A 66-N ⋅ m torque acts on a wheel with a moment of inertia 175 kg ⋅ m2. If the wheel starts from rest, how long will it take the wheel to make one revolution?

t = 5.77 s

Explanation:

This exercise will use Newton's second law for rotational motion

            τ = I α

             α = τ / I

             α = 66/175

             α = 0.3771   rad/s²

now we can use the rotational kinematics relations, remember that all angles must be in radians

            θ = 1 rev = 2π radians

            θ = w₀ t + ½ α t²

as the wheel starts from rest w₀ = 0

             t = √ (2θ/α)

let's calculate

             t = √ (2 2π / 0.3771)

             t = 5.77 s

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s