Physical

RPM ⇄ RCF: practice problems

Convert between rpm and rcf for this rotor. Every answer here is computed by the same tested calculator the rest of the site uses, so a solution can never drift away from the maths.

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Problem 1 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Speed (rpm): 20000
  • Rotor radius (cm): 11
Show the answer and the working

At r = 11 cm, that is 49192 ×g.

  1. Formula: RCF = 1.118 × 10⁻⁵ · r · rpm²
  2. Substitute: RCF = 1.118 × 10⁻⁵ · 11 · 20000² = 49192 ×g

Open this in the calculator to change the numbers.

Problem 2 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Convert: ×g → rpm
  • Force (×g): 25000
  • Rotor radius (cm): 8
Show the answer and the working

At r = 8 cm, that is 16720 rpm.

  1. Rearrange: rpm = √( RCF / (1.118 × 10⁻⁵ · r) )
  2. Substitute: rpm = √( 25000 / (1.118 × 10⁻⁵ · 8) ) = 16720 rpm

Open this in the calculator to change the numbers.

Problem 3 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Speed (rpm): 75000
  • Rotor radius (cm): 10.5
Show the answer and the working

At r = 10.5 cm, that is 660300 ×g.

  1. Formula: RCF = 1.118 × 10⁻⁵ · r · rpm²
  2. Substitute: RCF = 1.118 × 10⁻⁵ · 10.5 · 75000² = 660318.75 ×g

Open this in the calculator to change the numbers.

Problem 4 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Convert: ×g → rpm
  • Force (×g): 10000
  • Rotor radius (cm): 8
Show the answer and the working

At r = 8 cm, that is 10570 rpm.

  1. Rearrange: rpm = √( RCF / (1.118 × 10⁻⁵ · r) )
  2. Substitute: rpm = √( 10000 / (1.118 × 10⁻⁵ · 8) ) = 10570 rpm

Open this in the calculator to change the numbers.

Problem 5 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Speed (rpm): 50000
  • Rotor radius (cm): 12
Show the answer and the working

At r = 12 cm, that is 335400 ×g.

  1. Formula: RCF = 1.118 × 10⁻⁵ · r · rpm²
  2. Substitute: RCF = 1.118 × 10⁻⁵ · 12 · 50000² = 335400 ×g

Open this in the calculator to change the numbers.

Problem 6 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Convert: ×g → rpm
  • Force (×g): 10000
  • Rotor radius (cm): 7
Show the answer and the working

At r = 7 cm, that is 11300 rpm.

  1. Rearrange: rpm = √( RCF / (1.118 × 10⁻⁵ · r) )
  2. Substitute: rpm = √( 10000 / (1.118 × 10⁻⁵ · 7) ) = 11300 rpm

Open this in the calculator to change the numbers.

Problem 7 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Speed (rpm): 15000
  • Rotor radius (cm): 8
Show the answer and the working

At r = 8 cm, that is 20124 ×g.

  1. Formula: RCF = 1.118 × 10⁻⁵ · r · rpm²
  2. Substitute: RCF = 1.118 × 10⁻⁵ · 8 · 15000² = 20124 ×g

Open this in the calculator to change the numbers.

Problem 8 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Speed (rpm): 15000
  • Rotor radius (cm): 13
Show the answer and the working

At r = 13 cm, that is 32700 ×g.

  1. Formula: RCF = 1.118 × 10⁻⁵ · r · rpm²
  2. Substitute: RCF = 1.118 × 10⁻⁵ · 13 · 15000² = 32701.5 ×g

Open this in the calculator to change the numbers.

Problem 9 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Convert: ×g → rpm
  • Force (×g): 10000
  • Rotor radius (cm): 7.5
Show the answer and the working

At r = 7.5 cm, that is 10920 rpm.

  1. Rearrange: rpm = √( RCF / (1.118 × 10⁻⁵ · r) )
  2. Substitute: rpm = √( 10000 / (1.118 × 10⁻⁵ · 7.5) ) = 10920 rpm

Open this in the calculator to change the numbers.

Problem 10 RPM ⇄ RCF

Convert between rpm and rcf for this rotor.

  • Speed (rpm): 25000
  • Rotor radius (cm): 13
Show the answer and the working

At r = 13 cm, that is 90840 ×g.

  1. Formula: RCF = 1.118 × 10⁻⁵ · r · rpm²
  2. Substitute: RCF = 1.118 × 10⁻⁵ · 13 · 25000² = 90837.5 ×g

Open this in the calculator to change the numbers.

More physical practice

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