1. 1D Motion
Time and How Far

2. Time
You can talk about an instant in time or an interval of time

3. Time “What time does class end?” An instant of time.
ti = initial instant of time tf = final instant of time

4. Time ∆t = tf – ti (final time – initial time)
“How long does class last?”
time interval
∆t = tf – ti (final time – initial time)
Note: Greek letter delta (∆) = change

5. Time in a motion graph
Time is ALWAYS the independent variable on the x-axis on a motion graph

6. How far? 3 different answers
distance – the length of the trip you traveled
position – where you are from a reference point
displacement – the overall change in position– path does not matter
change in position (xf – xi or ∆x)

7. How far? 3 different answers
Start at position -2 and move right 5 units and then left 4 units
1) distance – the length of the trip you traveled

8. How far? 3 different answers
2) position – where you are from a reference point (distance & direction)
The position axis along which an object moves:

9. How far? 3 different answers
3) displacement – from start to stop of a trip (distance and direction)
The position axis along which an object moves:

10. SCALAR
Magnitude
Time
VECTOR
Magnitude & direction

11. SCALAR
Magnitude
Time
Distance
VECTOR
Magnitude & direction
Position
Displacement

12. Walk it Mailbox = reference point position, distance, displacement
Start at door and walk straight out – position, distance and displacement all the same. Pick a new start point on that straight line and walk in that straight line – distance and displacement the same, position different. Go on a right angle trip and finish where you started…long distance, different position, displacement 0. One where none are the same and displacement not zero, Pythagorean triangle trip.