Air Resistance and Falling Objects

Objects in Free Fall

• In the absence of air resistance and other external forces, all objects fall towards the Earth with the same rate of acceleration.
• This is because gravity is the only force acting on the object, and all objects experience the same acceleration in a vacuum.
• In a vacuum, a feather and a bowling ball would land on the ground at the same time if dropped from the same height.

Air Resistance

• Air resistance refers to the resistance encountered by an object as it moves through the air.
• It is also known as the friction experienced by an object as it encounters molecules in the atmosphere.
• Air resistance slows down the velocity of an object and its rate of acceleration.
• Two main factors that influence air resistance are:
  • Speed (velocity) of the object: faster speeds result in more air resistance.
  • Surface area of the object: increased surface area results in increased air resistance.

Terminal Velocity

• Terminal velocity is the point at which an object's acceleration is zero, meaning it is no longer accelerating.
• At this point, the force of gravity is balanced by the force of air resistance.

Free Fall and Air Resistance Force

• Free fall represents a type of motion in which gravity is the only force experienced by an object.
• Air resistance is negligible in free fall, and objects of different masses will accelerate towards the Earth at a rate of 9.8 m/s².
• In the real world, air resistance affects the acceleration of falling objects, causing them to slow down.

Newton's Second Law of Motion

• The Second Law of Motion examines how objects move when they are impacted by different external forces.
• The law states that an object's motion is influenced by its mass, external forces, and acceleration.
• The equation for the Second Law of Motion is: F = ma, where F is the net external force, m is the mass of the object, and a is its acceleration.

Air Resistance Formula

• The air resistance formula is: F_d = ½pv^2C_dA, where:
  • F_d is the force of air resistance
  • p is the density of the fluid
  • v is the velocity of the object
  • C_d is the drag coefficient
  • A is the cross-sectional area of the object
• The air resistance formula can be used to calculate the force of air resistance experienced by an object.