Explanation:
It is given that,
The North American and European plates of the Earth’s crust are drifting apart with a relative speed of about, v = 25 mm/ yr
We know that, [tex]1\ mm/yr=3.171\times 10^{-11}\ m/s[/tex]
[tex]v=7.927\times 10^{-10}\ m/s[/tex]
Distance between them, [tex]d=2.9\times 10^3\ mi[/tex]
1 mile = 1609.34 meters
[tex]d=2.9\times 10^3\ mi=4667098\ m[/tex]
Let t is the time when the rift between them started to open. Speed is given by distance travelled divided by time taken.
[tex]t=\dfrac{d}{v}[/tex]
[tex]t=\dfrac{4667098\ m}{7.927\times 10^{-10}\ m/s}[/tex]
[tex]t=5.88\times 10^{15}\ s[/tex]
Since, [tex]1\ s=3.17\times 10^{-8}\ yr[/tex]
So, [tex]t=18.63\times 10^7\ years[/tex]
or
t = 1.86 million years
Hence, this is the required solution.
