Power generated by a topspin vs. a slice - PowerPoint Presentation

1. Power generated by a topspin vs. a slice Ali Kazmi April 30, 2012

2. Every human motion is driven by the synergistic action of the basic biomechanical unit. The basic biomechanical unit consists of a pair of mutually antagonistic muscles that produce a common muscular torque in the same jointIn tennis, the most obvious example is the biceps-triceps pair (pictured) Breaking Down a Shot 2from Ivancevic et al. (2008)An example of the basic mechanical unit

3. The three components of the kinetic chain (nervous, muscular, and skeletal systems) all work together to produce movement.Breaking Down a Shot 3

4. The standard forehand has two main phases: (i) preparation or “loading,” and (ii) hitting the ball.Includes two simultaneous actions: stepping into the right position with the left leg forward (if right-handed) and lifting the racquet above the shoulders Muscles involved: right deltoideus and biceps Breaking Down a Shot Preparation or “Loading” Hitting the BallIncludes three main movements:Right hip rotation towards the ball with feet still on the ground (muscles involved: right gluteus maximus and medius muscles)Arm swing of the racquet (Muscles involved: right pectoralis major, deltoideus, and biceps)To create topsin, a slight twist of the wrist to brush over the ball (muscles involved: right palmar flexors) 4Not pictured: gluteus maximus

5. The topspin is a forehand shot generated hitting the ball with an up-and-forward force that causes the ball to drop.“Topspin” refers to the property of a ball that rotates as if rolling in the same direction as its velocity. Topspin inflicts a downward force that causes the ball to drop due to its interaction with the air (called the Magnus effectBreaking Down a Shot What is “Topspin”?Use in TennisTopspin provides the player an increased margin of error because the ball hits the ground quicker, and so can rise higher above the netThe racquet should face below the direction the ball is moving, and brush up against the back of the ball5

6. The splice is a forehand shot that utilizes “backspin” to cause an upward force that lifts the ball. “Backspin” refers to the property of a ball that rotates as if rolling in a direction opposite to its velocityAn upward force is applied to the ball that lifts the ball (also due to the Magnus effect)Breaking Down a Shot What is “Backspin”?Use in TennisA splice is useful for defensive shots because the ball takes a longer time to reach the opponent, giving the player more timeBackspin shots also tend to bounce lower when the reach the opposite court. 6

7. Power Generation in a Topspin Stroke Power Analysis 7Initial Kinetic Energym= 0.057kgX-velocity= 0.937m/sY-velocity = 0.912m/sOverall velocity= 1.31m/sg=10m/s2h= 0.9213mKE= ½*m*v2 =0.050JPE= mgh= 0.53Total Energy= 0.58 Final Kinetic Energy m= 0.057kgX-velocity= 28.973m/sY-velocity = 2.517m/sOverall velocity= 29.08m/sg=10m/s2h= .9213mKE= ½*m*v2= 24.1JPE=mgh= 0.53JTotal Energy= 24.6JInstantaneous Power = Change in EnergyPower Generated= 24.02W

8. Power Generation in a Slice Initial Kinetic Energym= 0.057kgX-velocity= 0.863m/sY-velocity = 0.814m/sOverall velocity= 1.19m/sg=10m/s2h= 1.051mKE= ½*m*v2 =0.040JPE= mgh= 0.60JTotal Energy= 0.64JPower Analysis Instantaneous Power = Change in Energy8Final Kinetic Energy m= 0.057kgX-velocity= 24.096m/sY-velocity = 2.170m/sOverall velocity= 24.2m/sg=10m/s2h= 1.051mKE= ½*m*v2= 16.7JPE=mgh= 0.60JTotal Energy= 17.3JPower Generated= 16.66W

9. Further detailed analysis of impact rotation kinetic energy changes Energy transfer measurementsStrategic considerations Impact of elasticity of strings of racquet Frequency of usage of different types of shots and success/failure ratios Future Directions9

10. Elliott, B. "Biomechanics and Tennis." British Journal of Sports Medicine 40.5 (2006): 392-96. Print.Ivancevic, T. “Biomechanical Analysis of Shots and Ball Motion in Tennis and the Analogy with Handball Throws.” Physical Education and Sport 6.1 (2008): 51-66. Print References 10