Mistake Master
Mistake Master · AP Physics C · Unit 5 · Topic 5.6 · Step-Through Animation
Torque Sets the Spin-Up
You'll learnthat the same torque spins up a wheel differently when its rotational inertia changes.
The same tangential force spins one wheel up fast and another slowly — because where the mass sits decides how it answers. Net torque plays force, rotational inertia plays mass, angular acceleration answers: τ = Iα, with τ = dL/dt waiting underneath for when the inertia itself changes.
ROTATION LAB
Before you start
What you're looking at
Two wheels of equal mass, each pulled at the rim with F = 12 N at r = 0.5 m, giving the same net torque τ = 6 N·m.
The question
Given the same torque, which wheel spins up faster?
Watch for
The ω-t chart. The wheels share mass but not its distribution, and one leaps ahead of the other.
What the symbols mean
τ = net torque plays force, I = rotational inertia plays mass, α = angular acceleration answers: τ = Iα.
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