Step-by-step explanation:
The rate at which the Atlantic Ocean is opening up, 2 cm per year, is known as the spreading rate. This rate is not constant over time, but it has varied in the past. However, assuming a constant spreading rate of 2 cm per year, we can estimate how long it would have taken for the Atlantic Ocean to form.
The Atlantic Ocean began to form during the Jurassic Period, around 200 million years ago. At that time, the supercontinent of Pangaea began to break apart, and the Atlantic Ocean started to open up. To calculate how long it would have taken for the Atlantic Ocean to reach its current size, we need to know the approximate size of the ocean and its spreading rate during that time.
The current size of the Atlantic Ocean is about 106,000,000 square kilometers. If we assume that the spreading rate has been constant over the past 200 million years, then the Atlantic Ocean would have opened up by a distance of:
Distance = Rate x Time
Distance = 2 cm/year x (200,000,000 years)
Distance = 4,000,000 cm
To convert this distance into kilometers, we divide by 100,000:
Distance = 4,000,000 cm / 100,000
Distance = 40 km
So, if the spreading rate has been constant over the past 200 million years, the Atlantic Ocean would have opened up by 40 km. Since the current size of the Atlantic Ocean is about 106,000,000 square kilometers, it would have taken:
Time = Distance / Rate
Time = 40 km / 2 cm/year
Time = 2,000,000 years
Therefore, if the spreading rate has been constant over the past 200 million years, it would have taken approximately 2 million years for the Atlantic Ocean to reach its current size. However, it is important to note that the spreading rate has not been constant over time and has varied.