## A 70 kg Skydiver Descending with Constant Velocity
### Introduction
A skydiver is an individual who exits an aircraft with the intention of falling through the air before deploying a parachute to slow their descent. During the initial phase of their descent, before the parachute is deployed, the skydiver experiences a period of constant velocity. This occurs when the gravitational force acting on the skydiver is equal to the air resistance force acting in the opposite direction.
### Constant Velocity
An object is said to be in constant velocity when its speed and direction do not change over time. In the case of a skydiver, constant velocity occurs when the gravitational force pulling them downward is equal to the air resistance force pushing them upward. This results in a balanced state where the skydiver maintains a consistent speed and vertical position.
### Gravitational Force
Gravitational force is the attractive force between any two objects with mass. For a skydiver, the gravitational force is the force pulling them towards the center of the Earth. The strength of the gravitational force is directly proportional to the skydiver’s mass and the mass of the Earth.
### Air Resistance Force
Air resistance force, also known as drag, is the force acting on an object moving through a fluid (in this case, air). The air resistance force is proportional to the skydiver’s velocity squared and the air density. As the skydiver descends, the air resistance force increases due to the increasing velocity.
### Equilibrium
When the gravitational force and the air resistance force are equal, the skydiver reaches a state of equilibrium. In this state, the velocity and vertical position of the skydiver remain constant. This equilibrium is achieved at a particular velocity known as the terminal velocity.
### Terminal Velocity
Terminal velocity is the constant velocity reached by an object in freefall when the gravitational force and the air resistance force are equal. The terminal velocity of an object depends on its mass, shape, and air density. For a typical skydiver, the terminal velocity is approximately 195 km/h (121 mph).
### Factors Affecting Terminal Velocity
The terminal velocity of a skydiver can be affected by several factors, including:
– Body Shape: A skydiver with a larger surface area will experience greater air resistance and reach a lower terminal velocity.
– Clothing: Clothing can increase the surface area and drag, thereby lowering the terminal velocity.
– Equipment: Gear and equipment carried by the skydiver can also affect the terminal velocity.
### Conclusion
A 70 kg skydiver descending with a constant velocity experiences a force balance between gravitational force and air resistance force. This equilibrium results in a constant speed and vertical position, known as terminal velocity. Terminal velocity depends on the skydiver’s mass, shape, and air density. Understanding the forces acting on a skydiver is crucial for safe and successful skydiving.
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