ENF 1104. Kinematics Activity
Introduction
(V. Rouillard – 2010)
(Photographs courtesy RIT)
ENF 1104. Kinematics Activity – Introduction (V. Rouillard – 2010)
Preamble
Following yet another convincing win by Roger Federer at the Australian Open, his
opponent, Irma Badlouzhur, from the Peoples’ Republic of Naugudatsphort has
decided to lodge a formal protest. Badlouzhur alleges that, apart from being far
better looking, Federer used a “magic” racquet that has a coefficient of restitution
(CoR) greater than unity and therefore illegal.
Federer: Handsome
Badlouzhur: Very ugly
ENF 1104. Kinematics Activity – Introduction (V. Rouillard – 2010)
Preamble (cont’d)
The Australian Tennis Federation (ATF), which is responsible for organising the
tournament, decided to deal with the protest by commissioning tests to
determine the coefficient of restitution of Federer’s racquet. This was undertaken
by an independent laboratory, Rebound Labs Inc., based in the small European
state of Lichtenstein. Unfortunately (or perhaps suspiciously), before the results
were released, the main building of Rebound Labs Inc. caught fire destroying the
test samples (Federer’s racquets) as well as most of the test data. Needless to say
allegations of ‘foul play’ and ‘suspicious circumstances’ were reported in the
popular press and other news media.
ENF 1104. Kinematics Activity – Introduction (V. Rouillard – 2010)
Preamble (cont’d)
Fortuitously, files containing high-speed video footage of two of the tests were
salvaged from the remains of the building and handed-in to the ATF by the
Lichtenstein authorities. The ATF protest committee, being past tennis players and
having little understanding of kinematics, have approached you for assistance.
Video preview
Instructions on how to access the image sequences are in the hand-out)
ENF 1104. Kinematics Activity – Introduction (V. Rouillard – 2010)
The challenge
The ATF needs to know whether the video footage can be used to determine the
type of test carried-out on Federer’s racquet and whether accurate estimates of
the coefficient of restitution can be made from the footage. Specifically, the
following questions / issues need to be addressed and included in your report:
ENF 1104. Kinematics Activity – Introduction (V. Rouillard – 2010)
The challenge (cont’d)
(a) Were the tests carried-out in free-fall or was the ball launched from a
machine?
(b) If the tests were carried in free-fall, was the gravity field constant? Your
response must be accompanied by a short discussion on the effects of
altitude on gravitational acceleration.
(c) If the gravitational field during the tests was constant what was it?
(d) What are the variations in displacement, velocity and acceleration of the
tennis ball with respect to time? This must be accompanied by a discussion
on how these relate to theory.
(e) What is the coefficient of restitution between the ball and the racquet? This
must be accompanied by a thorough discussion on the uncertainty of your
estimates. Discuss your results in the context of rules for tennis. You also
need to advise the ATF on better ways of determining the CoR of tennis
request.
ENF 1104. Kinematics Activity – Introduction (V. Rouillard – 2010)
Deliverables and assessment
Team Preparatory task (compulsory)
Start during session 1 , complete in own time (team work) , hand0in to facilitator
during session 2.
Technical report (6 marks)
Team technical (written) report to be completed and submitted to your designated
facilitator before the start of the first session of week 8. After it is assessed, you
may collect you report from you facilitator along with comments and feedback on
your effort.
Reflective journal (2 marks)
The submission deadline for the reflective journal is the same as that of the
report.
Quiz (4 marks)
Duration: 50 mins. To be undertaken during the last hour of the last session. The
quiz is a closed-book session and is to be attempted by each student individually
(no team work allowed) – examination conditions will apply.
ENF 1104. Kinematics Activity – Introduction (V. Rouillard – 2010)
Schedule of activities
Lecture
Week 7
Week 6
Session 1
Own time
Session 2
Own time
Lecture
Session 1
Own time
Session 2
Introductory lecture on kinematics. Important information regarding the video
footage will also be given during this session.
Familiarisation session. Start to work on Team Preparatory Task and brainstorm your team’s approach to tackling the challenge.
Complete team preparatory task.
Review team preparatory task and further brain-storm your team’s approach to
tackling the challenge.
Work as a team to analyse both files containing high-speed video footage.
Attend lecture on applications of kinematics.
Present your results and preliminary analysis, undertake further analysis, start
working on report.
Prepare your report
Present draft of report to facilitator and obtain feedback. Quiz.