Centrifuge Revolution Calculation

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In summary, the conversation discusses the operation of a centrifuge with a sample of blood to determine the necessary revolutions per second for the red blood cells to settle out of the plasma. The solution involves using the formula F=m(v^2/r) and calculating the circumference to obtain the answer in revolutions per second.
  • #1
je55ica7
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A sample of blood is placed in a centrifuge of radius 16.0 cm. The mass of a red blood cell is 3.0e-16 kg, and the magnitude of the force acting on it as it settles out of the plasma is 4.0e-11 N. At how many revolutions per second should the centrifuge be operated?

I can figure out the velocity... but the answer needs to be in revolutions per second. Would I just divide the velocity by the circumference of the centrifuge??
 
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  • #2
je55ica7 said:
I can figure out the velocity... but the answer needs to be in revolutions per second. Would I just divide the velocity by the circumference of the centrifuge??
That's correct.
 
  • #3
Ok, I figured out the problem using F=m(v^2/r). I got the right answer when I kept the mass in kg and solved for v. How could that be right if the answer had to be in rev/s? I don't get it...
 
  • #4
Calculate the circumference and you'll get it. :wink:
 
  • #5
Lol

Soooo sneaky... hehe
 

1. What is a centrifuge and how does it work?

A centrifuge is a laboratory instrument used to separate components of a mixture based on their density. It works by spinning samples at a high speed, causing the denser components to move towards the bottom while the less dense components stay closer to the top.

2. What are the common uses of a centrifuge in scientific research?

A centrifuge is commonly used in scientific research for various purposes, including separating blood components for analysis, isolating DNA and RNA, purifying proteins, and separating cells or organelles.

3. How do you calculate the relative centrifugal force (RCF) of a centrifuge?

The RCF of a centrifuge is calculated by multiplying the radius of the rotor in centimeters by the square of the speed in revolutions per minute (RPM) and dividing by 11.18. This formula can be written as RCF = (1.12 x 10^-5) x (radius in cm) x (RPM)^2.

4. What factors can affect the performance of a centrifuge?

The performance of a centrifuge can be affected by several factors, such as the speed and duration of spinning, the type and size of the samples, the temperature and viscosity of the samples, and the balance and alignment of the rotor.

5. How do you maintain and clean a centrifuge?

To maintain a centrifuge, it is important to regularly clean the rotor and chamber with a disinfectant solution, check and replace worn out parts, and perform routine maintenance according to the manufacturer's instructions. It is also crucial to balance the samples properly and use appropriate containers to prevent contamination.

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