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 object’s 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