1. Physics Lab 2 Graphical Analysis of Motion
Eleanor Roosevelt High School
Chin-Sung Lin

2. Speed & Velocity

3. Speed v = d / t A speed (v) is a scalar quantity
Distance (d) covered per unit of time (t). Speed is a measure of how fast something is moving. It is the rate at which distance is covered
v = d / t
Unit: meters per second (m/s), miles per hour (mi/h), kilometers per hour (km/h)

4. Velocity A velocity (v) is a vector quantity
Velocity is the measurement of the rate and direction of change in the displacement (d) of an object
v = d / t
The speed is the magnitude of velocity
Unit: meters per second (m/s), miles per hour (mi/h), kilometers per hour (km/h)

5. Speed & Velocity Speed has only magnitude
Velocity has magnitude and direction

6. Average Speed Average speed (v): v = d / t
d = total distance covered (m)
t = time interval (s) d
slope = v t

7. Instantaneous Speed
The speed (v) at any instance of an object is called the instantaneous speed
It is equal to the slope of the tangent line at that moment d
slope = v t

8. Average Velocity Average velocity (v): v = d / t
d = total displacement (m)
t = time interval (s) d
slope = v t

9. Instantaneous Velocity
The velocity (v) at any instance of an object is called the instantaneous velocity
It is equal to the slope of the tangent line at that moment d
slope = v t

10. Acceleration

11. Acceleration An acceleration (a) is a vector quantity
acceleration is the rate of change of velocity with time
a = Δv / t
a = acceleration (m/s2)
v = change of velocity (m/s)
t = time interval (s)

12. Acceleration a = Δv / t An acceleration (a) is also a scalar quantity
When linear (straight-line) motion is considered, it is common to use speed and velocity interchangeably and the acceleration may be expressed as the rate at which speed changes
a = Δv / t
a = acceleration (m/s2)
v = change of speed (m/s)
t = time interval (s)

13. Acceleration Acceleration: the slope of the speed-time (v-t) graph v
slope = ax (acceleration) t

14. Constant Acceleration
The acceleration at any instance of an object is constant
In high school physics, we only deal with constant acceleration v a
slope = ax
slope = 0 ax t t

15. Distance-Time Formula
Given initial speed (vi) and time (t), and acceleration (a), the distance-time formula
If the initial speed (vi) is 0, then
d = vit + ½ at2
d = ½ at2

16. Distance-Time Formula
The distance-time formula is a quadratic function!!!
Compare to the standard form of quadratic function:
d = ½ at2
d-t t d
y = ax2

17. Distance, Speed & Acceleration
d-t
v-t
a-t d
slope = increasing at constant rate v a
slope = ax
slope = 0 ax t t t

18. The End