1. Thursday October 14, 2010 Pick up your science binder from the shelf, place your HW folder, book, and agenda on the front of your desk. 1.What is a force? 2.Name three examples of a PUSHING force. 3.Name three examples of a PULLING force. 4.Name 2 examples of a TWISTING force.

2. GRAVITY & AIR RESISTANCE The physics of falling

3. The Force of Gravity Gravity is the force that pulls all objects down to the earth. Rain falls from the sky down to earth… If you drop a book, it falls to the ground… If you trip, you’ll fall down…

4. Actually in science, gravity is a force of attraction that acts between ALL objects (the earth, you, the desk, a book) The force of gravity is much STRONGER for LARGER objects (more mass). Universal Gravitation

5. Because the Earth is by far, the largest and closest object around, it has the greatest force of attraction... So, no matter where you are on earth, all things fall to the ground due to gravity…

6. Gravity It keeps us from floating away! Gravity is an FORCE which causes the object to accelerate.

7. Objects in Free Fall Do all objects fall at the same rate? Let’s try it!

8. So, which will land first? WHY does the penny land first? Falling objects experience resistance with the air called AIR RESISTANCE that slows them down.

9. Air Resistance The larger the object, the more air resistance. That’s why parachutes work! The upward force of the air acting on the LARGE parachute slows you down as you fall.

10. Review Gravity is the force that pulls all objects down to the earth. Some objects take longer to fall – they are slowed down by FRICTION with the air called AIR RESISTANCE. The larger the surface area, the greater the force of air resistance pushing up. Without air resistance, all objects would fall at the same rate…

11. Galileo Drops the Ball Hammer and Feather Drop on the Moon