Question

In order to achieve good curl formation, the hair should circle the rod at least:

A. 1 1/2
B. 2
C. 2 1/2
D. 3

Answer 1

To match the moment of inertia of System A with System B, we calculate the moment of inertia for each system and set them equal. The calculations show that 4 smaller disks are needed in System B to equal the moment of inertia of System A.

Step-by-step explanation:

The original question regarding hair curling does not correlate directly with the reference physics problems provided. However, I can address the physics question, which pertains to the moment of inertia of rotating systems. To find the number of smaller disks needed in System B to equal the moment of inertia of System A, we apply the formula for the moment of inertia of a solid disk, which is I = ½MR², where M is mass and R is radius. System A consists of two larger disks with radius 2R, while System B consists of one larger disk with radius 2R and a number of smaller disks with radius R.

For System A, the moment of inertia is:

I_A = 2(½M(2R)²) = 2M(2R)²

For System B, with 'n' smaller disks, the moment of inertia is:

I_B = ½M(2R)² + n(½MR²)

Equating I_A and I_B and simplifying:

2M(2R)² = ½M(2R)² + n(½MR²)

4M(2R)² = M(2R)² + 2n(MR²)

8 = 1 + 2n

2n = 7

n = 3.5

Since we can't have half a disk, the closest number of whole disks is 4. Therefore, System B needs 4 smaller disks to have the same moment of inertia as System A.