Question

After combing your hair l = 11 cm long on a dry day, some of your hair stands up, forced away from your head by electrostatic repulsion. Using the average linear mass density of hair, which is 65 ��g/cm, estimate the mass m of one of your hairs?

Answer 1

To estimate the mass of a hair 11 cm in length, multiply the hair's linear mass density (65 µg/cm) by the hair's length, resulting in a mass of 715 µg, or 0.715 mg, which is a very small mass.

Step-by-step explanation:

To estimate the mass m of one of your hairs that is 11 cm long, you can use the linear mass density given. The average linear mass density of hair is 65 µg/cm (µg is micrograms). The mass of the hair can be calculated by multiplying the linear mass density by the length of the hair.

The calculation would look like this:

m = density × length = 65 µg/cm × 11 cm

Using this formula, the mass m is:

m = 715 µg

This translates to 0.715 mg (milligrams), emphasizing that this amount of mass corresponds to that of a tiny length of hair that is shorter than it is wide, being a fraction of a gram.