A Determination of Velocities and Angles of Projection for the Tennis Serve

Abstract

The purpose of this study was to determine the minimum and maximum velocity of the tennis ball for selected heights of contact and angles of projection and wall impact points during the tennis serve. By use of a ballistics formula, a number of variables which determine the trajectory of the tennis ball were programed for the computer. Tables were tabulated and are available for all data gathered. Angles of projection from the horizontal were selected to range from ?5° to 15° in increments of 1°. Velocity of the serve ranged from a low of 30 ft. per second to a high of 176 ft. per second. Finally, the height of the contact point ranged from a low of 6.0 ft. to a high of 9.0 ft. in increments of .5 ft. Height of the ball when crossing the net (impact point on the practice court) ranged from a low of 3.01 ft. to a high of 8.47 ft. The minimum height at crossing was achieved at 6.5 ft. service height, a ?3° angle of projection and time from baseline of .30 sec. This is a relatively high velocity serve. In contrast, the maximum height over the net of 8.47 ft. was achieved at an 8.5 ft. service height, a 15° angle of projection, and time of .79 sec. to point of impact. These data indicate that at higher service heights and slower velocities, a ball can hit the impact area as much as 8.47 ft. from the floor, 4.47 ft. above the net and still remain in the service court.     

Exploring the Effects of Television Viewing on Perceived Life Quality: A Combined Perspective of Material Value and Upward Social Comparison

American television programs have been criticized for being filled with images endorsing capitalist consumerism and for being weighted toward the upper middle classes. This study proposed that heavy viewing of these distorted representations may culminate in decreases in viewers' life satisfaction. A path model investigated this supposition, based on material value and social comparison perspectives. Surveys were administered to 225 adults in a northeastern town in the United States, and the data were subjected to path analysis. The findings of this study suggest that heavy television viewing may be associated with material value, estimates of other people's affluence, and perceived gaps between the self and others in material affluence. Of importance, the findings also suggest that the perceived gaps between the self and others may be associated both with dissatisfaction with personal life and dissatisfaction with current social equality, whereas material value may be associated only with dissatisfaction with personal life.     

Implementing the UN Decade of Education for Sustainable Development (DESD): achievements, open questions and strategies for the way forward

This paper looks at the implementation of the DESD from a global perspective. It takes the position that quality education is fundamental for learning how to live sustainably, and that the DESD needs to be better positioned in the education landscape and conceived as a global social movement that must be fostered and nurtured for the well-being of humankind. It suggests that, while there has been progress, much remains to be achieved. Several key challenges are identified. With regard to overcoming these obstacles, it focuses on macro-level strategies that would allow the development of environments in which actions can take root and grow so that the work of the DESD endures beyond the decade itself. Finally, it suggests that there are some opportunities that can be seized to make the task ahead easier to accomplish.     

A consideration of five traditional educational philosophies for speech communication

The authors present five traditional educational philosophies— Idealism, Realism, Neo‐Thomism, Experimentalism, Existentialism—which identify an instructor's educational approaches to speech communication.     

My system of career influences: responding to challenges facing career education

The present article explores major challenges facing career psychology, specifically within the field of career education. Several issues are identified including the need for more effective links between theory and practice, the movement towards constructivist theories and the related challenges of applying such theories. These issues are explored within the context of the reformulation of career education and through the lens of the constructivist Systems Theory Framework of career development and its applied activity, the My Systems of Career Influences.

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Zusammenfassung “My System of Career Influences”: Eine Antwort auf Herausforderungen für den Berufswahlunterricht. Dieser Artikel untersucht wesentliche Herausforderungen für die Berufspsychologie, insbesondere auf dem Gebiet des Berufswahlunterrichts. Mehrere Aspekte werden angesprochen, unter anderem der Bedarf für wirkungsvollere Verknüpfungen von Theorie und Praxis, den Trend zu konstruktivistischen Theorien und der Anwendung solcher Theorien. Diese Aspekte werden untersucht vor dem Hintergrund einer Neuformulierung der Berufswahlvorbereitung, sowie aus dem Blickwinkel des konstruktivistischen System-Theorie-Modell (Systems Theory Framework) und dessen Anwendungskonzept, dem ″My Systems of Career Influences” (Meine Systematik für Berufswahl-Einflüsse).

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Resumen Mi Sistema de Influencias sobre la Carrera: Respuesta a los Retos que afronta la Educación para la Carrera. El presente artículo explora los principales retos a los que se enfrenta la psicología de la carrera, en concreto dentro del campo de la educación para la carera. Se identifican varias cuestiones tales como la necesidad de vínculos más efectivos entre la teoría y la práctica, el movimiento hacia teorías constructivistas y los retos derivados de la aplicación de dichas teorías. Estas cuestiones se abordan dentro del contexto de reformulación de la educación para la carrera y a través del lente del marco constructivista de la Teoría de Sistemas del desarrollo de la carrera y su aplicación práctica, Mi Sistema de Influencias sobre la Carrera.

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Résumé Mon Système d’Influences sur la Trajectoire Vocationnelle: une réponse aux défis lancés à l’éducation au choix vocationnel. Le présent article explore les défis majeurs lancés à la psychologie vocationnelle, en particulier dans le champ de l’éducation au choix vocationnel. On identifie plusieurs questions comme la nécessité de liens plus fermes entre théorie et pratique, l’expansion des théories constructivistes et les défis que leur application implique. Ces questions sont explorées dans le contexte de la reformulation de l’éducation au choix professionnel et sous l’angle de la structure constructiviste de la Théorie des Systèmes du développement vocationnel et de son application “Mes Systèmes d’Influences sur la Trajectoire Vocationnelle”.

     

Vital pathways for hospital librarians: present and future roles

Objectives:

The research objectives were to (1) describe the current and future roles of hospital librarians and the challenges they face and (2) find evidence supporting the hypothesis that librarians are essential to hospitals in achieving the organizations'' mission-critical goals.

Method:

The authors used results from a previous research study that identified the five organizational mission-critical goals important to hospital administrators and then searched the literature and solicited examples from hospital librarians to describe the librarian''s role in helping hospitals achieve these goals.

Results:

The literature supports the hypothesis that hospital librarians play important roles in the success of the hospital. Librarians support quality clinical care, efficient and effective hospital operations, continuing education for staff, research and innovation, and patient, family, and community health information needs.

Conclusion:

Hospital librarians fulfill many mission-critical roles in today''s hospital, providing the right information at the right time in a variety of ways to enhance hospital and medical staff effectiveness, optimize patient care, improve patient outcomes, and increase patient and family satisfaction with the hospital and its services. Because hospital librarians and their services provide an excellent return on investment for the hospital and help the hospital keep its competitive edge, hospital staff should have access to the services of a professional librarian.

Highlights

• A review of the literature supports the hypothesis that services of the professional librarian result in:
  • enhanced staff effectiveness,
  • optimized patient care,
  • improved patient outcomes, and
  • increased patient and family satisfaction with the hospital and its services.

Implications

• Because hospital librarians and their services provide an excellent return on investment for the hospital and help the hospital keep its competitive edge, hospital staff should have access to the services of a professional librarian.

     

When Parents Ask ... about Preterm Birth, Breastfeeding Success, Breast Cancer, or Waterbirth

IN THIS COLUMN, THE AUTHOR REVIEWS RESEARCH ON FOUR SEPARATE TOPICS: the prevention of preterm birth, the effect of epidurals on breastfeeding success, the possible protective effect of lactation on breast cancer, and laboring in water. In two separate studies-a multisite study in the United States and a second study from Brazil-natural progesterone was shown to significantly reduce the incidence of preterm birth in women at high risk. A third study conducted in the United Kingdom examined the effect of clindamycin on preventing infection that can lead to preterm birth. A group of studies related to lactation found that early breastfeeding was more successful in women who did not have epidural anesthesia. In a Korean study, the lifetime duration of breastfeeding was associated with a significant reduction in breast cancer. Concerning waterbirth, Swiss researchers found that, when a woman labored in water, she regulated both water temperature and bathing duration to ensure that her body temperature and that of the fetus remained within a normal physiological range.