• A scalar quantity is one that only indicates
“ how much ” ( the magnitude) of the quantity.
• A vector quantity indicates the “ how much ” ( the magnitude) AND the direction of the quantity.
A vector quantity is written with an arrow
( ) above the quantity.

Vector directions;
When working with vectors
(especially adding vectors), we need to know how to represent the direction. Our textbook looks at 2 different methods (see pages 139 and 140).
1. X – axis method
[up] and [right] are positive
[down] and [left] are negative
Other directions are given in degrees from the right axis (x-axis) in a counter clockwise direction.
2. Navigator method (compass)
[N] and [E] are positive
[S] and [W] are negative
Other directions are given in degrees from [N] in a clockwise direction

• Distance is a measurement of the change in distance of an object moving from a starting reference point. Distance is a scalar quantity.
Example: ∆d = 5 m
• Displacement is a measurement of the change in distance and the direction or the change in position of an object from a reference point.
Example: ∆d = 5 m [right]

• Speed describes the rate of motion of an object. Speed is a scalar quantity.
Example: v = 100 km/hr
• Velocity describes both the rate of motion and the direction of an object, so velocity is a vector quantity.
Example: v = 100 km/hr [E]

• Velocity is a vector quantity, so you must state its magnitude and direction.
Average velocity = displacement time v = ∆d
∆t v = d final t final
- d initial
- t initial
The units for velocity are the same as speed; metres/second (m/s) but you ALSO include a direction in square brackets behind the units given. Example; 10m/s [west]

Example Problem B1.6 page 141
Practice Problems #8, 9, 10 page 141

Using Graphs to Analyze Average Velocity
NOTES provided.
– Position-time graph
 Is similar to distance-time graph (determining average speed by slope of the line) except that velocity and position (displacement) are vector quantities and must be stated in terms of magnitude and direction
 Average velocity = slope
– Velocity-time graph
 Is similar to speed-time graph (determining distance by calculating area under the line) except that velocity is a vector quantity and must be stated in terms of magnitude and direction
 Area = ∆v x t

Check and Reflect page 145 #1, 2, 3, 4, 5, 6