Question

Hair grows at an average speed of 3x10^-9 m/s. how long does it take to get to 10cm? note: 1 yr = 3.156 × 10^7 s.

Answer 1

Given that the growth speed of hair is 3 x 10^-9 m/s.

We have to determine how long would it take to get to 10 cm.

It is known that t = d/s.

Here, d = 10 cm = 0.1 m and s = 3 x 10^-9 m/s. So,

`\begin{gathered} t=(0.1)/(3*10^(-9)) \\ t=(0.1*10^9)/(3) \\ t=(10)/(3)*10^8 \\ t=3.33*10^8\text{ seconds} \end{gathered}`

We know that 1 yr = 3.156 × 10^7 s. So, the time taken (in years) is:

`(3.33*10^8)/(3.156*10^7)=1.055*10=10.55\text{ years}`

Thus, it will take 10.55 years to grow the hairs to 10 cm.