Sometimes, we can't measure the moment of inertia directly. For example if the object is oddly shaped. In such cases, we can use an indirect way to measure the moment of inertia - this is described in the Introduction of the lab book here (we recommend you read/watch this before answering the questions). The general principle is that a falling block causes the disc to rotate, such that at any time gravitational PE lost by block-earth = linear KE gained by block + rotational KE gained by disc If 10 is the moment of inertia of the disc and a) is its angular velocity, which expression allows you to calculate the rotational energy of the disc? Select one: a. 1002/2 V b 10(02 0 10a) d Iorco2 If m is defined to be the mass of the block, then from question 3, we know that gravitational PE lost by block-Earth = linear KE gained by block + rotational KE gained by disc Or, mghi = mui+ - low, Substitute your answers to the previous questions into this equation and rearrange to find Jo. Select the correct answer from the multiple choices given below. Select one: Oa. Io = mgrij - my- Ob. 10 = mgrit 4x O c. In = mgri + mr2 8x Od. In = mgri - mr- Oe. lo = mgrli - my-2