A compact disk rotates from rest to 420 rev/min in 4.5 seconds. (a) How far does a point on the edge of the disk, radius 8.0 cm, travel during this interval? (b) If the disk has mass of 18.2 grams, what is its kinetic energy when rotating at 400 rev/min? (I = MR2) (c) What average power is needed to accelerate the disk to 420rev/min in 4.5 seconds?
Rigid Body
A rigid body is an object which does not change its shape or undergo any significant deformation due to an external force or movement. Mathematically speaking, the distance between any two points inside the body doesn't change in any situation.
Rigid Body Dynamics
Rigid bodies are defined as inelastic shapes with negligible deformation, giving them an unchanging center of mass. It is also generally assumed that the mass of a rigid body is uniformly distributed. This property of rigid bodies comes in handy when we deal with concepts like momentum, angular momentum, force and torque. The study of these properties – viz., force, torque, momentum, and angular momentum – of a rigid body, is collectively known as rigid body dynamics (RBD).
B. A compact disk rotates from rest to 420 rev/min in 4.5 seconds.
(a) How far does a point on the edge of the disk, radius 8.0 cm, travel during this interval?
(b) If the disk has mass of 18.2 grams, what is its kinetic energy when rotating at 400 rev/min? (I = MR2)
(c) What average power is needed to accelerate the disk to 420rev/min in 4.5 seconds?
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