1. Forces Motion and Forces

2. Forces What is a force? A force is a push or pull. What happens when forces combine? Forces combine to produce a net force. Question Answer - The Nature of Force

3. Forces - The Nature of Force Combining Forces The combination of all forces acting on an object is called the net force. “Net” is like the math words “total” or “sum”.

4. Forces Force = a push or pull that one object exerts on another 2 types: balanced vs unbalanced

5. Forces Forces and Motion Forces create a change in velocity (acceleration). Deceleration is negative acceleration.

6. Forces Balanced Forces A force that produces no change in an object’s motion. It is balanced by an equal, opposite force.

7. Forces Unbalanced Forces forces that result in an object ’ s motion being changed +

8. Forces Consider this ball on a table. The forces on it are balanced. Now, consider ball b. If a force is applied to it, it will move. This is a change in its motion due to an unbalanced force Now consider ball c which has the same force applied to it. It will act the same way. However, what if a 2 nd force is applied to it at another point in its path? Its motion will change AGAIN due to the UNBALANCED FORCE on it

9. Forces - Friction and Gravity Gravity Two factors affect the gravitational attraction between objects: mass and distance.

10. Forces - Friction and Gravity Gravity The force of gravity on a person or object at the surface of a planet is known as weight.

11. Forces Free Fall Time is on the horizontal axis, and speed is on the vertical axis. Interpreting Graphs: What variable is on the horizontal axis? The vertical axis? - Friction and Gravity

12. Forces FrictionGravity Comparing and Contrasting Effect on motion Opposes motion Pulls objects toward one another Depends on Types of surfaces involved, how hard the surfaces push together Mass and distance Measured inNewtons - Friction and Gravity

13. Forces Graphic Organizer Friction between an unmoving book and desk Type of Friction Static Occurs WhenExample Sliding Rolling Fluid An object is not moving Two solid surfaces slide over each other Rubber pads on a bicycle’s brakes An object rolls across a surface Ball bearings in skateboard wheels A solid object moves through a fluid Air resistance

14. Forces Calculating Force Practice Problem What is the net force on a 1,000-kg object accelerating at 3 m/s 2 ? 3,000 N (1,000 kg X 3 m/s 2 ) - Newton’s First and Second Laws

15. Forces Calculating Force Practice Problem What net force is needed to accelerate a 25- kg cart at 14 m/s 2 ? 350 N (25 kg X 14 m/s 2 ) - Newton’s First and Second Laws