Uniform Circular Motion

Gerak melingkar beraturan tuh..artinya gerakan benda yang melingkar dengan laju tetap.Coba kalian lihat, kalo ada benda yang bergerak melingkar beraturan, so pasti arahnya berubah tapi teratur.
Pada posisi manapun, benda itu bergerak dengan arah menyinggung terhadap putarannya.
Karena arah vektor kecepatannya sama persis dengan arah gerak benda, maka vektor kecepatan menyinggung terhadap gerak melingkarnya, betul2 menyinggung (arah tangensial). Perhatikan ajach animasi di atas, jelas toh... arah vektornya
Nah, sekarang terjemahin ya.. tulisan berikut (maksudnya..klik lanjuuuuttt......)


An object moving in a circle is accelerating. Accelerating objects are objects which are changing their velocity - either the speed (i.e., magnitude of the velocity vector) or the direction. An object undergoing uniform circular motion is moving with a constant speed. Nonetheless, it is accelerating due to its change in direction. The direction of the acceleration is inwards. The animation at the right depicts this by means of a vector arrow.

The final motion characteristic for an object undergoing uniform circular motion is the net force. The net force acting upon such an object is directed towards the center of the circle. The net force is said to be an inward or centripetal force. Without such an inward force, an object would continue in a straight line, never deviating from its direction. Yet, with the inward net force directed perpendicular to the velocity vector, the object is always changing its direction and undergoing an inward acceleration.

Source : The Physics Classroom : a highschool physics tutorial