Parachute Physics applying on

Parachutes.

Lucas Machado de Vasconcelos Physics 121- 6:30AM to 9:15AM

Principle of a Parachute

In theory the parachute help to slow the velocity down as the person which is operating and controlling it, the principle idea based on it is the air resistance which is also know as the Force Drag(Common Term Used in Physics).

What causes the Air Resistance? Even though the air is invisible when it

comes to resistance, the air is always present principally when we are talking about about highly speed.

A good example that can help us to completely understand this “invisible resistance is the water. When you dive on the “belly flop” style your velocity will slow down really fast because the resistance of the water will hold the person because the part of the body hitting the water will be big having a lot more buoyancy. Having that in mind the difference is that in the air the name will be air resistance instead of buoyancy, although the same idea continues, which means that more are horizontally falling less velocity than the same are vertically.

Terminal Velocity Without a Parachute When we are talking about

velocity we have to put in detail that a body falling from the sky can accelerate at a 10m/s^2 which means that after a minute and a half (90s ) the body will be falling about 1000 meters per second which approximately 3600km/h.

Although at practice after 5 seconds the body will reach a speed where the force of air resistance will balance the gravity and then it will be at balance , at this point it will be called Terminal Velocity(Velocity is constant)

How much does a parachute slow you

down?The parachute works increasing the area which will be in contact with the air getting a higher drag force, usually decreases 90% of the velocity and making the velocity of the person about 5m/s when the person is about to land.

How does parachute work in practice?

Parachutes are divide in 3 parts: Container ; Main and Reserve ; Pilot Chute.

Container: Is the backpack on which they put the all parachute “body”.

Main: Is the parachute itself, the big part that holds the weight.

Pilot Chute: Is the little parachute that kind of help the main one to open correctly.

Ripcord: The little cord that makes the parachute works.

Suspension Lines: Lines that give sustainability to the parachute.

All those parts had a main characteristics of holding the parachute, giving it sustainability and also slowing it down, in the other for it not to break and not cause any damage to the “pilot”.

Solving a parachute exercise with Physics. 1-105__Consider a parachute cruising in the air downward at a constant velocity of V0 starting at time zero at height of 20 meters above the ground; where h is the vertical distance of the parachute from the ground level, t is the independent variable time, and a is a constant. If it is known that the parachute hits the ground at time tf =8s , determine the value of the V0 and the a (acceleration).