Posted by mymi on Friday, October 21, 2011 at 12:15am.
In a tape recorder, the magnetic tape moves at a constant linear speed of 5.6 cm/s. To maintain this constant linear speed, the angular speed of the driving spool (the takeup spool) has to change accordingly.
(a) What is the angular speed of the takeup spool when it is empty, with radius r1 = 0.79 cm?
(b) What is the angular speed when the spool is full, with radius r2 = 2.32 cm?
(c) If the total length of the tape is 100.8 m, what is the average angular acceleration of the takeup spool while the tape is being played?

Physics  Henry, Saturday, October 22, 2011 at 5:54pm
a. C=pi*D = 3.14 * (2*0.79) = 4.96 cm.
V=5.6cm/s * 6.28rad/4.96cm = 7.1rad/s.
b. C = 3.14 * (2*2.32) = 14.57 cm.
V = 5.6cm * 6.28rad/14.57cm = 2.4rad/s. 
Physics  Long, Sunday, October 23, 2011 at 7:33pm
C. 0.00294 rad/s^2

Physics  Long, Sunday, October 23, 2011 at 8:07pm
C. 100.8 1m*100cm/m /5.6 cm/s = 1800s
(7.12.4)rad/s/1800s =.00261 rad/s^2