Summary
Uniform circular motion considers an object’s circular path at a constant
speed. The velocity is not constant because the direction is always changing.
Because velocity changes, acceleration changes as well.
In uniform circular motion, velocity is directed tangent to the circle and
acceleration is directed toward the center.
Center of mass is the point where all of the mass of an object can be
considered to reside. For a homogeneous body, the center of mass is at the
geometric center of the object. For a group of objects, establish an x/y
coordinate system, multiply the position value of each object by its mass and
get the sum for all the particles. Divide this sum by the total mass. The
resulting value is the center of mass in terms of x- and y-coordinates. (Treat
the x-value and y-value separately.)
In an isolated system the center of mass will not accelerate.
Rotational dynamics involves describing the acceleration of an object in terms
of its mass (inertia) and the forces that act on it: Fnet = ma.
Torque is the quantity that measures how effectively a force causes rotation.
The greater the distance from the axis of rotation (the pivot) where force is
applied, the greater the torque will be.
Equilibrium refers to the state of an object when the sum of the forces and
torque acting on it is zero.
Angular momentum is the rotational analog for linear momentum. It is the
product of mass and velocity and the distance from the axis of rotation. It is
symbolized by L. Use the formula L = rmv⊥.
Conservation of angular momentum states that if the torques on a body balance
so that the net torque is zero, then the body’s angular momentum cannot change.
Rotational kinematics has symbols and concepts that are analogous to those of
linear kinematics.
When dealing with rotational kinematics, remember to use the Big Five to find
