1. DAILY QUESTION January 7, 2009 1. What is the definition of force?

2. Agenda1/7/09 Daily Question Partner Check – Problems Wksht Check-in: Problems Wksht Chapter 10 – Motion New Read Aloud! “Life As We Knew It” Assignments: 1. Study for Quiz on 1/9

3. Force Anything that changes the state of rest or motion of an object

4. Net Force The combination of all of the forces acting on the object. –Balanced forces = net force of zero Do not cause a change in the motion of a moving object –Unbalanced forces = net force is greater than zero Object will move in the direction of greater force

5. Friction A force that opposes motion between two surfaces that are in contact –Static friction: surfaces are stationary –Kinetic friction: surfaces are moving Static friction is usually greater than kinetic friction.

6. Kinetic Friction Different kinds: –Sliding Friction: Object slide past each other –Rolling Friction: Round object rolls over flat surface Rolling friction is usually less than sliding friction. –Fluid Friction: Object moving through a fluid