Ball Bounce Research Articles

Delayed rebounds in the two-ball bounce problem

In the classroom demonstration of a tennis ball dropped on top of a basketball, the surprisingly high bounce of the tennis ball is typically explained using momentum conservation for elastic collisions, with the basketball-floor collision treated as independent from the collision between the two balls. This textbook explanation is extended to inelastic collisions by including a coefficient of restitution. This independent contact model (ICM), as reviewed in this paper, is accurate for a wide variety of cases, even when the collisions are not truly independent. However, it is easy to explore situations that are not explained by the ICM, such as swapping the tennis ball for a ping-pong ball. In this paper, we study the conditions that lead to a ‘delayed rebound effect,’ a small first bounce followed by a higher second bounce, using techniques accessible to an undergraduate student. The dynamical model is based on the familiar solution of the damped harmonic oscillator. We focus on making the equations of motion dimensionless for numerical simulation, and reducing the number of parameters and initial conditions to emphasize universal behavior. The delayed rebound effect is found for a range of parameters, most commonly in cases where the first bounce is lower than the ICM prediction.

Effect of high knee running and high knee bounce skips exercises on running speed of 100 meters of athletic extracurricular participants in senior high school

Field tennis is a small ball game that requires a field and the players need a racket with its own string specifications. Like the Wilson NXT brand strings on the Wilson Hyper Hamer 7.5 racket, which has its own tension when it will receive the ball. To find out the tension of the strings, it is necessary to do a test. The experiment was carried out on the Wilson Hyper Hamer 7.5 racket with Wilson NXT brand strings against the Wilson ball and Nassau ball bounce. This research is a quantitative descriptive in which the data are analyzed by performing normality test, homogeneity test, and hypothesis testing. The normality test carried out showed that the Wilson XT brand string tension on the Wilson Hyper Homer 7.5 racket against the Dunlop ball and Nassau ball bounce had a significance of 0.05 and was categorized as normal. For the homogeneity test, it can be seen that the results of the Dunlop ball and Nassau ball bounce have a sig value p (0.31) so that the data is homogeneous. From the results of the t-test is 8.133 and the t table is 2.31 with a p significance value of 0.611.

Comparative analysis of wilson nxt brand string tension on wilson hyper hamer 7.5 racket against wilson and nassau ball bounce on court tennis

Field tennis is a small ball game that requires a field and the players need a racket with its own string specifications. Like the Wilson NXT brand strings on the Wilson Hyper Hamer 7.5 racket, which has its own tension when it will receive the ball. To find out the tension of the strings, it is necessary to do a test. The ball bounce data was collected at positions 0 to 7 positions with a racket tension of 50 lbs and analyzed by performing normality tests, homogeneity tests, and hypothesis testing. The normality test on these strings has a significance of 0.05 and is categorized as normal. Meanwhile, the homogeneity test can be seen that the results of the Dunlop ball and Nassau ball bounce have a value of sig. p 0.31 and the data is homogeneous. For the results of the t-test, it is known that the significance value of p is 0.611 and there is a significant difference. So, there is a correlation of the influence of the Wilson NXT brand string tension on the Wilson Hyper Homer 7.5 racket on the rebound of the Dunlop ball and the Nassau ball in tennis.

Improved gross motor skills of children aged 4- 6 years through shuttle run games and throwing bounce balls

Motor skills in children are a skill that every child must master. Having less than optimal gross motor activity makes children can interfere with activities in children. So it requires a solution to improve gross motor skills in order to develop optimally. This study aimed to find out the effectiveness of motor improvement in children aged 4-6 years. The research method used is Classroom Action Research, with data collection in this study using performance, observation, interviews, and documentation. The subjects of this study used a saturated sampling technique of 45 children of Mujahideen Kindergarten 2 Pontianak. Data analysis compares the results obtained from cycle I and cycle II with descriptive quantitative approaches. The results of this study showed an increase in children's gross motor skills through shuttle run games, and ball bounce throwing, evidenced by the number of students who increased their motor skills from 45 students from the first cycle of 16% or 16 students classified as good motor and in cycle II increased from 45 students 71% or 32 students fall into the category of good. Shuttle run and ball bounce throw are solutions to improve gross motor skills in children aged 4-6 years.

Dynamics of a bouncing table tennis ball from the acoustic signature using an optical fibre sensor

We describe an optical fibre-based method to estimate impact force and collision duration using time measurements recorded from acoustic signals of a table tennis ball bouncing on a table. The technique combines measurements obtained from a polarisation dependent optical fibre sensor with graphical analysis and kinetics through numerical calculations. The presented coefficient of restitution (COR), collision time, impact force, and elastic deformation during each bounce of the table tennis ball were obtained using corresponding time series measurements and numerical analysis. A peak impact force of 38.4 N was estimated for a ball of mass 2.83 g and 39.7 mm diameter dropped from a height of 31.5 cm. The impact duration for the associated bounce was 0.68 ms with a centre of gravity shift of 0.40 mm and COR of 0.88. While the observed results are unique to the ball and table surface, the approach is an attempt to fully quantify collision parameters from basic measurement and instrumentation applicable to undergraduate students. The sensor developed in this paper finds application in sports performance monitoring, infrastructural health early warning systems and pressure sensitive manufacturing processes.

The Effect of Wood Type on the Reflection of a Table Tennis Ball

The table tennis game table can be made of any material with certain bounce height requirements according to ITTF regulations. Wood as the main material for the table is found in Indonesia. Various types of wood have the potential to be a dining table material. This study was conducted to determine the effect of the type of wood on the bounce of a table tennis ball. Experiments were carried out on 9 types of wood, namely hardwoods (teak, sono, coconut), medium hardwoods (meranti, plywood and jackfruit) and soft woods (waru, randu and sengon). The height of the falling ball is determined to be 30 cm for the ball's bounce recorded by the camera. The ball used is a ball with a weight of 24 grams and 30 grams. Camera recording data is processed with Kinovea 08.15 to get the reflection height. The bounce height is used as a reference for ITTF standard compliance. The initial height and reflection height were then used to calculate the coefficient of restitution (COR). Data collection was carried out 5 times and the average value was calculated. The level of wood hardness is influenced by its specific gravity. Hard wood has a relatively high specific gravity. Teak wood which is relatively hard has a specific gravity value of 0.59 – 0.82 gr/cm3

Bounce of a biassed ball

If a smooth ball is dropped vertically without spin on a smooth horizontal surface then one might expect the ball to bounce vertically without spin. If it does not then the centre of mass of the ball does not coincide with its geometric centre. An experiment is described where a billiard ball and a superball are deliberately biassed by adding a small steel ball on one side. The results agree well with theoretical calculations.

Vertical bounce of a spinning ball

An experiment is described where three different spinning balls were dropped vertically on a horizontal surface, and the bounce was filmed with a video camera. The change in spin and horizontal speed of each ball was estimated theoretically, using equations familiar to physics students. The experiment provides an extension of the usual student exercise where a non-spinning ball is dropped vertically on a surface to measure the coefficient of restitution.

Serve routine preparation: Benefits of a combination of imagery, ball bounce and breathing on performance

The objective of this study was to test the benefit of consistent training in developing and using individualized service preparation routines composed in particular of motor imagery, ball bounce and breathing in order to provide practical recommendations to coaches. The results show an improvement in the percentage of first serve and effectiveness in experienced players.

Interspecific comparisons of C3 turfgrass for tennis use: II. Investigation of ball friction, ball bounce, and associated factors in replicated grass courts

AbstractTennis is played on many different surfaces including natural grass, which plays fast because of low ball bounce (i.e., coefficient of restitution [COR]) and low ball‐to‐surface friction (coefficient of friction [COF]) that increase the pace (ball speed) of tennis. Effects of various C3 turfgrasses on COF and COR have not been investigated. Our objectives were to evaluate eight cultivars of various species randomized within three official size tennis courts: (a) ‘Keeneland’ Kentucky bluegrass (Poa pratensis L., KB), (b) ‘Rubix’ KB, (c) ‘Villa’ velvet bentgrass (Agrostis canina L., VBG), (d) ‘Puritan’ colonial bentgrass (Agrostis capillaris L., CL), (e) ‘007’ creeping bentgrass (Agrostis stolonifera L., CB), (f) fine fescue (Festuca sp., FF) mixture, (g) ‘Karma’ perennial ryegrass (Lolium perenne L, PR), and (h) ‘Wicked’ PR. Friction was measured using a weighted sled and ball bounce (BB) to derive COR was measured using a vertical drop height of 254 cm. Bounce (i.e., COR) to satisfy the International Tennis Federation (ITF) minimum of 50% BB (COR = 0.70) was not observed on any of the species evaluated. Species such as FF and PR were able to achieve BB to satisfy the ITF 80% BB minimum to that observed on smooth concrete. Linear regression indicated that 170g of surface hardness for FF and PR to as much as 200g on KB and higher on BG may be needed to achieve a COR = 0.70. Hemi‐ and lignocellulose cell wall fractions were correlated with COR and COF but exhibited significant and opposite relationships. Achieving higher COF may be a more practical means to slow court pace of notoriously fast grass courts. Future research will be needed to investigate the effects of cultural practices on COF.

Will Musculoskeletal Conditions of Shoulder Affect the Hand Function and Hand-Eye Coordination? A Cross-Sectional Analysis

Objective: To analyze the Hand Function (HF) and Hand-Eye Coordination (HEC) among subjects with shoulder conditions resulting in pain and disability. Methodology: In these cross-sectional 47 subjects with selected shoulder pathology between 30 to 60 years participated. Shoulder pathology was measured in terms of pain and disability using the SPADI scale. These values were correlated with Purdue pegboard and Balloon tossing task and Wall Ball Bounce task. Results: Spearman rank correlation analysis of SPADI pain component revealed that there was a negative correlation with HF (R= -0.596, p<0.001), but there was significant correlation with HEC1 (R= -0.260, p= 0.078) and HEC2 (R= -0.217, p= -0.144). Though there was no correlation a negative relationship was observed between the variables. In the correlation of SPADI disability component there was a perfect negative correlation with HF (R= -0.870, p<0.001), with HEC1 (R= -0.588, p<0.001) and HEC2 (R= -0.541, p<0.001). Conclusion: This study concludes that shoulder pain negatively influences the Hand Function, whereas the shoulder disability negatively influences both Hand Function and Hand-Eye Coordination. The therapist should consider assessing and treating HF and HEC in patients with shoulder pain and disability in the future.

Development of an image processing-based ball tracking program for table tennis

Purpose The purpose of this study was to develop algorithms and software that can track the trajectory of table tennis balls using image-processing algorithms to obtain information quickly for under and establish tactics used in table tennis. Methods The algorithms used in the field of computer vision were applied on two matches played by novice and two matches during international competitions by elite athletes. Reliability analysis was performed by comparing the table tennis ball bounce frequency in each zone obtained through the automatic method and the manual method. Results The mean reliability of the two novice games was only 85.1 ± 3.69%, total error was 14.9 ± 3.69%, overestimation error was 52.2 ± 9.78%, and underestimation error was 47.8 ± 9.78%. While the mean reliability of the two international tournaments was 71.8 ± 0.87%, the total error was 28.2 ± 0.87%, overestimation error was 82.0 ± 8.03%, and underestimation error was 19.2 ± 7.75%. Conclusions Although the target reliability of algorithms and software developed in this study was achieved only in novice competitions with 80%, the over-estimation errors were generally high in international competitions, showing the potential for further improvement.

Predictive eye movements when hitting a bouncing ball

Predictive eye movements targeted toward the direction of ball bounce are a feature of gaze behavior when intercepting a target soon after it has bounced. However, there is conjecture over the exact location toward which these predictive eye movements are directed, and whether gaze during this period is moving or instead "lies in wait" for the ball to arrive. Therefore, the aim of this study was to further examine the location toward which predictive eye movements are made when hitting a bouncing ball. We tracked the eye and head movements of 23 novice participants who attempted to hit approaching tennis balls in a virtual environment. The balls differed in time from bounce to contact (300, 550, and 800 ms). Results revealed that participants made predictive saccades shortly before the ball bounced in two-thirds of all trials. These saccades were directed several degrees above the position at which the ball bounced, rather than toward the position at which it bounced or toward a position the ball would occupy shortly after the bounce. After the saccade, a separation of roles for the eyes and head ensured that gaze continued to change so that it was as close as possible to the ball soon after bounce. Smooth head movements were responsible for the immediate and ongoing changes in gaze to align it with the ball in the lateral direction, while eye movements realigned gaze with the ball in the vertical direction from approximately 100 ms after the ball changed its direction of motion after bounce. We conclude that predictive saccades direct gaze above the location at which the ball will bounce, presumably in order to facilitate ball tracking after the bounce.

The effects of skill-level and playing-position on the anticipation of ball-bounce in rugby union

The ability to anticipate is a defining feature of skilled sports performance. To date, research investigating the information that underpins skilled anticipation has focused on kinematic information from an opponent and contextual factors. However, there has been a paucity of research investigating the influence of ball-flight and spin. Oval shaped balls, despite the seeming random nature, do in fact display specific bounce characteristics based on the nature of ball-flight. We tested the ability of 38 professional (categorised in to 15 ‘backs’ and 23 ‘forwards’ based on their playing position) and 20 less-skilled rugby union players to anticipate ball bounce direction for grubber and chip kicks using a temporal occlusion paradigm to restrict access to different sources of information. We predicted that skilled performers would have become attuned to both advance postural cues and the physical laws of ball flight and spin that govern ball bounce through their extensive practice and exposure to these situations, and so would anticipate more accurately than less-skilled performers. Results supported this hypothesis as skilled participants outperformed less-skilled in all occlusion conditions, however all groups anticipated more accurately with access to later emerging information sources (i.e., ball spin and rotation) with the skill level difference primarily underpinned by earlier available sources (i.e., advance postural cues). There was no difference between anticipation accuracy in professional forwards and backs and no kick type x group interaction, suggesting that the knowledge structures underpinning perceptual-cognitive expertise are not position specific. Findings have implication for models of anticipation and training design and tactics in rugby.

Gender comparison in consistency in the basketball free throw by an event-driven approach

This paper compares the free-throw performance of men and women in the National Collegiate Athletic Association (NCAA), taking into account differences in ball size, ball stiffness, and release height. Although some claim that men are more athletic, based on the assumption that athleticism correlates with physical traits, the average free-throw percentages in NCAA Division 1 basketball have been close for decades and across gender. The larger men’s basketball could create a disadvantage for men. On the other hand, the stiffer women’s basketball could create a disadvantage for women. In addition, women typically launch the ball from a lower height above the floor than men do. Therefore, the question of which gender is more consistent was unanswered. To answer this question, we turned to simulations of basketball trajectories. We patched together closed-form trajectory events that terminate at the front rim, back rim, backboard, and a fictitious plane below the ring. This produced what we call speed lines. Using the speed lines and NCAA average free-throw percentages, the consistencies of men- and women-free throws were determined. Examination of the speed lines reveals that they exhibit fractal-like behavior. We analyzed sensitivities with respect to ball size, ball bounce, and release height. We found that the most influential factor in determining free-throw success is the average release height of a gender. Under the stipulated assumptions, this paper found that women are about 3% more consistent than men are.

Backward bounce of a spinning ball

A ball that is incident on a surface with backspin is likely to bounce backwards if it is incident at an angle near the normal. The effect is common in many ball sports, including cricket, tennis, baseball, golf, billiards etc. A particularly impressive feat in golf is to land the ball past the hole and let it bounce back towards the hole. The ball may even bounce forward several times before it bounces backward. The physics of a backward bounce is described in the present paper, including several experiments that would be suitable for a student exercise on the bounce of a spinning ball.

Measuring Canopy Anomaly Influence on Golf Putt Kinematics: Does Annual Bluegrass Influence Ball Roll Behavior?

Weedy annual bluegrass (Poa annua L.) has long been presumed to affect ball roll. However, no peer‐reviewed research has evaluated the impact of annual bluegrass or other putting green surface anomalies on ball roll direction. Results to date suggest that several sources of error must be controlled before influence of annual bluegrass on ball directional imprecision can be measured. By using a mechanical putter to avoid directional errors associated with simulated putt devices, selecting balanced golf balls, eliminating legacy effects of repeated ball rolls, and scoring ball direction 30 cm before terminal motion, we were able to limit ball directional imprecision to 4.9 mm m−1 on creeping bentgrass (Agrostis stolonifera L.) greens. When a mechanical putter was used to putt balls across 200 transects spanning eight greens at two Virginia golf courses, directional imprecision of ball roll increased from 4.9 mm m−1 on visibly pure creeping bentgrass to 13 mm m−1 when the balls traversed a small patch of annual bluegrass. Directional imprecision of balls rolled by the Greenstester was independent of annual bluegrass presence and ranged from 16 to 17 mm m−1. Ball bounce and acceleration was measured using a high‐speed camera and object‐tracking software. Annual bluegrass did not influence ball acceleration, but when balls were rolling over annual bluegrass or for the first decimeter after encountering annual bluegrass, ball bounce area was significantly increased. The increased ball bounce was presumably due to textural differences between annual bluegrass and creeping bentgrass and could have contributed to increased ball directional imprecision.

Contextual information and perceptual-cognitive expertise in a dynamic, temporally-constrained task.

Skilled performers extract and process postural information from an opponent during anticipation more effectively than their less-skilled counterparts. In contrast, the role and importance of contextual information in anticipation has received only minimal attention. We evaluate the importance of contextual information in anticipation and examine the underlying perceptual-cognitive processes. We present skilled and less-skilled tennis players with normal video or animated footage of the same rallies. In the animated condition, sequences were created using player movement and ball trajectory data, and postural information from the players was removed, constraining participants to anticipate based on contextual information alone. Participants judged ball bounce location of the opponent's final occluded shot. The 2 groups were more accurate than chance in both display conditions with skilled being more accurate than less-skilled (Exp. 1) participants. When anticipating based on contextual information alone, skilled participants employed different gaze behaviors to less-skilled counterparts and provided verbal reports of thoughts which were indicative of more thorough evaluation of contextual information (Exp. 2). Findings highlight the importance of both postural and contextual information in anticipation and indicate that perceptual-cognitive expertise is underpinned by processes that facilitate more effective processing of contextual information, in the absence of postural information. (PsycINFO Database Record

A comparison of service efficiency between players of male and female doubles at professional tennis tournaments

Male and female players have a different quality of service. For example, men can reach a higher service speed, or use more ball spin. Tennis service has also a different efficiency on different surfaces. Every surface has specific characteristics and has different effects on ball impact and ball bounce. The aim of our study was to compare the amount of service points won between male and female players in men’s and women’s doubles at ATP (Association of Tennis Professionals) and WTA (Women Tennis Association) tournaments on three different surfaces. We observed a total of 303 matches. Matches were played on clay, hard and grass courts. With the help of match records, we found that men won around 10% service points more than women. Results indicate that women’s doubles matches show greater differences in performance between opponents. Men also need to win more service points than women, to win a match. Fast surfaces provide a greater advantage for serving teams, both for men and women. The lowest serve efficiency was reached on clay (slow surface) both in the men’s and women’s doubles.

Predicting the timing of future events using sound: Bouncing balls and tone bursts

Listeners can predict the timing of the next bounce of a bouncing ball by sound alone with high accuracy, relying primarily on temporal cues [Giordano et al., 2011, JASA, 129, 2594]. The present study investigated the role of temporal structure (natural bouncing patterns versus artificially reversed bouncing patterns) and event type (ball bouncing sounds versus similarly patterned tone bursts). After listening to two to four such sounds, listeners would indicate when they expected the next sound to occur (without hearing it). Results replicate previous findings of high accuracy in predicting the timing of natural bounce patterns regardless of event type. In contrast, accuracy was substantially poorer when pattern timing was reversed. Nevertheless, even for reversed patterns, listener accuracy improved as a greater number of bounces were heard prior to response time. This suggests that with additional information listeners were able to utilize veridical acoustic cues that best fit the temporal pattern. These findings demonstrate that in addition to being highly adept in estimating future timing of natural auditory events, listeners (a) tend to rely on temporal dynamics of everyday events in their timing estimates, and (b) can modify their response strategies for artificial timing patterns.