w₀ = initial angular velocity of the car wheel = 0.5 rad/s
w = final angular velocity of the car wheel = 0 rad/s
n = number of revolutions revolved by wheel before coming to rest = 2
θ = angular displacement = 2nπ = 2 x 2 x 3.14 = 12.56 rad
α = angular acceleration of the wheel = ?
using the equation
w² = w₀² + 2 αθ
0² = 0.5² + 2 (12.56) α
α = - 9.95 x 10⁻³ rad/s²