2. 4 Ways to Represent Motion

3. 4 Representations of Motion
Verbal models (language)
Mathematical models (equations)
Graphs
Diagrams(motion maps)

4. 1. Language
scalar – a quantity with only magnitude (a numeric value) but no direction (ex. time)
vector – a quantity with magnitude and direction
time interval (t) – a length of time
SI unit is seconds (s)
Scalar

5. position (x) – the location of an object with respect to an origin
SI unit is meters (m)
vector
displacement (Δx) – change in position
Δ Delta means change in
Δx = xf – xi
Ex: Stew runs 4m to the right of his home then 7m left. What is his displacement from his home?

6. average speed – the total distance traveled in an amount of time (Ex: 3 cm/s)
SI unit is meters
second
Scalar
speed = distance or v = d
time t

7. average velocity (vavg) – total displacement of an object in an amount of time
Speed with a direction (Ex: 3 cm/s south)
SI unit is meters
second
Vector
vavg = displacement or vavg = Δx
time t

8. 2. Mathematical Models(Equations)
speed = distance or v = d
time t
velocity = displacement or v = Δx
time t

9. Steps to Solve a Problem
Draw a diagram of the situation
Identify given variables and unknowns
Convert Units
Write equation and WRITE IT without numbers
Substitute values and solve
Box answer with units (and direction)

10. Example:
A man runs 50 m to the west in 10.0 s, and then 30 m to the south in 6.0s. What is the magnitude of his average speed?
(5 m/s)
Is this the same as his average velocity?
If he continues to run at this average speed, how far will he have travelled in 20 minutes?
(6000m)

11. Turn to Pg 44 in your text book.