Final answer:
Air resistance on a skydiver is influenced by factors such as the skydiver's cross-sectional area, body orientation, air density, and clothing equipment roughness. Terminal velocity is reached once air resistance balances the force of gravity, which is dependent on these factors.
Step-by-step explanation:
Besides speed, several factors affect the air resistance on a skydiver. These include the cross-sectional area of the skydiver, the shape and orientation of the body during free fall, the density of the air, and the roughness of the skydiver's clothing and equipment. When a skydiver jumps from an aircraft and begins to fall, they are affected by the acceleration due to gravity and by air resistance. Eventually, as they accelerate, they will reach a terminal velocity, a point where the force of gravity is balanced by the force of air resistance and their acceleration decreases to near zero. For instance, a skydiver with a mass of 75 kg achieves a maximum terminal velocity of about 350 km/h in a headfirst position. This is due to minimizing the area and hence reducing drag. Conversely, in a spread-eagle position, the terminal velocity may decrease to about 200 km/h since the effective area, and therefore the drag, increases. Opening the parachute further decreases the terminal velocity as it greatly increases the area exposed to air resistance. Therefore, changing body positions and equipment during the skydive significantly changes air resistance and terminal velocity.