Why?

            Physics, a branch of science, is traditionally defined as the study of.
             matter, energy, and the relation between them. The interaction between matter.
             and energy is found everywhere. In order for matter to move, it requires some.
             form of energy.
             Sports show many good examples of the relationship between matter and.
             energy. For instance, a pitcher requires energy to throw a baseball at the.
             incredible speed and accuracy that is needed to keep the batter from using his.
             energy to try and hit the ball. The batter exhibits the need for a certain.
             trajectory because he/she needs to hit the ball hard enough and keep it high.
             enough to sail over the outfield wall. On the other hand, the batter must be.
             certain to keep the trajectory low enough so that the ball will reach the fence.
             Trajectory is also seen in basketball, where players must shoot the ball with.
             enough arch to get over the front of the rim, and go through the hoop. The.
             energy required to do this comes from not only the arms, but the legs as well.
             The medical field has seen enormous breakthroughs because of principles.
             of physics. Doctors are now able to use lasers for surgery. Lasers are based.
             on the physical principle of light, and are devices for the creation and.
             amplification of a narrow, intense beam of coherent light. New laser.
             microsurgery can actually alter the shape of the cornea in the eye so the.
             patient's eyesight can return to normal, and he/she will no longer need those.
             bothersome glasses. Ultrasound is used in the medical field for destroying.
             various unwanted substances in the body such as kidney stones. Ultrasound uses.
             sound waves to dissolve these foreign bodies. If not for physics, ultrasounds.
             would never have been discovered and utilized. MRI scans, another new.
             discovery, are able to show a complete three dimensional picture of the.
             interior structure of the body, and are extremely valuable in hospitals. These.
             scans are based on the principles of electromagnetism, and the phenomenon that.