Motion Prac 3
Inclined Plane Velocity-Time Data
Analysis & Report
Print out the prac pages from the
wiki and then answer the questions
using the following slides as a guide.
Motion Prac 3
Manual Graphical Analysis
1. Draw a velocity-time
graph of these results.
Draw a line of best fit and
lines to represent
plausible maximum and
minimum gradient lines.
• This is RJ’s interpretation of the line of
best fit and maximum and minimum
gradients. Your interpretation will
probably vary slightly.
• When you draw your graph you should
really try to do it on graph paper.
• You should put your gradient triangles
and calculations on the graph.
(Naughty RJ did not put the gradient
triangles on the graph.)
Motion Prac 3
Manual Graphical Analysis
2. How can the acceleration of the cart be worked out from its
velocity-time graph?
The acceleration can be found from the gradient of the
velocity-time graph
Motion Prac 3
Manual Graphical Analysis
3. Complete the table below and work out the acceleration of
the cart with an appropriate error?
These results are from RJs
graph. Put in your own results
From the graph in Appendix 1
Gradient
Diff. from line of
best fit
Line of best fit
1.5455 ms-2
0
Minimum gradient
1.4545 ms-2
– 0.091
Maximum gradient
1.5709 ms-2
0. 0254
So Acceleration = 1.5455 ms-2  0.091 ms-2
= 1.55 ms-2  0.09 ms-2
We always round off
errors to 1 sig fig and
then round off the
place value of the error
Motion Prac 3
Manual Graphical Analysis
4. Use Excel to create a velocity-time graph from the data in
table 1 and draw a line of best fit.
• Download the file
Motion Prac 3a3
Sup Material - Inlc
pln 1 v-t Excel Data
For Practice v6
from the wikispace.
• Create this graph
using the instructions
on the prac sheet
• Add the trendline and
equation using the
instructions on the
prac sheet
Motion Prac 3
Manual Graphical Analysis
5. Complete the following details from your Excel graph.
v = 15052
…....…. t + 0.1652
…....….
Because the acceleration is the gradient of a v-t graph
acceleration = 1.5052 ms-2 with an r2 correlation of 0.9822
Motion Prac 3
Manual Graphical Analysis
6. Calculate of the % Deviation of Manual Graph Results compared
with the Excel Analysis.
From the Excel graph in Appendix 1
Table 1.2 Manually drawn graph and excel acceleration results
Acceleration
from manually
drawn graph
1.5455
ms-2
Acceleration from % deviation of manual results from excel
excel analysis
analysis
1.5052
Enter the acceleration you
found from your graph
ms-2
0.0403
1.5052
× 100 = 2.677%
 3%
Motion Prac 3
Manual Graphical Analysis
7. How do the results from your graph compare with those from the
calculator and what is your final estimation for the acceleration of the
cart down the ramp? (mention each result, the % deviation in the first
sentence, a comment stating how the two results correlate and a
conclusion regarding the final result Results within 5% are said to strongly
support each other.)
The acceleration from the manual method of 1.5455 ms-2 is less than 3%
above the 1.5052 ms-2 determined from the Excel analysis which means
that they strongly support each other.
The excel graph seems to match the points a little better than the
manual line of best fit so it is seen as the best approximation to
acceleration. Taking into account the maximum and minimum
gradients from the manual graph the final result of the experiment is
estimated as 1.50 ms-2  0.07 ms-2
Motion Prac 3
Manual Graphical Analysis
8. When might a hand drawn line of best fit give a more accurate result than
an excel analysis
A hand drawn line of best fit may give you more accurate
results if there were a lot of outliers that might distort the
averaging process used by excel.