Wednesday
August 27, 2014

Homework Help: physics - drwls?

Posted by winterWX on Monday, March 12, 2007 at 1:25am.

A disk rotates about its central axis starting from rest and accelerates with constant angular acceleration. At one time it is rotating at 7 rev/s. 55 revolutions later, its angular speed is 21 rev/s.
(a) Calculate the angular acceleration.
(b) Calculate the time required to complete the 55 revolutions mentioned.
(c) Calculate the time required to attain the 7 rev/s angular speed.
(d) Calculate the number of revolutions from rest until the time the disk attained the 7 rev/s angular speed.

(a) Divide the change in angular rotation rate by the time required for the acceleration to occur.
alpha = (14 rev/s)*(2 pi rad/rev)/Time
Since 55 revolutions were required and the average rotation rate was 14 rev/s, the time required was 55/14 = 3.93 s.
alpha = 22.4 rad/s^2
(b) already determined above
(c) It will take 1/2 as long to go from 0 to 7 rev/s as it takes to go from 7 ro 21 rev/s
(d) In radians, the answer is
(angle) = (1/2) alpha t^2, where t is the time you get in part (c). Divide by 2 pi for he number of revolutions

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

physics - A disk rotates about its central axis starting from rest and ...
physics - A disk rotates about its central axis starting from rest and ...
Physics - Starting from rest, a disk rotates about its central axis with ...
physics - starting from rest, a disk rotates about its central axis with ...
Physics - A spinning disk of mass 5.0 kg and radius 0.25m is rotating about an ...
physics - A spinning disk of mass 5.0 kg and radius 0.25m is rotating about an ...
physics - A compact disk player has just been turned off. A disk decelerates ...
Physics - A compact disk rotates from rest to 500 rev/min. in 5.5s. a) What is ...
Physics 203 ( College) - A disk of radius 12 cm, initially at rest, begins ...
physics - A 44.3-cm diameter disk rotates with a constant angular acceleration ...

Search
Members