Mass Moment of Inertia Calculator

Your details

Total mass of the object.
kg
Outer radius, or for a rectangular plate the full width.
m
Rod length, or second dimension of a rectangular plate.
m
Add I_cm + m*d^2 to shift the axis from the centroid to a parallel axis at distance d.
Moment of inertia (I)
0.08

Rotational inertia about the selected axis

I (display units)0.0800 kg·m²
I about centroid (I_cm)0.0800 kg·m²
Parallel-axis term (m * d^2)Not applied
Axisany axis through center
Total I0.08

I = 0.0800 kg*m^2

  • The solid sphere has a rotational inertia of 0.0800 kg*m^2 about the selected axis.
  • A solid sphere has one of the lowest shape factors (2/5 = 0.4), meaning it spins up faster than a hoop of the same mass and radius.
  • Moment of inertia governs how much torque is needed to achieve a given angular acceleration: tau = I * alpha.

Next stepTo find the angular acceleration caused by a torque, divide that torque (in N*m or lb*ft) by this moment of inertia.

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