Chapter 27, Problem 1TS

To determine

The time to reach the mid-Atlantic ocean to its present width.

Answer to Problem 1TS

The Atlantic Ocean has taken $2\times {10}^8\text{yr}$ to reach its present width.

Explanation of Solution

Given info: The width of the mid-Atlantic ocean is $5000\text{km}$ and the rate of Atlantic ocean spread is $2.5\text{cm}/\text{yr}$.

Write the expression for the time in which ocean reach to its width.

$n=\frac{d}{r}$

Here,

$n$ is the number of years

$d$ is the width of the Atlantic ocean

$r$ rate of spread of the Atlantic ocean

Substitute $5000\text{km}$ for $d$ and $2.5\text{cm}/\text{yr}$ for $r$ in the above expression to find $n$.

$\begin{array}{c}n=\frac{5000\text{km}}{\left(2.5\text{cm}/\text{yr}\times \frac{1\text{km}/\text{yr}}{{10}^5\text{cm}/\text{yr}}\right)}\\ =2\times {10}^8\text{yr}\end{array}$

Conclusion:

Therefore, the Atlantic Ocean has taken $2\times {10}^8\text{yr}$ to reach its present width.