Circular motion occurs when an object angle of velocity is constantly changing. This means the object is always accelerating, whether or not it is actually speeding up, since its direction is changing. While the speed of the object is tangential always, it turns because of a force toward the center of the path of motion, causing a centripetal acceleration.
Uniform Circular Motion
When an object's motion is circular, its net force is toward the center of the path of motion, or the circle. The constant change the direction of the object is called centripetal acceleration. The speed itself is always tangential to the circle.
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Universal Gravitation
Universal gravitation describes how the force of gravity is affecting objects in orbit around the earth. While we are used to the equation for Force of Gravity being: Fg = m*g , after a certain point, gravity's acceleration is not the same as it is on the surface of earth. This is because the radius of circular motion affects the net force and acceleration on the object, which can be proven using the above equation for centripetal acceleration. Thus, the universal gravitational constant and its equation help us measure the force of gravity when an object is not necessarily on the surface of earth:
- Fg = G * (m1*m2) / r^2
- G = gravitational constant -- 6.67*10^-11 m^3 / kg*s^2
- m1 = mass 1
- m2 = mass 2 (one of these masses is the earth in the context of orbitals)
- r = radius