In a laboratory experiment, various torques are applied to a rotor and the angular acceleration is measured. The results are plotted on the accompanying graph. From the graph, the moment of inertia of the rotor is A) 0.010 kg · m² B) 0.011 kg · m² C) 0.0125 kg · m² D) 0.0138 kg · m² E) 0.0225 kg · m²

Question

Quizplus · Accepted Answer

The moment of inertia (I) can be determined from the slope of the linear portion of the graph where torque (τ) is plotted against angular acceleration (α). 
Using the equation τ = Iα, we have 
I = τ/α

From the graph, the slope of the linear portion is approximately 0.5 N·m/rad/s2. 
Thus, I = τ/α = 0.5 N·m/rad/s2 / 40 rad/s2 = 0.0125 kg·m2.

Therefore, the best choice is C.

In a Laboratory Experiment, Various Torques Are Applied to a Rotor