1. May the Force be With you! The following information will force you to learn more about FORCE.

2. A force is defined as – A Push or a Pull

3. Unbalanced Forces 1.An unbalanced force acting on an object will change an object’s motion. 2. Net force-sum of all forces acting on an object 3. Example- If an unequal force is applied to an object, the object will accelerate in the direction of the greater force. + = + =

4. VECTORS Vectors are arrows that show the direction and strength of forces. The resultant shows the outcome of those forces. If an unequal force is applied to an object, the object will accelerate in the direction of the greater force. + =

5. Balanced Forces 1. A balanced force acting on an object will not change the object’s motion. 2. Net force is equal to zero 3. Example- If equal forces exerted in opposite direction are applied on an object, it will not move + = 0

6. VECTORS If equal forces exerted in opposite direction are applied on an object, it will not move. The vectors will cancel out each other and the resultant will be zero. + = 0

7. Balanced and Unbalanced forces Summarizing Questions for Balanced and Unbalanced Forces: have the answers under your notes 1. What is a balanced force? 2. What is an unbalanced force? 3. Draw a picture that shows an example of a balanced force (examples: a bird 's nest in a tree, a hat on a person's head, or a light hanging from a ceiling). Show the forces acting on the object. In a separate picture show what would happen to the object if the forces became unbalanced. 4. A driver and a passenger get out of their car that has run out of gas on a city street. They cannot agree on which gas station is closer, so they begin pushing with equal force on opposite ends of the car. (a) Make a sketch of this car-pushing situation using arrows to represent the forces on the car. (b) Use your sketch to explain whether the forces on the car are balanced or unbalanced. (c) Re-draw the sketch with force arrows illustrating a more effective way for the driver and passenger to get the car to the gas station. (d) Does this new sketch illustrate balanced or unbalanced forces? Explain.

8. Friction 1.Friction is the force that one object exerts on another when the two rub against each other. 2. Friction is a force that acts in the opposite direction of the motion of the object.

9. Friction 3. The strength of the force of friction depends on two factors: A. type of surface B. how hard the surfaces push together 4. Examples of how friction is useful: A. helps us to walk without slipping B. helps us to light matches 5. Different types of friction include: A. sliding friction B. rolling friction C. fluid friction

10. Gravity 1.Gravity is the force that pulls objects toward Earth. 2. Gravity exists everywhere in the universe, two factors that affect gravity are: A. size of the objects B. distance between the objects

11. Air Resistance 3. Air Resistance- Objects moving through air experience fluid friction. Air resistance increases because of: A. size of the object B. speed of the object NOTE: In Space and in a vacuum there is no air, so there is no air resistance.

12. Free fall 4. Free fall- is the rate at which all objects accelerate as they fall to Earth ALL objects regardless of mass fall to Earth at a rate of 9.8m/s/s If a Squirrel drops an acorn from a branch it falls at a rate of 9.8m/s/s. How fast is the acorn falling after 3seconds? 9.8m/s/s X 3 sec=29.4m/s YouTube - MIT Physics Demo -- Strobe of a Falling Ball Terminal Velocity If a man with a parachute jumps from a plane he will fall at a rate of 9.8m/s/s. His speed eventually stops increasing when the air resistance becomes equal to the force of gravity. What happens if you drop a penny off of the Empire State Building? If the penny falls for 6 seconds when it reaches terminal velocity what is its speed? 9.8m/s/s X 6.6 sec= 64.7m/s YouTube - Mythbusters - Death by a falling penny?

13. Projectile An object that is thrown is called a projectile. An object that is thrown and dropped at the same time will hit the ground at the same time. YouTube - MythBusters Bullet Fired DroppedYouTube - MythBusters Bullet Fired Dropped