# A long jump

A long jump of the master of parachuting, begins at an altitude of about 10 km. Only after flying a significant part of the way, he pulls the ring parachute and the last hundred meters goes down, hovering on his umbrella.

Many people think that by making a long jump, a person flies down, as in an empty space. If it were so, if the human body was falling in the air, like in a vacuum, a protracted jump would last much less than in reality, and the speed developed towards the end would be enormous.

However, air resistance prevents the increase in speed. The speed of the parachutist's body, performing a protracted jump, only grows within the first ten seconds, during the first hundred meters. The air resistance increases with increasing speed so much that quite soon a moment comes when the speed no longer changes.

Movement from the accelerated becomes uniform. It is possible by means of calculations to describe in general terms a protracted jump from the point of view of mechanics. Accelerated fall of the paratrooper lasts only the first 12 seconds or slightly less, depending on its weight. For this ten seconds, he manages to drop meters by 400-500 and get a speed of about 50 m per second. The rest of the path to the opening of the parachute is already passed through a uniform motion with this speed.

Rain drops fall about the same way. The only difference is that the first period of the fall, when the speed is still growing, continues for a raindrop just for about one second and even less. The final speed of the rain drops is therefore not so great as in the paratrooper demonstrating a protracted jump: it ranges from 2 to 7 m per second, depending on the size of the drop.