1.2Speed and Velocity
Speed
•Speed is a scalar quantity that measures distanceover time. There are 3 types of speed:
•Instantaneous Speed: The speed of an object at aparticular moment in time
–Example: Speed measured by a radar gun
•Constant Speed: Occurs when the instantanousspeed remains constant over a period of time
–Example: Using cruise control
Speed
•Average Speed: The total distance travelleddivided by the total time elapsed for a trip
–Equation:
Where: Δd = distance travelled
Δt = elapsed time
Examples
Sally rides her bike to school. It is a distance of8.0 km. If it takes her 15 minutes, calculate heraverage speed (in km/h).
Fred can roller blade at a speed of 11.5 km/h. Ifit is 4.5 km to his friend’s house, how long will ittake him to get there in minutes?
•Velocity is a vector quantity that measures thechange in position over time. There are threetypes of velocity:
•Constant velocity: occurs when traveling at aconstant speed in one direction.
Velocity
Velocity
•Average velocity: The resultant displacementdivided by the total time elapsed
Where Δd = resultant displacement
Δt = time
Examples
It takes John 30 minutes to drive home fromwork. If his resultant displacement is 26 km [W]what is his average velocity (m/s)?
The average velocity of a Canadian goose is 2.5m/s [S]. How long will it take for the goose totravel 5 km [S]?
Examples
Anna ran 4 km [E] then 3km [S]. If the entire runtook her 45 minutes.
a.What was her average speed (km/h)?
b.What was her average velocity (km/h)?
c.Why are the two values different?
Homework
Questions
p. 15 #1-3
p. 18 #1-2
p. 20 #6-8
