1) A centrifuge in a medical laboratory rotates at an angular
speed of 3,650 rev/min. When switched off, it rotates through 54.0
revolutions before coming to rest. Find the constant angular
acceleration (in rad/s2) of the
2) The diameters of the main rotor and tail rotor of a single-engine helicopter are 7.59 m and 0.98 m, respectively. The respective rotational speeds are 451 rev/min and 4,132 rev/min. Calculate the speeds of the tips of both rotors.
|main rotor||1 m/s|
|tail rotor||2 m/s|
Compare these speeds with the speed of sound, 343 m/s.
|vmain rotor / vsound||=||3|
|vtail rotor / vsound||=||4|
0^2 = 3650^2 + 2a * 54.0
a = - 1.23 * 10^5 rev / min^2.
One rotation of tip of main rotor = 7.59m * pi = 23.83m
451 * 23.83 = 10748.5 m/minute
10748.5 / 60 seconds per minute = 179.14 m/second
One rotation of tip of tail rotor = .98m * pi = 3.07m
4132 * 3.07 = 12658.24 m/minute
12658.24 / 60 seconds per minute = 211.42 m/second
main rotor 179.14 m/s
tail rotor 211.42 m/s
vmain rotor / vsound =0.522
vtail rotor / vsound=0.616
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