View Full Version : Physics of Sport Conference - UK

Stephen Haake
01-24-1995, 10:14 PM
25th January 1=
Dear Colleague,
Please find below the final programme for the one day
meeting "The Physics of Sport". If you are interested in attending then
you can contact the Institute of Physics meetings department directly using
email on


Alternativley, the address to write to for further details is,
Ms Lucy Bell,
The Institute of Physics,
47, Belgrave Square,
London, SW1X 8QX,

The cost of attendance is shown below,

Half day (=A3) Full Day (=A3)
Members of IOP 22.50 45.00
Other Members 27.50 55.00
Non members 42.50 85.00
Students 5.00 5.00

************************************************** **************************=
The Physics of Sport
The Institute of Physics Congress
Telford International Centre, Telford, Shropshire, England
30th March 1995
************************************************** **************************=


10.00 Coffee and Registration

10.20 The engineering of a sports bike
Dr Richard Hill
Lotus Engineering, Hethel, Norwich, Norfolk, NR14 8EZ.

ABSTRACT: Not yet received. The intended presentation will cover the
development of the revolutionary Sports Bike used by Chris Boardman in his
Gold Medal win at the last Olympics.

11.00 The mechanics of golf equipment
Dr Alastair Cochran
Technical Consultant, The Royal and Ancient Golf Club of Saint Andre=
St Andrews, Fife, KY16 9JD, Scotland.

ABSTRACT: There are three phases of a golf shot - the swing of the club,
the club/ball impact and the flight of the ball. Some aspects of the
club/ball impact will be considered and the factors in clubhead design will
be discussed. The amount of backspin imparted to the ball by the club, the
ball's dimple design and lift and drag characteristics are all important
factors in the balls's trajectory which will be covered.
The presentation will discuss Research Development in modern club
ball and design and the in this context the question will be asked, "Where
are we going?"

11.40 Coffee

12.00 Modelling for an improved cricket bat
Dr C. Grant and Dr A.D. Baird
Department of Mechanical, Materials and Manufacturing Engineering,
Stephenson Building, University of Newcastle, Newcastle upon Tyne
NE1 7RU.

ABSTRACT: Improvements in design and the use of modern synthetic materials
in golf clubs, hockey sticks and tennis rackets now allow the ball to be
hit much harder in those sports. Comparable innovations in cricket bats
are rare. During the present century changes have been largely restricted
to variations in the weight of the bat and its distribution.
In an idealised normal elastic impact, the ball is propelled at twice the
speed of the bat at the point of impact plus the original speed of the
ball. This very simple rule is modified substantially by inelastic effects
and by bat inertia. The latter shifts the optimum point of impact up the
blade by an amount that increases with faster bowling. However, a high bat
speed at the point of impact remains a crucial factor.
Under conditions of oblique impact, when the face of the bat is not
normal to the ball's trajectory, large tangential friction forces can occur
between bat and ball. These forces produce angular momentum in the ball,
in addition to the linear momentum produced by the normal forces. High
spin rates introduce large aerodynamic "lift" forces on the ball due to the
Magnus effect. These forces act normal to both the trajectory and the spin
axis, and cause the ball to swerve in flight. Although these effects are
readily observed, they are not important in cricket per se. Furthermore,
the essential characteristics of normal impact are preserved since normal
and tangential impact are virtually uncoupled.
A recent study has shown that energy absorbed in flexural
vibrations can be a significant factor that affects the performance of a
bat, whilst rigid body analysis provides an idealised performance model.
Department of Mechanical, Materials and Manufacturing Engineering,
Stephenson Building, University of Newcastle, Newcastle upon Tyne, NE1 7RU.

12.20 A theoretical model for the prediction of forces developed during a
rock climbing leader fall
Dr M.J. Pavier
Department of Mechanical Engineering, The University of Bristol,
Bristol, BS8 1TR.

ABSTRACT: The modern rock climber puts considerable trust in his climbing
rope: falls while climbing are commonplace, particularly for experienced
climbers attempting difficult routes, and the consequences of rope failure
are usually serious. Climbing ropes are designed to withstand numerous
falls but have a finite life, therefore old rope should be retired from
use. Currently no quantitative measure exists of the effect of a fall on
the remaining life of a rope so climbers must rely on rule of thumb
guidelines for retiring old ropes. Here a theoretical model is described
that predicts the severity of a fall and allows in principle an estimate of
the remaining life of the rope.
Climbers invariably climb as a pair known as a leader and second.
The second attaches himself to the rock face, a process known as belaying,
then ties himself to one end of the rope. The leader ties himself to the
other end of the rope then climbs above the second to the top of the rock
face. As the leader climbs the second pays the rope out through a belay
device designed to allow the second to hold the rope tight in the event of
the leader falling. Once the leader has belayed himself at the top of the
rock face the second removes his belay and climbs to rejoin the leader, the
leader taking in the rope as he does so. The critical part of the
procedure is as the leader climbs above the second. To make this part
safer the leader runs the rope through karabiners (metal clips) attached to
the rock. Should the leader fall the distance fallen is only of the order
of twice the distance to the last karabiner.
The theoretical model uses expressions relating increments of
tension and strain in for a rope segment between two adjacent karabiners,
allowing large strains and non-linear behaviour of the rope to be accounted
for. These expressions are combined with relationships governing slip of
the rope past karabiners and through the belay device enabling an
incremental solution for the tension in each rope segment during a fall. A
computer is necessary to carry out the solution as several matrix
multiplications and inversions are required for each increment. Results of
the model show a good agreement with experimental measurements of forces
developed during a fall.

12.40 The role of the club head response in golf club design
Dr Steve Mather
Department of Mechanical Engineering, The University of Nottingham,
University Park, Nottingham, NG7 2RD.

ABSTRACT: For many years, manufacturers of golf equipment have promoted
the properties of their implements. Claims are made for the distance
achieved in ball flight, the narrow dispersion of that flight and the
differential ability to generate back spin on the ball. It is clear that
some clubs do seem to outperform others and yet this performance is not
consistently achieved within a set of golf clubs let alone across a
manufacturers range or by different manufacturers.
In an attempt to explain these anomalies, this paper examines the
role of the dynamic response of the club head to the large impulsive force
applied to it by the ball at impact. This force can be over lOkN for a
duration of 450 ms. Correlations are shown which show how the modal
response at the low orders governs the deviation of the head leading to
changes in the angle of the head, and side spin and backspin. Data is
given for a number of different heads characteristic of the blade and
cavity back designs current on the market.
Manufacturers' claims are usually made from results of tests
conducted on professional golfers or on robotic machines. In reality the
results with amateur golfers differ greatly and therefore the paper also
discusses the implications of the dynamic response of the head for this
category of golfer.

13.00 Lunch

14.00 ************Plenary Session***************
The aerodynamics of sports balls
Dr Rabindra D. Mehta
Mail Stop 260/1, NASA Ames Research Center, Moffett Field, Californi=
94035-1000, USA.

ABSTRACT: Aerodynamics plays a prominent role in the flight of a cricket
ball released by a bowler. The main interest is in the fact that the ball
can be made to follow a non-linear flight path which is not always under
the control of the bowler. The basic aerodynamic principles responsible for
the non-linear flight or swing of a cricket ball and the parameters that
affect it will be discussed in detail. This will include both, conventional
swing and the relatively new concept of reverse swing as produced by the
medium to fast bowlers. The concept of spin swing obtained by the slower
spin bowlers will also be discussed briefly.
The discussions will be largely based on results from several wind
tunnel tests conducted on real cricket balls. The possibilities of
applying the results from these tests to actual practical applications on
the cricket ground will also be discussed. This will include both, legal
and illegal equipment and procedures. In particular, the recent uproar over
ball tampering and its possible effects on swing will be covered in detail.

14.40 Tea

15.00 The playing quality of football pitches
Dr Steve Baker
The Sports Turf Research Institute, Bingley, West Yorkshire, BD16 1A=

ABSTRACT: Soccer players are highly sensitive to the physical properties
of the playing surface, most notably in terms of traction (or grip),
hardness for running and falling and the interaction of the ball with the
surface ie bounce and pace. Recognition of htese components of playing
quality has led to the development of a wide variety of measurement
techniques to quantify the playing characteristics of pitches. Measurement
techniques for ball/surface interaction and player/surface interaction are
considered and examples are given on the effect of construction methods on
playing performance.

15.40 The application of mathematical methods in running
Dr A.J. Ward-Smith
Department of Mechanical Engineering, Brunel University, Uxbridge,
Middlesex,UB8 3PH.

ABSTRACT: There are two broad approaches; one is based on the application
of Newton's laws of motion, the second on energy considerations. Both
approaches will be briefly reviewed. A more extensive presentation of
methods based on the first law of thermodynamics will then follow. The aim
of such methods is to identify all the important terms which contribute to
the overall energy balance of the runner, and to represent each by an
appropriate mathematical formulation. In practice, rather than dealing with
the energy equation directly, it is easier to deal with the rate of change
of energy, or power, and to derive the energy equation by integration of
the power equation. In principle, these equations can be applied to an
individual athlete to predict his/her performance from measured laboratory
data, or to provide representative data over a class of athletes, such as
world or Olympic champions.
The power equation can be integrated numerically to derive, for
example, the velocity=1Etime history for a 100 metre sprint. Alternatively,
by the introduction of some simplifications, a good correlation of
performances over a wide range of distances can be achieved. For example,
world- or Olympic-record performances over distances from 100 m to 10,000 m
are correlated by an equation of the form,

where X is the race distance, T is time, and a,b,c,d and l are constants.
Here a,b and l depend on the rate of chemical energy conversion, c on the
rate of heat production and d on the rate of working against aerodynamic
drag. The application of the above model to both male and female
performance will be considered.
For sprinting the theory allows the effects of wind assistance to
be investigated, and this is an area which will be discussed in detail.
Another field to which the model has been applied is hurdling, and this
topic will also receive consideration.

16.20 The first ninety degrees of the golf swing
Professor A.B. Turner
School of Engineering, University of Sussex at Brighton, Falmer,
Brighton, BN1 9QT

ABSTRACT: It is over 25 years since The Search for the perfect Swing was
published - arguably the best golf book ever. This comprehensive and quite
original work demolished many pet theories and at the same time confirmed a
number of suspicions. Amongst other things the research revealed
experimentally the essential features of a first class golf swing and
formulated them in terms of a "model golfer". Although they analysed the
golf swing quite exhaustively, it was left to the reader to determine for
himself how best to actually achieve this model swing, especially the "top
of the backswing" position. This position, generally accepted as the ideal
from which to deliver a powerful and accurate blow to the golf ball, is
discussed in terms of force and inertia and why it should be the ideal,
despite there being so many expert golfers who deviate from it.
The bulk of the paper is concerned with an attempt to take a closer
look at the first part of the backswing in terms of biomechanics. The
strong influence of the relative hand=1Fclubshaft alignment to the target at
the 90=B0 position on the ideal "top of the backswing" alignment is
discussed. A halogen beam producing a thin sheet of light, has been used
to simulate the swing plane, originally visualised by Ben Hogan as a sheet
of glass, aligned to the target.
The actions of several golfers, from the expert to the duffer, have
been photographed relative to the swing plane and the 90=B0 positions
correlated against the type of flight of the ball (slice/hook). From a
biomechanical analysis suggestions are put forward which may enable the
golfer to concentrate on, or experiment with, certain early positions in
the golf swing to enable him to achieve the golf ball flight desired.

16.40 General discussion and finish

Dr. Stephen Haake,
Department of Mechanical and Process Engineering,
The University of Sheffield,
Mappin Street,
PO BOX 600,
S1 4DU,
United Kingdom.