The shape of an ellipse is formed when a cone is cut at an angle. If you tilt a glass of water, the resulting shape of the surface of the water is also an ellipse. Ellipses can also be seen when a hula hoop or tire of a car is turned askew. Though these are examples of optical ellipses, the ellipse also has practical uses in real life.
Foods are cut to form ellipses. The shape offers a refined touch to simple foods. Cutting a carrot, cucumber or sausage at an angle to its main axis results in an elliptical slice. Wraps, tortillas wrapped around a filling such as chicken salad, are often cut into two elliptical wedges. The sharp focus of the ellipse gives an everyday food a more elegant look.
An ellipse has the property that if light or a sound wave emanates from one focus, it will be reflected to the other focus. A focus is one of two points that defines the shape and size of the ellipse. This property is used to create whispering galleries, which are structures that allow someone who is whispering in one area to be heard clearly by someone in another area but not by anyone else. Famous examples of whispering galleries include the United States Statuary Capitol Hall and London's St. Paul's Cathedral.
Lithotripsy is a method for destroying a kidney stone. The patient lies in an elliptical tub. The kidney stone is aligned to one of the foci of the ellipse. Shockwaves emanating from the other focus concentrate on the kidney stone, destroying it. The debris is as small as sand and can pass through the body without discomfort. In this treatment, no surgery is needed.
An elliptical training machine simulates the motion of running or climbing to provide the user with a healthful exercise without any impact on the joints. The foot of a user describes the shape of an ellipse as the machine is used. An elliptical machine can be motor-driven or user-driven, as well as dual action, where handlebars and leg mounts interdependently provide motion for each other. The elliptical trainer provides a stationary exercise for those who wish to avoid joint injury as a result of running.