1. Motion Vocabulary

2. Position
Location of an object with respect to its reference point. (distance and direction)

3. Reference Point
A point to which other points and locations are referred to.
Usually known as the initial position and equal to 0.
Example: John is 20 meters away from his home. (the reference point in this example is John’s home)

4. Scalar Quantity specified by only magnitude (a #)
Ex: mass, time, speed, distance

5. Vector Quantity specified by magnitude (a #) and direction.
Direction can include: north/south/east/west, or - , up or down, right or left, etc.
Ex: displacement, velocity, acceleration

6. Distance Scalar Quantity (mag only) Unit: meter (m)
The total amount of length traveled by an object.
Ex: John runs 20 meters east then 10 meters west.
John’s distance that he ran was 30 meters

7. Displacement Vector quantity (mag & dir) Unit: meter (m)
Straight line distance from the final position to the initial position.
Ex: John runs 20 meters east then 10 meters west.
John’s displacement is 10 meters east from where he initially began.
Δ x = final x – initial x

8. Speed Scalar quantity (mag only) Unit: meter/second (m/s)
Distance covered divided by the amount of time taken to cover that distance:
Ex: John runs 20 meters east in 10 s.
John’s speed is: s = d/t = 20 m/10 s = 2 m/s.

9. Velocity Vector quantity (mag & dir) Unit: meter/second (m/s)
Displacement of object divided by the amount of time.
Ex: John runs 20 m east then 20 m west in 10 seconds.
John’s velocity is: v = Δx/t = 0 m/10 s = 0 m/s

10. Acceleration Vector quantity (mag & dir)
Unit: [meter/second]/second (m/s2)
Change in velocity divided by the amount of time.
Ex: John changes his speed from +20 m/s to +15 m/s in 10 seconds.
John’s velocity is: a = Δv/t = (15-20)/10 = -5 m/s (the negative indicates slowing down in this instance)

11. Motion Equations
Xf - Xi