A centrifuge is a common laboratory instrument that separates components of differing densities in solution. This is accomplished by spinning a sample around in a circle with a large angular speed. Suppose that after a centrifuge in a medical laboratory is turned off, it continues to rotate with a constant angular deceleration for 10.0s before coming to rest.

a.If its initial angular speed was 3890rpm , what is the magnitude of its angular deceleration?

b. How many revolutions did the centrifuge complete after being turned off?

Respuesta :

To solve this problem we turn to the kinematic equations of angular motion.

Through them we know that the change in angular acceleration is equal to the change in velocity over a certain time, that is,

[tex]\alpha = \frac{\Delta \omega}{t}[/tex]

[tex]\alpha = \frac{\omega-\omega_0}{t}[/tex]

The information provided says that the initial angular velocity is 3890, and the final is 0 (idle)

In this way,

[tex]\alpha = \frac{0-3890/60}{10}[/tex]

It is divided by 10 because the revolutions are in minutes and the time is given in seconds.

[tex]\alpha = 6.48rev/s^2[/tex]

B) To find the number of revolutions, we know that the angular velocity is equal to the displacement in a given time, that is,

[tex]\Delta \theta = \frac{1}{2} (\omega+\omega_0)t[/tex]

[tex]\Delta \theta = \frac{1}{2} (3890/60)(10)[/tex]

[tex]\Delta \theta = 324.17rev[/tex]

The rate of deceleration  is 23293 rev/min^2 while the number of revolutions is 325 rev

What is angular velocity?

The angular velocity is the ratio of the angle turned to the time taken. We have the following information from the question;

ω1 = 3890rpm

ω2 = 0 rpm

t = 10 s or 0.167 mins

α = ?

Using;

ω2 = ω1 - αt

0 = 3890 - 0.167α

α = 3890/0.167 = 23293 rev/min^2

Also;

θ = [(ω1 + ω2)/2]t

θ = [(0 + 3890)/2] 0.167 mins

θ = 325 rev

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