1
IB DP PHYSICS
INTERNAL ASSESSMENT RUBRIC
NAME
DATE
11 July 2020
IA REPORT TITLE An investigation of the launch angle that will maximize the horizontal
range of a projectile launched from a known height.
2
PERSONAL ENGAGEMENT
Teacher comments:
The wider importance of this research was not discussed.
Little creativity, little initiative.
A standard method and standard analysis conducted in a competent way.
The report describes a “commonplace” school investigation with a procedure that has not
been adapted or extended in any way.
3
EXPLORATION
Teacher comments:
RQ not fully focused.
The background information was summarized. Definitions of displacement, velocity and
acceleration were not given, or units, in background information. Units were included in data.
Although air resistance is assumed to be negligible, a known account of its effect on
acceleration and range should have been included in the background information. The effects
of surface area of ball, temperature and air pressure on air resistance where not explained in
the background information but were only mentioned under variables. Measurements of room
temperature and air pressure were not included.
Although h=1.2m is stated to 2 sf. the theoretical value of θ=29.45° is stated to 4 sf.
Calibration of the launch indicator angle was not considered as a source of systematic error.
It could be reasonable to expect more values of the independent variable to be collected within
key ranges to correctly establish a trend.
4
ANALYSIS
Teacher comments:
There were sufficient runs for each trial, however only one measurement of h was given.
Repeated measurements of h should have been included to established whether h was indeed
constant and the size of the random uncertainty in h and its precision established.
The absolute uncertainty in individual range measurements ∆d was not quoted to 1 sf. The
uncertainty was explained but underestimated.
Some uncertainties in dmean where quoted to 2 sf without reason. dmean values should have
then been adjusted to the nearest cm (in most trials).
The uncertainty in an individual u measurement was simply taken from capstone without a
valid reason (any number of decimal places can be chosen in Capstone). The uncertainty in u
mean was incorrectly quoted as 0.01 ms-1, when a column of uncertainties was available.
The uncertainty in θ was decided upon as 0.5°, however the second last column of Table 3
contradicts this (it could be a fractional uncertainty).
Physical conditions such as room temperature and air pressure where not recorded.
Error bars for the independent variable θ were omitted from the graph even though this
variable had the largest % uncertainty. The largest % uncertainty in θ was incorrectly quoted
as 1%. The impact of the uncertainty in θ on the range d was not considered.
The angle for the maximum range was simply chosen as 30°, but a smooth curve through
most of the data points may have revealed an angle less than 30°. Interpretation of the data
was weak.
From the graph, the uncertainty in θ=30° could have been estimated to be ±2° with
justification.
Curves of best fit should be drawn through the error bars to produce a minimum angle, a
maximum angle and a best fit angle so that the final angle with its uncertainty can be obtained.
5
EVALUATION
Teacher comments:
A more thorough interpretation of the trend of the graph would suggest a smaller angle than
30° would produce a maximum range. A single data point cannot be used as strong evidence.
Min, max and best fit curves to fit the experimental data should have been attempted.
The deviations from the theoretical curve (and the reasons for this deviation) were not fully
explained when concluding.
In evaluation, friction was mentioned, and its influence weakly explained (its effect on the
vertical acceleration was not attempted) but it did not feature in the conclusion.
Precise measurements of u were considered to be a weakness, which is confusing.
There was a calculated theoretical value of θ to compare with, yet in the evaluation, the report
says otherwise.
“improving precision reduces systematic errors” is incorrect.
The term “systematic error” is used often without example or discussion.
Conclusion is weak. Simply outlined, superficially compared to an accepted value, not
described in detail. Because the data was not analysed effectively, the conclusion is not
supported by the data.
Limitations, sources of error are simply described, a clear discussion of the impact showing a
better understanding is required.
Explanations of exactly how the improvements should result in improved measurements is not
discussed in detail.
Improving precision does not reduce systematic error.
Performed in a vacuum is not realistic.
High achievement in evaluation will arise in reports where the candidate has a strong
understanding of the methodological issues involved in establishing the conclusion.
A candidate who only addresses practical or procedural issues, by simply giving an account
of how their results could be improved by carrying out their stated procedure better, only fulfils
the lower level of this aspect.
The potential implication of modifications and how they might bring the experimental results
closer to what is expected should be discussed.
The extension suggested should follow on from the research in a meaningful way and show
how it will enhance understanding of the topic or RQ. It should be clear why knowing this may
be important.
6
COMMUNICATION
Teacher comments:
A clear presentation, well-structured and relevant.
Labelled photos, well-structured data tables and graph all helped understanding.
Some errors in the use of terminology:
“Acceleration acts on the ball”.
The use of the term “precision” was not always used correctly.
Remove the appendix and simply state the results of the derivation in the background
information. Apparently, according to Ms Brown, it won’t be marked.