Kinematics Terminology
Kinematics
:
Study of motion of objects
Scalar
:
a number (measurement) that has units
eg: temperature 20 C, height 180cm, speed 40 km/h,
time 30 min.
Vector
:
a number (measurement) that has units and a direction
eg: veloc
ity 100 km/h [E], position 25m[W]
Acceleration 5m/s
2
[S]
Distance, Position, Displacement
Distance
is the length of a path taken by an object as it moves
from one location to another. Distance is a scalar quantity
since direction is irrelevant.
Pos
ition
is the location of an object with reference to a specific
location. Position is a vector quantity since a direction
must be stated, usually in square brackets.
The SI Unit of measurement for length is the metre.
d=distance
Scalar distance walked t
o school 2 km
d=position
Vector (direction) 1 km[E] then 1 km[S]
* arrow on top of measurement variable indicates vector
Displacement
is the
net difference in position
from the start
location of the object to the end location. Displacement is
a vecto
r quantity since it comes from difference in position,
which has a direction.
d= 1.4 km[SE]
Drawing Vectors
Must show your reference coordinates and indicate
a scale 1 cm=1 m or 1 cm=5 km etc.
Always use a ruler to draw the appropr
iate length of vector and
a protractor to indicate the exact direction.
Eg: d=10 km [E]
(line is 2 cm long using scale 1 cm=5 km)
Negative Vectors
8 km [W] =

8 km [E]

8

7

6

5

4

3

2

1 0 1 2 3 4 5 6 7 8
We can multiply a vector by scalar; the magnitude changes but
the direction does not.
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