🌀 Centrifuge Calculator
Calculate centrifuge forces
How to Use This Calculator
Enter RPM
Input the rotational speed in revolutions per minute (RPM). This is the speed at which the centrifuge rotates. For example, a laboratory centrifuge might run at 3000 RPM, while an ultracentrifuge might run at 100,000 RPM.
Enter Radius
Input the radius (r) in meters (m). This is the distance from the center of rotation to where the sample is located. In laboratory centrifuges, this is typically the distance from the rotor center to the sample tube. Convert from centimeters if needed (1 cm = 0.01 m).
Enter Mass
Input the mass (m) of the sample in kilograms (kg). This is the mass being centrifuged. For small samples, convert from grams (1 g = 0.001 kg).
Calculate and Review
Click the "Calculate" button to compute the Relative Centrifugal Force (RCF) in g-force units and the centripetal force in newtons. RCF is commonly used in laboratory settings to describe centrifugation intensity, making it easier to compare results across different centrifuges.
Formula
RCF = (r × ω²) / g
F_centripetal = m × r × ω²
ω = 2π × (RPM / 60)
Where:
• RCF = Relative Centrifugal Force (g-force)
• F_centripetal = Centripetal force (N)
• r = Radius (m)
• ω = Angular velocity (rad/s)
• m = Mass (kg)
• g = Gravitational acceleration (9.81 m/s²)
• RPM = Revolutions per minute
Example 1: Laboratory Centrifuge
A centrifuge runs at 3000 RPM with a sample at 0.1 m radius. The sample mass is 0.01 kg. Calculate RCF and centripetal force.
Given:
• RPM = 3000
• Radius (r) = 0.1 m
• Mass (m) = 0.01 kg
Solution:
ω = 2π × (3000 / 60) = 2π × 50 = 314.16 rad/s
RCF = (0.1 × 314.16²) / 9.81 = 9,870 / 9.81 = 1,006 g
F_centripetal = 0.01 × 0.1 × 314.16² = 0.0987 N
RCF = 1,006 g
Example 2: Ultracentrifuge
An ultracentrifuge runs at 100,000 RPM with a radius of 0.05 m. Calculate RCF for a 0.001 kg sample.
Given:
• RPM = 100,000
• Radius (r) = 0.05 m
• Mass (m) = 0.001 kg
Solution:
ω = 2π × (100,000 / 60) = 10,472 rad/s
RCF = (0.05 × 10,472²) / 9.81 = 5,486,000 / 9.81
RCF = 559,000 g (559,000 × gravity)
Frequently Asked Questions
What is Relative Centrifugal Force (RCF)?
RCF, also called g-force, is the force applied to a sample in a centrifuge relative to Earth's gravity. It's expressed as multiples of g (standard gravity). For example, 1000 g means the sample experiences 1000 times the force of Earth's gravity. RCF is commonly used in laboratories because it's independent of the centrifuge model - you can replicate the same RCF on different machines.
Why use RCF instead of just RPM?
RPM alone doesn't tell you the force on your sample - that depends on the radius. Two centrifuges running at the same RPM but with different rotor sizes will produce different forces. RCF accounts for both speed and radius, giving you a consistent measure of separation force that can be replicated across different equipment.
How do I convert RPM to RCF?
RCF = (r × ω²) / g, where ω = 2π × (RPM / 60). This calculator does the conversion automatically. Alternatively, you can use the formula: RCF = 1.118 × 10⁻⁵ × r × RPM², where r is in centimeters and RPM is in revolutions per minute.
What's a typical RCF value for laboratory centrifuges?
Typical RCF values vary by application: low-speed centrifuges (500-5,000 g) for separating cells, medium-speed (5,000-20,000 g) for separating organelles, high-speed (20,000-100,000 g) for subcellular particles, and ultracentrifuges (100,000-1,000,000+ g) for separating molecules and macromolecules.
How does radius affect RCF?
RCF is directly proportional to radius - doubling the radius doubles the RCF at the same RPM. This is why samples placed further from the center experience higher forces. In a fixed-angle rotor, samples at the bottom of the tube experience higher RCF than those at the top.
Where are centrifuges used in real-world applications?
Centrifuges are used extensively in: medical laboratories (separating blood components, isolating cells), research laboratories (separating proteins, DNA, RNA), industrial applications (separating cream from milk, clarifying juices), wastewater treatment (separating solids), and in manufacturing (separating materials by density).
About Centrifuge Calculator
The centrifuge calculator computes centripetal force and relative centrifugal force (RCF) in g-force units for centrifuges. RCF is a crucial parameter in laboratory work, as it standardizes centrifugation conditions across different equipment.
This calculator is essential for laboratory technicians, researchers, and anyone working with centrifuges. It helps you determine the appropriate settings for separating samples, ensuring consistent results regardless of the centrifuge model used. RCF values are commonly specified in scientific protocols, making this calculator invaluable for following standardized procedures.