THE TENNIS BALL MACHINE
About the Author: Name Mrs. Zeenath Reza Khan is a full time instructor with the Department
Faculty of Computer Science and Engineering, University of Wollongong in Dubai. Zeenath has
been teaching since 1996. In 2001 she received the Federal Government Award for Best
Scientific Paper on effects of urbanization on biodiversity of Dubai. She joined UOWD as a part-
time lab assistant in 2001 after graduating with a Bachelor degree in Computer Science. In 2003,
after completing her Masters in International Business with a Distinction, she became a full time
teaching assistant. Since 2005, she is working on her research in Community Informatics, with
one book chapter and seven referred conference papers published. She also presented her paper
and chaired sessions at a conference in Harvard University, Boston, USA. In 2006, Zeenath
restructured Foundation Mathematics and introduced Special Concern Program for Maths,
Jeopardy and Mathalon competitions. In 2008, she received a scholarship from UOWA for her
PhD and became an Instructor; she also received a research grant and was a nominee for
Research Excellence Award 2008. Currently teaching Ethics in Computers
This case was written by Zeenath Reza Khan at University of Wollongong in Dubai Case Writing Workshop under the supervision of
Professor James A. Erskine. It was prepared solely to provide material for class discussion. The author does not intend to illustrate
either effective or ineffective handling of a managerial situation. The author may have disguised certain names and other identifying
information to protect confidentiality.
Copyright 2010, University of Wollongong in Dubai Version: 2010-01-12
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THE TENNIS BALL MACHINE
In August of 2009, Mr. Sahil, a business development manager for Athlete Sports in Dubai,
received a complaint from a customer whose thirteen year old daughter suffered an injury to the
eye due to a malfunctioning tennis ball machine. Fearing this could snowball into a major crisis
for Athlete Sports, Mr. Sahil wondered what actions to take.
Athlete Sports
Athlete Sports, a sports company, was established in 1998 in Dubai by Stefan Van der Merwe,
an avid sports enthusiast. The company started off by offering tennis lessons to both children and
adults, and later on branched out to offer lessons in other sports activities such as basket ball,
football, cricket, and swimming. In the last few years the company began to successfully run
Easter, Winter and Summer camps for children aged between 4 – 14.
Mr. Sahil joined Mr. Merwe in October 1999 as coach at Athlete Sports. With his interest in
sports and his natural ease with students, Mr. Sahil soon became a prodigy for Mr. Merwe. In ten
short years, Mr. Merwe taught Mr. Sahil everything he needed to know about the business and
trained him from bottom all the way up to the position of a Business Development Manager.
With his 10 years of background in this industry, and tennis and cricket coaching certifications,
Mr. Sahil became invaluable to Mr. Merwe as his right-hand man. Their passion for sports and
pleasing people helped the company gain popularity in the form of many contracts with schools
and institutions over a short period of time.
The Tennis Ball Machine
With three major competitors in the market, Athlete Sports decided to position itself carefully by
ensuring its instructors selected for its coaching were always well-trained and certified to teach
the sport they were hired for. This invariably gave Athlete Sports an edge over its competitors,
most of whom usually hired university or school students on part-time basis to full-fill coaching
requirements at a lower cost. In addition to that, the company decided to use two different
categories of balls as directed by the International Tennis Federation (ITF), one for adults and
another for beginners and children which was much lighter and had lower bounce.
Under Mr. Sahil’s management, Athlete Sports focused on cutting costs by hiring equipment
used on a daily basis rather than buying them. One such equipment was the Tennis Ball Machine
that was used by tennis players for practicing their strokes. Renting out these machines reduced
cost of regular maintenance as the manufacturer sent technicians at regular intervals to ensure
smooth running of the machines. Other benefits included free update of the machines in case the
manufacturer had introduced new models and replacement of malfunctioned products for free.
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The Tennis Ball machine allowed for consistency of practicing so that more attention could be
paid to the technicalities of a particular stroke of a player. Coaches preferred to use the tennis
ball machines because they had a holding bin that had the capacity to hold many balls. This
allowed a tennis player to practice for long periods of time without the interruption of picking up
the balls. The computerized ball machines or ball robots allowed users to control the speed,
depth and time between shots to be able to cater to differing student requirements and levels.
Since Mr. Sahil’s employment with Athlete Sports in 1999 and under his influence, Athlete
Sports opted to annually rent out three tennis ball machines from ABC Sports Equipment. In the
process, Mr. Sahil trained the company’s five tennis instructors on how to use the machines
properly and effectively for best practice results for all age groups.
ABC Sports Equipment had been in Dubai since 1990 as a supplier and also a make-shift
manufacturer for some major sports equipment such as the tennis ball machine. In 2008, they
upgraded their tennis ball machine by simply duplicating the existing computerized system of
setting speed, time and depth (digital code system) from the previous version in order to cut
costs. They then released the upgraded version, although not tested for efficiency, and sent them
out to clients such as Athlete Sports by February 2009 before their competitors.
The Malfunction
In March of 2009, a tennis training session conducted by an instructor for Athlete Sports reported
an incident where the speed set in the tennis ball machine did not seem to match the actual speed
at which it released the balls. Due to this misjudgment of speed, Mark Samuel, a 16-year old
beginner injured his wrist as he could not return the serve from the machine. Upon hearing about
the accident, Mr. Sahil met with the instructor and questioned him on the event. The instructor
assured him that he had in fact set the speed correctly and did not know how or why the ball
would have been shot at a faster speed. Mr. Sahil also met with Mark’s parents and apologized
for the incident, hoping for Marks speedy recovery. Mr. Sahil then went on to re-train the tennis
staff to ensure such an event would not occur.
In June of 2009, yet another case was reported. This time, 11-year old Lisa Mary Jay hurt her
hand as the speeding ball smashed into her when she tried to avoid it. Mr. Sahil contacted ABC
immediately and informed them of a malfunction in their machine. ABC denied any such claim
and said they had no complaints from any other clients for the numerous upgraded models they
had sent out. However, upon Mr. Sahil’s insistence, they sent out a technician to have a look at
the machine. The technician tried out the machine and there seemed to be no problems. The
machine shot the ball at the right speed set by the technician. Since the instructor in this case was
different from the first incident, Mr. Sahil decided to be present at each training session to
eliminate any possibility of human error. He set up a radar gun 5m away from the ball machine
and set the speeds and tested to see if the speed on the radar gun and the ball machine were the
same. The balls used were regular adult tennis balls (See Exhibit A).
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In August 2009, during a tennis session that Mr. Sahil himself was coaching along with an
instructor, a third incident took place. The ball machine speed was set at 50km/hr based on 13-
year old Katrina Benedict’s competent tennis level. However, the ball seemed to be shot at a
much higher speed. By the third shot, Mr. Sahil realized the machine was malfunctioning but the
ball had already been shot forward. Katrina was caught off-guard due to the excessive speed of
the ball and it hit her on her left eye, seriously injuring her. Katrina was rushed to the hospital.
She suffered from a swollen eye for three days.
What should Athlete Sports do?
Mr. Sahil now had three cases of malfunction that caused injuries to his clients. He was at a loss.
He knew something had to be done. But what?
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Exhibit A: The Physics
The machine was calibrated for shooting out heavy adult tennis balls which weighed in at
57g, the mini-tennis balls by comparison weighed only 23.5g. Hence the force the machine
used to shoot a ball that weighed 57g was 2.1 N (Newtons=kg m/s2). The machine was
calibrated to exert 2.1N of force on every ball to make it reach the player standing 5 meters
away at a speed of 50km/hr. If the user increased the speed, then the force exerted would be
higher. This part was tested and the machine was given a clean bill of health. However, all
the balls it was tested with and calibrated for were the heavy adult balls weighing 57g.
When the user inserted a ‘Mini-Tennis’ ball in the machine and set the speed to 50km/hr,
the machine which did not have a weight sensor, simply did what it was instructed and
exerted 2.1N of force which was correct if it was a heavier ball.
The effect was that the light ball was thrown at the player at more than double the speed
than the desired. This would invariably decrease the time to react as the ball would be shot
forward much faster than expected.
(Source: Athlete Sports and Independent Investigative Party appointed by the Dubai Courts )