–2.05, along with some applications of basic physics allows for the final terminal (maximum possible) velocity to range from between 38.98 feet per second as the absolute slowest speed and 161.876 feet per second at absolute fastest (depending on how drag is approximated) before it hits the ground. Considering that the phone, with no air resistance, would hit speeds of roughly 80.24 feet per second when dropped from 100 feet up, a good estimate for the actual speed of the phone is around 60 feet per second, or 40 miles per hour.
As can be seen in the video above, the phone in question did in fact fall to the ground, with the screen breaking upon impact (as glass, even "Dual Glass", is known to do when hitting things at speeds between 26.57 to 110.37 miles per hour) confirming for us all that a phone will still break when you drop it, and that gravity, for now, still exists. The phone, aside from the cracked screen, is still shown to be working in the video.