best angle to release the ball is 30 degrees?

  How physics can improve your football (Jan 24)
  http://physicsweb.org/article/news/10/1/11

   New research on the mechanics of throwing could allow football teams to
   make greater use of "throw-ins". Two scientists at the University of
   Brunel in the UK have calculated that to launch a football as far as
   possible from a throw-in, the best angle to release the ball is 30
   degrees. The result differs significantly from the figure quoted in most
   physics textbooks (Sports Biomechanics in press).

.