An old fashion record rotates at a constant rate of 33 rpm. a) What is its angul
ID: 1306162 • Letter: A
Question
An old fashion record rotates at a constant rate of 33 rpm.
a) What is its angular speed in rad/s?
b) If the record has a radius of 18 cm, what is the linear speed of a point located at its edge?
c) A which distance from the center is located a point which has a quarter of its linear speed?
d) Find the angular displacement (in rad) and distance travelled by these 2 points (in meters) on the
record if the music plays for 20 min.
e) If it takes 3 seconds for the record to attain this constant rotation rate, what is its angular
acceleration?
Explanation / Answer
a) w = 33 rpm = 33*2*pi/60 = 3.454 rad/s
b) v = r*w = 0.18*3.454 = 0.62172 m/s
c) r' = 18/4 = 4.5 cm
d) s1 = v1*t = 0.62172*20*60 = 746.064 m
s2 = v2*t = 0.045*3.454*20*60 = 186.516 m
e) alfa = dw/dt
= 3.454/3
= 1.1513 rad/s^2