|
Like distance and
time, speed and time can also be placed visually on a graph as well. A speed -time
graph that has a slope greater than zero shows an object accelerating, graphs
that shows a straight means a constant speed is being kept, and a negative slope
means the car is decelerating. The steeper the slope, the faster it is either
accelerating or decelerating.
This page will
pose a new way of showing acceleration using a graph. Acceleration is the change
in speed over time. Usually in a speed-time graph the speed is represented as
the change in y ( y) or the
y-axis. The time is represented as the change in x ( x)
or the x-axis. The equation of the slope is still defined as the change in y divided
by the change in x Slope
= ( y/ x) To calculate
the Acceleration from a speed time graph you must calculate the slope the same
way you would fine the average speed from a distance-time graph. (click
here) What
does the area under the line mean? The
area under the slope represents the total distance. Using mathematical formulas,
you can find the area under the line. Normally shape in which the area can be
measured from willl only form a triangle or a square, or both. This
theorem still proves the area under a speed-time graph equals the distance travelled
during that time interval.
| Sample 2 
Using
the above graph you can calculate the area. (in meters) i) Divide the slopes
in to geometric shapes if necessary ii) Decide what formulas to use
| Triangle | |
Area = (Base x Height) / 2 | | Sqaure | | Area
= Base x Height | iii) Calculate the areas
| Triangle | |
Area = (Base x Height) / 2 | (4 x 5) / 2 = 10m |
| Sqaure | | Area
= Base x Height | (9-4) x 5 = 25m | iiii)
Add areas if necessary 10m + 25m =35m | Continue
to next lesson: ::Instantaneous speed::
|