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 thing S : 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