Tectonic plates are large segments of the Earth's crust that move slowly. Suppose that one such plate has an average speed of 7.5 cm/year.
a)What distance does it move in 1 s at this speed?
b)What is its speed in kilometers per million years?
To find the distance moved by the tectonic plate in 1 second, we need to convert the speed from cm/year to cm/second.
a) To convert cm/year to cm/second, we divide the speed by the number of seconds in a year.
1 year has 365 days, and each day has 24 hours, and each hour has 60 minutes, and each minute has 60 seconds.
So, there are 365 x 24 x 60 x 60 = 31,536,000 seconds in a year.
Therefore, the speed in cm/second is:
7.5 cm/year ÷ 31,536,000 seconds/year ≈ 0.0000002379 cm/second
Now, to find the distance moved in 1 second, we multiply the speed in cm/second by 1 second:
0.0000002379 cm/second x 1 second = 0.0000002379 cm
So, the tectonic plate moves approximately 0.0000002379 cm in 1 second at this speed.
b) To convert the speed from cm/year to kilometers per million years, we need to do two conversions:
First, convert cm/year to km/year. There are 100,000 cm in 1 km, so:
7.5 cm/year ÷ 100,000 cm/km = 0.000075 km/year.
Next, convert km/year to km/million years. There are 1,000,000 years in 1 million years, so:
0.000075 km/year × 1,000,000 years/million years = 75 km/million years.
Therefore, the tectonic plate moves at a speed of approximately 75 km per million years.