Terminal Velocity

What is terminal velocity?


When the velocity of something remains constant with no acceleration

What happens to an object (person) when it first steps out of an airplane?


It experiences a downward force due to weight

What force pulls a person downwards when falling?


Gravity, which is shown as weight

What happens to the resultant force as a person starts falling?


There is a resultant force downwards because the person starts accelerating downwards

What force opposes weight during a fall?

Air resistance

What is another name for air resistance?

Drag

What factors affect the size of air resistance?


• Surface area

• Velocity of the person or object

How does surface area affect air resistance?


Larger surface area makes a larger area for collisions to take place

How does velocity affect air resistance?


The faster the person is moving, the more particles they will collide with

What happens to air resistance when a person accelerates downwards?


Air resistance increases as velocity increases

What happens to the resultant force downwards (weight) as air resistance increases?


The resultant force downwards decreases as air resistance increases

What does it mean when air resistance equals weight? (give 3 details)

• Resultant force is zero

• There is no acceleration

• Terminal velocity has been reached

What is the term for the velocity when forces balance out?


Terminal Velocity

What happens when a parachute opens during a fall?


Surface area increases, air resistance increases

What happens to air resistance as the person slows down with a parachute?


Air resistance decreases as velocity decreases

What are the key things that would happen if a person fell/stepped out of from an aeroplane, and then afterwards opened a parachute?


• To begin with weight will be be the only force initially acting downwards, and will therefore be the resultant force

• Air resistance will increase with velocity

• As the air resistance increases the resultant force will decrease

• When the resultant force reaches zero, terminal velocity has been reached

• Opening a parachute would increase the surface area and therefore the increasing air resistance, this means there will no longer be terminal velocity until the air resistance decreases due to a decrease in velocity

• As velocity decreases and so does air resistance, the resultant force decreases and when it reaches zero the terminal velocity will have been reached again and this will continue until the person lands if there is no sudden changes.

What is the relationship between weight and air resistance at terminal velocity?


They are equal and opposite forces

How does the velocity-time graph illustrate the falling object's acceleration?


line on the graph becomes less steep as acceleration decreases