P2.10 Terminal velocity

• What is terminal velocity?

  Velocity remains constant with no acceleration
• What happens when a person steps out of an airplane?

  They experience a downward force due to gravity
• What force is felt as weight?

  The force of gravity acting on mass
• What remains constant for a person falling from an airplane?

  The magnitude of their weight
• What is the resultant force when a person first steps out of the plane?

  It is equal to the weight acting downwards
• What happens to the person as they start falling?

  They accelerate downwards due to resultant force
• What force opposes the weight during a fall?

  Air resistance acting upwards
• What causes air resistance?

  Collisions with tiny air particles
• What factors affect the size of air resistance?

  Surface area and velocity of the person
• How does surface area affect air resistance?

  Larger surface area increases air resistance
• How does velocity affect air resistance?

  Higher velocity increases air resistance
• What happens to air resistance when the person accelerates?

  Air resistance increases as velocity increases
• What happens to the resultant force as air resistance increases?

  Resultant force decreases as air resistance increases
• What does a velocity-time graph show as the person falls?

  The graph becomes less steep as acceleration decreases
• What occurs when air resistance equals weight?

  Resultant force becomes zero, no acceleration
• What is the term for constant velocity during free fall?

  Terminal velocity
• What happens when a parachute opens?

  Surface area increases, air resistance increases
• What happens to the resultant force when a parachute opens?

  Resultant force becomes upwards, causing deceleration
• What happens to terminal velocity with a parachute deployed?

  New terminal velocity is lower than before
• What are the key points about falling objects and terminal velocity?

  • Weight is the only force initially acting downwards.
  • Air resistance increases with velocity and surface area.
  • Resultant force decreases until it equals weight.
  • Terminal velocity is reached when forces balance.
  • Opening a parachute increases air resistance, lowering terminal velocity.
• What happens to the resultant force when an object reaches terminal velocity?

  Resultant force becomes zero
• What is the effect of air resistance on a falling object?

  It opposes the weight and slows the fall
• What happens to the acceleration of a falling object as it approaches terminal velocity?

  Acceleration decreases until it reaches zero
• When you let go of an object, why does it fall towards to the ground?

  Gravity exerts a force called weight on the object, which causes it to accelerate towards the earth, and so move downwards.
• What is terminal velocity?


  Terminal velocity is the maximum velocity attainable by an object as it falls through fluid (either a liquid or gas)
• What is the resultant force of an object falling at terminal velocity?


  The resultant force of an object falling at terminal velocity is zero.
• What causes air resistance?


  The force of air resistance is caused by a moving objects colliding with the particles in the air.
• Which two forces are in balance when a falling object reaches terminal velocity?


  Weight and air resistance will balance and (and cancel each other out)
• Why do falling objects reach terminal velocity?


  1. As an object accelerates and its velocity increases, the force of the air resistance will also increase.
  2. At some point, the force of weight acting downwards will equal to the air resistance upwards, so there will be no resultant force.
  3. This means that there will no longer be any acceleration and the velocity of the object will stay constant.
• What happen to weight and air resistance when a falling parachuter opens their parachute?


  The weight stays the same but the air resistance increases.
• The force that causes an object to fall towards the earth is:

  Weight
• The size of the air resistance is dependent on the object's ______.


  surface area and velocity
• The force of air resistance is caused by the moving object colliding with particles in the air.
• As the velocity of a falling object increases, the air resistance:


  Increases
• We say an object has reached 'terminal velocity' when it is falling with a _________ velocity.


  constant
• Terminal velocity is reached when:


  1. The weight has the same magnitude as the air resistance.
  2. The resultant force is zero.
• If a ball is dropped from a plane and has not yet reached terminal velocity, then the ball must be:


  Accelerating, The balls weight must still be larger than its air resistance, and so it will be accelerating.