1. Physics The Study of Energy Chapter 12 What is Motion?

2. What is your frame of reference? When describing something as moving, you must compare it to something that is assumed to be stationary.

3. The frame of reference can change depending on what is being compared The most common frame of reference is the earth

4. What is motion? What is speed?

5. Motion = change in position in a certain amount of time Speed = the rate at which something moves

6. Formula for calculating speed: speed = distance time

7. Constant speed - speed remains the same over the entire distance Average speed = total distance total time Average speed – speed varies over the entire distance

8. What is Velocity? direction Speed in a given direction Velocities may be given as E 5 m/sec E up 15 Km/hr up circular 10 m/min circular Velocities may be combined

9. If both velocities are going in the same direction, then add velocities If velocities are going in opposite directions, then subtract 10 m/s E5 m/s E = 15 m/s E 10 m/s E 5 m/s W = 5 m/s E

10. When rockets are launched, they are fired in the direction that the earth rotates; thereby gaining an additional thrust of 1800 km/hr (which is the speed that the earth rotates)

11. Acceleration Change in velocity acceleration = final velocity - original velocity time If answer is a negative number, then the change is called deceleration units expressed as velocity/time ex. m/s/s

12. Circular Motion When an object is traveling in a circular motion, it is constantly accelerating because its velocity (speed and/or direction) is constantly changing

13. Momentum the tendency of an object to maintain its motion Depends on the mass of the object and the velocity with which is is traveling momentum = mass X velocity

14. Conservation of Momentum Total momentum of any group of objects remains the same unless outside forces act on the objects