The Atlantic Ocean between the east coast of the United States and the west coastof Africa is about 6,000 kilometers (km) wide. The age of the oceanic Lithosphere between them is 280,000,000 years old. What is the average rate of seafloor spreading?

The answer is 2.14 cm/yr

Explanation:

To calculating Sea Floor Spreading

The formula to follow is: Rate of Spreading = distance the sea floor moved / length of time

or R = d/t

Generally expressed as cm/yr

1 km = 1000 m

1 m = 100 cm

so 1 km = 100,000 cm or 10^5 cm

To calculate the real distance that the plate has moved over the past 280 million years,

Given that we have 6,000km, Hence: we convert kilometers to centimeters

Therefore 6000km = 600,000, 000 cm = 6 * 10^8 cm

Then, determine the length of time that the plate has been moving

280 million years = 280,000,000 years = 2.8 * 10^8 years

Use the above equation to calculate spreading rate

R = d/t or R = 6 * 10^8 cm / 2.8 * 10^8 years = 2.14 cm/yr