1. Motion, Speed, Velocity, and Acceleration
Ms. Whitworth
6th grade science

2. Motion
Motion- when an object changes its position relative to a reference point.
In order to know something has moved, you need to know the point from where it started.

3. Distance Distance – how far an object has moved.
The SI unit of length is the meter (m).
Longer distances are measured in kilometers (km).
Shorter distances are measured in centimeters (cm).

4. Time Time - an instance or single occasion for some event.
The SI unit of time is the second (s).
Other units for time are the minute, hour, days, years, etc…

5. Speed
Speed – the distance an object travels divided by how long it took (time).
37.5 km/hr

6. Instantaneous Speed The speed at a particular point in time.
Example-speedometer in car.

7. Constant Speed
Means that the speed of the object under consideration is NOT changing.
Example-cruise control

8. Average Speed
TOTAL distance traveled divided by the total time it took.
EXAMPLE: Trip from El Paso to Las Cruces.

9. Velocity
Velocity– the distance an object travels divided by how long it took (time) in a certain direction.
37.5 Km/hr West

10. Velocity
The velocity of an object can change even if the speed remains constant.
Ex. going around a curve in cruise control

11. Calculating Speed/Velocity
V=d/t (distance divided by time)
V = Velocity (m/s)
d= distance (m)
t = time (s)

12. Example 1
A bicycle rider travels 60.0 km in 3.5 hours. What is the cyclist’s average speed?

13. Example 2
What is the average speed of the car that traveled a total of miles in 5.5 hours?

14. Graphing Motion
A distance-time graph makes it possible to display the motion of an object over a period of time.
The slope of the line represents the speed. The steeper the slope, the faster the speed.
The horizontal line means that the velocity is zero.
Distance is always plotted on the y- axis and time is always on the x-axis.

15. Distance-Time Graph

16. Distance-Time Graph

17. Distance-Time Graph

18. Distance-Time Graph

19. Distance-Time Graph

20. Distance-Time Graph Questions
What is the speed at B-C? ____________
How far did the car drive before it stopped the first time? _________
How far did the car drive the whole trip? ___________
How long did the whole trip take? __________
What is the car’s average speed? ___________

21. Velocity-Time Graph

22. Acceleration
Acceleration is the rate of change in velocity. When the velocity of an object changes, the object accelerates.
Acceleration occurs when an object changes its speed, direction, or both.
When an object increases it velocity it is called acceleration, when an object decreases its velocity it is called deceleration.

23. Acceleration Formula a = Vf –Vi ------------- t
Vf = final velocity (m/s)
Vi = initial velocity (m/s)
a = acceleration (m/s2)
t = time (s)

24. Example 1
A skateboarder is moving in a straight line at a speed of 3m/s and comes to a stop in 2s. What is the skateboarder’s acceleration?

25. Example 2
A flying doughnut increases its speed from 30m/s to 145 m/s in 11.6 s. What is its acceleration?