1. Chapter 1: Motion
Position and Motion

2. What is position? Position: the location of a place or object.
When you find the position of an object, you are comparing it to where you are or where another object is located.
We might use a reference point to describe position: a point of comparison; or we could use longitude/latitude.

3. Measuring Distance
The standard unit of length is the meter (m), which is 3.3 feet.
Longer distances are measured in kilometers (km), which is 1,000 meters.
Shorter distances are measured in centimeters (cm). There are 100 cm in 1 m.

4. What is motion? Motion: the change of position over time.
Speed: a measure of how quickly or slowly an object moves.
Motion can change frequently because things like speed, acceleration, and direction can change.

5. Relative Motion Motion can appear to change based on perspective.
Imagine a moving bus with students on it.
To someone waiting for the bus to arrive, the driver appears to be moving with the bus, while the bus stop sign stays still.
To the people on the bus, the driver is not moving, while the bus stop sign seems to be changing position.

6. Relative Motion
Usually we consider ourselves the frame of reference to detect motion.
Other times, we use a non-moving background object, such as a tree or a mountain.

7. Chapter 1: Motion
Position and Motion

8. Speed
Speed: measure of how fast something moves, or the distance it moves in a certain amount of time.
the greater the speed, the faster the change in position.
We usually measure speed as a rate.

9. Calculating Speed You need to know both distance and time.
Speed = distance / time or S = d/t
To find speed, simply divide the distance by the time. Using standard units, the answer should be m/s, or meters per second.
One mile per hour (mi/hr or mph) = 0.45 m/s
Kilometers per hour (km/hr) is also commonly used.

10. Using the formula
If you are given distance and time, then you must find speed.
Speed = distance / time
If you are given distance and speed, then you must find time.
Time = distance / speed
If you are given speed and time, then you must find distance.
Distance = speed x time

11. Using the formula - Practice
Shelly rode her bike 80 m in 6 seconds. What was her speed?
13.3 m/s
Tina went 60 m at a speed of 15 m/s. How long did it take her?
4 seconds
John ran 8 m/s for 12 second. How far did he go?
96 m

12. Average Speed
Speed is not constant – we speed up and slow down depending on different situations we are in.
To find the average speed, you add up all of the times that it took to travel and divide it by the total distance.
So, if you ran a 100 m in 10 s, 8 s, 14 s, and 11 s, what is the average speed?
The total time is: 43 s. The total distance is: 400 m.
The average speed is 400/43, or approx. 9.3 m/s.

13. Chapter 1: Motion
Velocity and Graphs

14. Velocity
Velocity: speed in a specific direction (north, east, south, west).
A change in either speed or direction results in a change of velocity.
Velocity is a vector: a quantity that has both size and direction.

15. Velocity vs. Speed
two objects can have the same speed but different velocities if they are traveling in opposite directions.
Average velocity depends on the total distance you are from where you started, not the total distance you have travelled.
Example: you walk 2 miles west down a street at 5 km/hr, then 2 miles east back to your starting spot at 5 km/hr.
Your average speed would be 5 km/hr.
Your average velocity would be 0 km/hr because you ended up where you stared.

16. Distance-Time Graphs Refer to page 21 in your text book.
In a graph, time is on the horizontal axis (x-axis) that goes from left to right. Distance is on the vertical axis (y-axis) that goes up and down.
Motion is shown by lines going up or down. Steep lines up is a fast increase in speed, while steep lines down show a fast decrease in speed.
A flat line shows a period of time with no motion.

17. Chapter 1: Motion
Acceleration

18. Acceleration
Acceleration: a measure of how quickly the velocity is changing.
You may have heard this term before relating to something “speeding up”. However, it relates to any change in velocity.

19. Acceleration
If acceleration is acting in the same direction as the motion already occurring, then the object speeds up.
If acceleration is acting in the opposite direction of the motion, then the car slows down  negative acceleration.
If acceleration is acting at a right angle to the motion, then the direction of the motion will change, but its speed will remain the same.

20. Calculating Acceleration
Change in velocity can be found by comparing the initial velocity and the final velocity.
Time interval over which the velocity changed can be measured.
Acceleration = (final velocity – initial velocity) / time
a = (Vfinal – Vinitial) / t
Measured in m/s2

21. Calculating Acceleration
Anna starts sliding with a velocity of 1 m/s. After 5 seconds, her velocity is 16 m/s. What is Anna’s acceleration?
Initial v = 1 m/s ; final v = 16 m/s ; time = 5 s
a = (16 m/s – 1 m/s) / 5 s
a = 15 m/s / 5 s
a = 3 m/s2

22. Velocity-Time Graphs Refer to page 30 in your textbook.
Time is on the x-axis and velocity is on the y-axis.
A line going up represents positive acceleration.
A flat line = zero acceleration.
A line doing down represents negative acceleration.