Download Angular Motion Vocabulary

1. Angular Acceleration- The rate of change of the angular velocity of a rotating body.
2. Angular Displacement- The angle in radians (degrees, revolutions) through which a point or line
has been rotated.
3. Angular Momentum- The quantity of rotation of a body, which is the product of its moment of
inertia and its angular speed.
4. Angular Speed- Change of angle per unit time, measured in radians
5. Arc Length- The length of a curve, measured in meters (the radius multiplied by Pi).
6. Center of Mass- A point representing the mean position of the matter in a body or system.
7. Centrifugal Acceleration- The apparent acceleration, equal in magnitude and opposite in direction
to the centripetal acceleration, drawing a rotating body away from the center of rotation, caused by
the inertia of the body.
8. Centrifugal Force- An apparent force that acts outward on a body moving around a center, arising
from the body's inertia.
9. Centripetal Force- A force that acts on a body moving in a circular path and is directed toward the
center around which the body is moving.
10. Centripetal Acceleration- The acceleration toward the center of rotation that holds an object in its
circular motion
11. Gravitational Force- the force of attraction between all masses in the universe.
12. Moment of Inertia- A quantity expressing a body's tendency to resist angular acceleration
13. Radian- The ratio of the arc length to the radius of the curve. Radian describes the angle subtended
by a circular arc as the length of the arc divided by the radius. A Radian describes the unit of angle,
equal to an angle at the center of a circle whose arc is equal in length to the radius.
14. Rotational Dynamics- The action of forces and torques on rigid objects as they rotate.
15. Rotational Kinetic Energy- Angular kinetic energy, Kinetic energy due to the rotation of an object
and is part of its total kinetic energy.
16. Rotational Motion- Rotation around a fixed axis.
17. Tangential Acceleration- Acceleration is the rate of change of velocity over time with a direction
that is tangent to the curve.
18. Tangential Speed- The speed of an object that is tangent to the object’s circular path.
19. Torque- A twisting force that tends to cause rotation.
20. Universal Gravitation Constant- the universal constant relating force to mass and distance in
Newton's law of gravitation
Johannes Kepler published his first two laws about planetary motion in 1609, having derived them by
analyzing the astronomical observations painstakingly collected by Tycho Brahe and his sister
Sophie Brahe, without the aid of a telescope. Kepler's third law was published in 1619. Johannes
Kepler developed these laws for orbits around the sun, but they apply to satellite orbits as well.
1. The Law of Orbits: All planets move in elliptical orbits, with the sun at one focus.
2. The Law of Areas: A line that connects a planet to the sun sweeps out equal areas in equal times.
3. The Law of Periods: The square of the period of any planet is proportional to the cube of the semimajor
axis of its orbit.
Referenced:
http://hyperphysics.phy-astr.gsu.edu/hbase/orbit.html#orbcon (June 21, 2014)
Kepler’s Laws, http://hyperphysics.phy-astr.gsu.edu/hbase/kepler.html#c1; June 21, 2014