rotational motion

• rotational motion (rotary motion) - a type of motion in which all points of a rigid body maintain a constant distance from an imaginary axis and rotate in circular paths
• angular position (θ) - a.k.a rotation angle is the amount of rotation taken by an object from its axis of rotation
• the unit of angular position is the radian (rad)
• a radian is an angle whose corresponding arc in a circle is equal to the radius of the circle.
• arc length is the measure of the distance traveled by a particle on a

  circular path
• radius is the measure of the distance of a particle from its axis of rotation.
• the rotation angle for one complete revolution is 360 degrees or 2pi radians
• dividing 360° by 2𝜋 we get the value of a radian which is equivalent to 57.3°
• 6.28 is the approximate value of 2π. Since π≈3.14
• for a rotating object, we define angular displacement as the difference between the final and initial position. It is a vector quantity with units of a radian.
• the angle is greater than zero if it moves in a counterclockwise direction (θ > 0)and less than zero in a clockwise direction (θ < 0).
• the rate of change of an object’s angular position concerning time is referred to as angular velocity represented by the symbol, omega, 𝜔
• the unit of measure for angular velocity is rad/s
• angular velocity, 𝜔 is the rotational equivalent of velocity 𝑣
• angular position in rotational motion is the equivalent of distance in linear motion
• the linear speed of an object is greater on the rim of any rotating object than near its axis of rotation
• the radius is directly proportional to velocity and inversely proportional to angular velocity or �� =𝑣𝜔.
• the rate of change of an object's angular velocity, 𝜔 in a given period,

  𝑡 is known as angular acceleration.
• the unit of angular acceleration is rad/𝑠2
• It is the rotational analog of acceleration 𝑎 in linear motion represented by the symbol alpha, 𝛼.
• the radius r is constant for circular motion