1. Section 1 p
Ch. 18 Motion and Momentum

2. What is motion? A change in position
Motion occurs when something changes position relative to a point of reference.

3. Point of Reference
The point that is used to determine if an object changes position
Example-If the starting line is your point of reference in a 100m race, then your position has changed by 100m relative the starting line and motion has occurred

4. Distance
Distance is the length of the route you travel.

5. Displacement
The distance between the starting point and the ending point and the direction you travel.

6. Speed Speed is the distance an object traveled in a unit of time.
Speed (meters /second)= distance (in meters)
time (in seconds)

7. Average Speed
Divide the total distance traveled by the total time.

8. Instantaneous Speed
The speed of an object at one instant in time.

9. Constant Speed
A speed that stays the same the entire distanced traveled.

10. Graphing Motion Use a distance-time graph
Time is always plotted on the x-axis
Distance is always plotted on the y-axis
The steeper the line the greater the speed
A horizontal line means there is not change in position, which means the speed is zero.

11. Velocity
The velocity of an object is the speed of the object and the direction of its motion.
Velocity can change
if the object’s speed increases or decreases
Direction of motion changes
Or they both change