# Skydiving gravity of the earth. As the skydiver jumps,

Skydiving is a sport/hobby that involves every one of Newton’s 3 laws. From lifting off in the plane to landing back onto Earth’s surface physics play a part in everything. The amount of forces acting on your body while skydiving are numerous. Gravity and air resistance are the most notable since you can physically feel the effects on yourself. Gravity is basically a force pulling all matters in the universe near the earth towards the earth. The force of gravity acting on an object falls as the distance between the earth and the object increases. Nevertheless the force of gravity on the ground is not very different from the height at which skydivers start the diving. Just assume the effect of gravity on the skydiver is a constant force of 9.81m/s2 pulling the skydiver towards the earth. Without the force of gravity the skydivers wouldn’t be able to reach the ground. Instead of falling they would travel the same speed and path as the plane they jumped from. Before the skydiver jumps, they sit in the plane.  The upward force of the plane balances the gravity of the earth. As the skydiver jumps, there is no more upward force from the plane to offset the force of gravity.  The force of gravity immediately pulls the skydiver towards the earth. According to Newton’s first law, the velocity of an object remains constant unless the object is acted upon by an external force. The skydiver starts to accelerate towards the earth as gravity acts upon the skydiver. As the skydiver starts to accelerate, the air resistance or drag force starts to grow and acts in an opposite direction. The force of air resistance will offset some of the force of gravity. A smaller net downward pull force acting on the skydiver means a smaller downward acceleration. This doesn’t mean that the skydivers will slowdown; it means that the skydiver’s velocity will add up more slowly. Without air resistance the skydivers would plummet into the earth’s surface at fatal speeds despite deploying their parachute. Eventually at some point of time, as the air resistance grows, it is just enough to offset the gravity. According the Newton’s second law once this point is reached the net force equals 0N meaning no acceleration. That doesn’t mean that the skydiver will stop falling; it means the skydiver will continue falling at a constant velocity. Landing at this velocity will most likely result in death which is why skydivers come with parachutes.The opening of the parachute substantially increases the surface air can act on, resulting in a substantial increase in air resistance. Now the force of gravity is smaller than air resistance. The pulling force towards the earth becomes negative.  If the skydiver are falling at 50ms-1 the skydiver has an acceleration of 0ms-2, since the upward force is much bigger, the skydiver gets to have a negative acceleration. This doesn’t mean that the skydiver is flying upwards, but it means that the skydiver falls more slowly.When the velocity grows the air resistance grows too. Once air resistance has grown a lot,  the velocity slows down. The air resistance will decrease as the velocity has decreased. As the air resistance decreases, it will reach a point that the gravity will offset the air resistance. Now there will be no acceleration so the acceleration will return to 0m/s2 again. This doesn’t mean that the skydiver is floating in mid air, but it means that the skydiver will continue to fall at a constant velocity.At this time, the skydiver will likely be at a constant velocity meters again. After the landing, you will have a constant falling velocity of 0m/s again. When landing you exert a force onto the earth’s surface. According to Newton’s third law once you exert that force onto the surface the Earth gives an equal and opposite reaction onto you.