Rotational Motion

Classical Mechanics Related courses: /circles-geometry

5 flashcards · Physics · by lakesare

1. What's angular velocity?

   ω[radians/second] - (final angle) - (initial angle) / time = change in position/time ω = θ / t ω = angular speed in radians/sec θ = angle in radians (2π radians = 360 degrees) t = time, sec Angular speed and angular velocity use the same formula; the difference between the two is that Angular speed is a scalar quantity, while angular velocity is a vector quantity.

2. What's tangential velocity?

   When a body is moving in circular path at a distance r from its center its velocity at any instant will be directed tangentially.

3. A disc rotates at 33rpm, find its angular speed.

   33 revolutions/minute = (33 * 2Pi)radians / (60)s = (33 * 2Pi)/60 rad/s.

4. The earth rotates once on its axis every 24 hours. What is its angular speed?

   1 revolution / 24 hours = (2Pi)radians / (24 * 60 * 60)seconds = 7.27 * 10-5rad/s

5. How does tangential velocity relate to an angular speed?

   tangential speed = angular speed * distance from the center of the circle to the point Eg problem: An object attached to a string of length 1.5 m rotates at an angular velocity of 3.0 rev / s. For an object rotating about an axis, every point on the object has the same angular velocity. The tangential velocity of any point is proportional to its distance from the axis of rotation.