Warm-up (pg. 24)

1. Warm-up (pg. 24) Thursday (9/26) • If a pebble and a sheet of paper are dropped at the same time from the same height, which one will hit the ground first? Explain your answer. Pick up the velocity and acceleration worksheet. That’s Homework!! Answer the question in a complete sentence.

2. http://youtu.be/-4_rceVPVSY • Galileo first introduced the concept of free fall. His classic experiments led to the finding that all objects free fall at the same rate, regardless of their mass. • Newton later took Galileo's ideas about mechanics and formalized them into his laws of motion.

3. Ball Action • Distance ball released from = _______ m • Copy table in your journal. • Watch student volunteer drop ball and record time it hit floor. Repeat 3 times. • What other data information can we list about the ball? • Calculate average time. • Calculate acceleration (Choose 1 of the kinematic equations).

5. Section 3 Falling Objects Chapter 2 Free Fall • Free fall is the motion of a body when only the force due to gravity is acting on the body. • The acceleration on an object in free fall is called the acceleration due to gravity, or free-fall acceleration. • Free-fall acceleration is denoted with the symbols ag(generally) or g(on Earth’s surface).

6. Section 3 Falling Objects Chapter 2 Free-Fall Acceleration • Free-fall acceleration is the same for all objects, regardless of mass. • The value is g= 9.81 m/s2. • Free-fall acceleration on Earth’s surface is –9.81 m/s2 at all points in the object’s motion. • Consider a ball thrown up into the air. • Moving upward: velocity is decreasing, acceleration is –9.81 m/s2 • Top of path: velocity is zero, acceleration is –9.81 m/s2 • Moving downward: velocity is increasing, acceleration is –9.81 m/s2

7. Terminal velocity The velocity at which the driving forces are cancelled out by the resistive forces. Air resistance Opposes the force of gravity

8. With air resistance With only gravity Free Fall

9. Terminal Velocity

10. Revisit Ball Action • Calculate acceleration (Choose 1 of the kinematic equations).

11. Free-Fall Lab • Read lab and create data table to record and organize the information you will collect while performing the lab.