30. Terminal Velocity

GCSE Physics: Terminal Velocity

Forces: When an object first starts falling (e.g., jumping out of a plane), Weight is the only significant force acting on it.
Weight: This is the force of gravity pulling the object toward Earth. Since mass remains constant, weight stays the same throughout the fall.
Resultant Force: At the very start, the resultant force is equal to the weight, acting downwards.
Motion: This large downward resultant force causes the object to accelerate rapidly.

Air Resistance (Drag): Caused by collisions with air particles. As the object falls, it bangs into these particles, creating an upward force.
Factors Affecting Air Resistance:
- Velocity: The faster the object moves, the more air particles it collides with per second, increasing the drag.
- Surface Area: A larger area provides more space for collisions to occur.
Changing Forces: As the object speeds up, air resistance grows. Since weight remains constant, the resultant force decreases (Weight - Air Resistance).
Motion: The object continues to accelerate, but at a slower rate as the resultant force shrinks.

Equilibrium: Eventually, the object moves fast enough that the upward air resistance becomes equal to the downward weight.
Resultant Force: The forces are now balanced, meaning the resultant force is zero.
Motion: According to Newton's laws, with no resultant force, there is no more acceleration. The object continues to fall at a constant speed, known as terminal velocity.

Surface Area Spike: Opening a parachute massively increases the surface area.
Resultant Force: Air resistance immediately becomes much larger than the weight, creating an upward resultant force.
Motion: The object decelerates (slows down).
New Terminal Velocity: As it slows down, air resistance decreases until it once again equals the weight. The object reaches a new, much lower terminal velocity, allowing for a safe landing.