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https://studentshare.org/miscellaneous/1602328-skydiving.
The reason behind this is the force of gravity. This gravity results in an acceleration of 9.8 m/s^2. Given this acceleration, the following formula determines how far the skydiver will travel in a given time:
X = Vi * t + .5 * g * t^2
where X is the distance traveled, t is the time and g is the acceleration due to gravity. (Lenaker 2002).
Air resistance is the force that acts against gravity while the skydiver is accelerating downward. Air resistance acts upwards against gravity which acts downwards. In the beginning, the push provided by air resistance is much smaller than the pull of gravity; therefore, the skydiver continues to accelerate downwards. However, as the skydiver falls faster and faster, the value of air resistance increases because of which the acceleration starts to decrease. Eventually, the force of air resistance becomes equal to that of the force of gravity. At this point, the skydiver stops accelerating and attains a constant speed. This constant speed is known as the terminal velocity. Terminal velocity is the maximum velocity that a particular body can reach when falling through the air. (Gordon et al 2000; Lenaker 2002)
The cross-sectional area of the skydiver plays a very important role in how quickly or slowly the skydiver will reach its terminal velocity. This is because the cross-sectional area determines the amount of air resistance that will act on the skydiver. The greater the cross-sectional area, the greater will be the force of air resistance. For example, a skydiver who falls in a spread eagle position will encounter a greater air resistance than one who falls head, or feet, first. This is where the role of parachutes comes in. As soon as the skydiver opens their parachute, their cross-sectional area increases, leading to an increase in the air resistance. This air resistance becomes greater than gravity. The upward net force causes the skydiver to slow down. As the speed of the skydiver decreases, so does the air resistance, until the skydiver reaches terminal velocity again. (Gordon et al. 2000).
As we can see, behind this energetic sport lie some complicated concepts of physics that enable us to fully enjoy it and experience the addictive rush of adrenaline that this sport provides!
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