Question

Alexa's hair grows with an average speed of 3.5 × 10–9 m/s. how long does it take her hair to grow 0.30 m? note: 1 yr = 3.156 × 107 s.

Answer 1

we are given

speed  of 3.5 × 10^–9 m/s

Let's assume speed of hair is v

so,

$v=3.5*10^{-9}m/s$

now, we are given

her hair to grow 0.30 m

so,

$d=0.30m$

we have to find time (t)

so, we can use formula

$t=\frac{d}{v}$

we can plug values

and we get

$t=\frac{0.30}{3.5*10^{-9}}$

now, we can simplify it

$t=85714285.71429 s$

now, we know that

$1 yr = 3.156* 10^7 s$

we can find for 1s

$1s=\frac{1}{3.156* 10^7} yr$

$t=85714285.71429*1 s$

we can replace 1s

we get

$t=85714285.71429*\frac{1}{3.156* 10^7} yr$

now, we can simplify it

and we get

$t=2.71592 yrs$..............Answer