Presentation on theme: "And other weird, wild stuff.. Circular Motion Uniform Circular Motion Movement of an object around a fixed radius Also at a fixed speed. Does an object."— Presentation transcript:
And other weird, wild stuff.
Circular Motion Uniform Circular Motion Movement of an object around a fixed radius Also at a fixed speed. Does an object going around in a circle accelerate? YES! It changes direction constantly!
B. Direction is important If the object is going in a circle, what direction does the acceleration go? R r VcVc AcAc TOWARDS THE CENTER! ALWAYS, ALWAYS, ALWAYS! P.S. A c and V c are at 90°
C. FORMULAS V c = 2π r t V c is called centripetal velocity a c = v c 2 r a c is called centripetal acceleration
II. Centripetal Force According to Newton’s 2 nd Law F= ma So, F c = ma c Or, F c = mv c 2 r Centripetal Force ALWAYS goes toward the center due to Newton’s 2nd Law.
III. Centrifugal Force A “fake” force. You are in a ride that goes in a circle. You feel like you are pushing against your seat. You are not It is your intertia……it is not a force
IV. Law of Gravitation Bob Newton Came up with it. The myth was he was hit in the head with an apple. Didn’t use an apple, used the moon. The moon is falling to Earth due to gravity The Earth is being pulled to the moon with the same gravity Why? NEWTON’S 3 rd Law Newton found out that the gravity is dependent upon the mass of the two objects and the distance between them.
B. FORMULA F g = Gm 1 m 2 r 2 m 1 and m 2 are the masses of the two objects r is the distance between the centers of the two objects. G= gravitational constant = 6.67 x By the way, This equation works anywhere in the universe.
C. Example What is the force of gravity (weight) of a 10 kg dog on Earth? (I would like you to do this 2 different ways.) You are going to need the following info: g = 9.8 m/s 2 Mass of Earth = 5.97 x kg Radius of earth = m