A wheel rotating about a fixed axis has a constant angular acceleration of 4.0 rad/s2. In a 4.0-s interval the wheel turns through an angle of 80 radians. Assuming the wheel started from rest, how long had it been in motion at the start of the 4.0-s interval?
A)2.5 s
B)4.0 s
C)3.5 s
D)3.0 s
E)4.5 s

Question

Quizplus · Accepted Answer

Using the equation θ = ω₀t + 0.5αt², where θ = 80 rad, ω₀ = 0, α = 4.0 rad/s², and t = 4 s, we find the initial time t₀ by solving 80 = 0.5 * 4 * (t₀ + 4)² - 0.5 * 4 * t₀², which gives t₀ = 3.0 s.

A Wheel Rotating About a Fixed Axis Has a Constant