Air Resistance

1
Air Resistance
2
Air Resistance

• What two forces are acting on an object when it
  falls?
• Gravity
• Air resistance

3
Air Resistance

• Imagine dropping two pieces of paper. One is
  crumpled and the other is flat.
• Which one will reach the ground faster and why?
• The crumpled one because it has less surface
  area.

4
Air Resistance

• When something falls, air resistance acts in the
  opposite direction as the force of gravity.
• Air resistance acts in the opposite direction of
  the objects motion.

5
Air Resistance

• The amount of air resistance an object
  experiences depends on three thingS
• Speed
• Size
• Shape

6
Air Resistance

• Why do leaves, papers, and feathers fall at
  different speeds than acorns, pens, and glasses?
• Because of Air Resistance
• Air resistance not mass is responsible for the
  difference in objects falling speed.

7
Terminal Velocity

• As an object falls, it accelerates and its speed
  increases.
• The force of air resistance increases with speed.

8
Terminal Velocity

• The force of air resistance increases until it
  becomes large enough to cancel the force of
  gravity.
• When the forces cancel each other out the object
  no longer accelerates.
• The object then falls at a constant speed called
  terminal velocity.

9
Terminal Velocity

• Terminal Velocity is the highest velocity that a
  falling object will reach.
• A low terminal velocity allows the skydiver to
  land safely.

10
Terminal Velocity

• Why would a skydiver want to lay out flat versus
  falling standing up?
• Think about our paper example crumpled vs flat