The average distance from the sun to the planet Mercury is about 58,000,000 km. The diameter of a human hair is about 0.0025 cm.

Question

What is the diameter of a human hair written in scientific notation?

Answer 1

To express the diameter of a human hair, which is 0.0025 cm, in scientific notation, follow these steps:

1. Identify the significant figures of the number. The significant figure in 0.0025 is 2.5.
2. Count how many decimal places you move the decimal point to the right to get from 0.0025 to 2.5. You move it 3 places to the right.
3. Since you are moving the decimal point to the right, you will subtract 3 from the exponent of 10.

So, 0.0025 can be written in scientific notation as:

\[ 2.5 \times 10^{-3} , \text{cm} \]

Therefore, the diameter of a human hair in scientific notation is \( 2.5 \times 10^{-3} , \text{cm} \).