Appendix I
Warning!
Maybe you have noticed that position-time graphs and distance-time graphs are not
the same. Here is a brief explanation about the subtle difference between these two
quantities graphs:
In a position-time graph, position is plotted on the y-axis and the time is on the x-axis. In a
distance-time graph, direction of motion is in the y-axis.
Distance
Position
east
Time (s)
Time (s)
Although these forms of graphs can produce similar results, this is not always the case. Lets
assume you went for a walk to the nearby
Distance-time walking to a store
Distance
store (10 km north) and back to your original
reference point, this would mean your total
20 km
travelled distance is 20 km (10km to the store,
and 10km back). This distance-time graph
would look like the graph on the right:
But if this were a positional-time graph, then it
would look like the following:
Time (s)
Position
North
10 km
Time (s)
Appendix II: KINEMATICS WORD MAT. (front)
DISTANCE – TIME GRAPHS
VELOCITY – TIME GRAPHS
Fast steady
speed
gradual
Getting
acceleration
faster
steady
steady
speed
Stopped
acceleration
speed
VELOCITY
Stationary
DISTANCE
Steady
Returning to
Start
steady
deceleration
TIME
TIME
Very important notes
a.
Gradient= speed
b.
Flat sections are where it’s stopped.
c.
The steeper the graph, the faster the motion
d.
Downhill sections mean it’s going back toward it’s starting point
e.
Curves represent acceleration or deceleration.
f. A steepening curve means it’s speeding up (increasing gradient)
g.
Levelling off curve means it’s slowing down (decreasing gradient)
Calculating speed from distance-Time graph
speed
gradient
vertical
horizontal
Don’t forget that you have to use the
scale of the axes to work out the
gradient
Very important notes
a.
b.
c.
d.
e.
f.
Gradient= acceleration
Flat sections represent steady speed.
The steeper the graph, the greater the acceleration or deceleration
Uphill sections (/) are acceleration.
Down hill sections (\) are deceleration.
The area under any section of the graph (or all of it) is equal to the distance
travelled in that time interval.
g. A curve means changing acceleration.
Calculating acceleration, speed and distance form V-t graph
accelerati on
gradient
area under the graph-
vertical
horizontal
The speed: by reading the
value off the velocity axis.
This distance by calculating
Appendix II: KINEMATICS WORD MAT (back)
LINEAR MOTION EQUATIONS
UNIFORM
s sO V .t
UNIFORMLY ACCELERATED
s sO
V0 .t
V
a.t
V0
FREE FALL
y yO
1 a.t 2
2
V
1 g.t 2
2
g.t
Some Maths:
Components of a vector
Displacement vs distance
Velocity vs speed
Speed
Velocity is a vector quantity.
Speed is the magnitude of
this vector