Question

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.

Part A

If its initial angular speed was 3890rpm , what is the magnitude of its angular deceleration? (|?| in revs/s^2 )

Part B

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

Answer 1

`a_r=389\ rev.s^(-2)`

`n=58350 rev`

Step-by-step explanation:

Given:

time of constant deceleration,
`t=10\ s`

A.

initial angular speed,
`N_i=3890\ rpm\`

Using equation of motion:

`N_f=N_i+a_r.t`

`0=3890+a_r* 10`

`a_r=389\ rev.s^(-2)`

B.

Using eq. of motion for no. of revolutions, we have:

`n=N_i.t+(1)/(2) a_r.t^2`

`n=3890* 10+0.5* 389* 100`

`n=58350\ rev`