Flywheel Energy Calculator
Stored energy, moment of inertia and rim speed of a solid disc flywheel.
Results
Energy
19,276.6
J
Moment of inertia
1.56250
kg·m²
Speed
157.080
rad/s
Speed
39.270
m/s
What this tool does
Energy rises with the square of the speed and with the square of the radius, so making a flywheel wider buys far more than making it heavier. Rim speed is the number that limits the design: spin a disc fast enough and it tears itself apart, which is why guarding matters.
Formula
I = ½ m r² , E = ½ I ω²
Variables
| Symbol | Meaning | Unit |
|---|---|---|
m | Mass | kg |
r | Radius | m |
n | Rotational speed | rpm |
E | Energy | J |
I | Moment of inertia | kg·m² |
W | Speed | rad/s |
V | Speed | m/s |
Worked example
- Mass50 kg
- Radius0.25 m
- Rotational speed1500 rpm
- Energy19,276.6 J
- Moment of inertia1.56250 kg·m²
- Speed157.080 rad/s
- Speed39.270 m/s
Limitations
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.