Final answer:
Tectonic plates move slowly, and one such plate has an average speed of 4.0 cm/year. In 1 second, it moves about 1.27 × 10^-7 cm. Its speed in kilometers per million years is about 4.0 × 10^-11 km.
Step-by-step explanation:
Tectonic plates move slowly, and one such plate has an average speed of 4.0 cm/year. To find the distance it moves in 1 second at this speed, we need to convert the yearly speed to seconds. There are 31536000 seconds in a year, so the plate's speed in seconds is 4.0 cm/year divided by 31536000 s/year, which comes out to about 1.27 × 10-^7 cm/s. To find the distance it moves in 1 second, we multiply the speed by the time: 1.27 × 10-^7 cm/s × 1 s = 1.27 × 10-^7 cm.
To find its speed in kilometers per million years, we need to convert the yearly speed to million years. There are 1000000 years in a million years, so the plate's speed in million years is 4.0 cm/year divided by 1000000 years/million years, which comes out to 4.0 × 10-^6 cm/million years. To convert this to kilometers per million years, we divide by 100000 cm/km: 4.0 × 10-^6 cm/million years ÷ 100000 cm/km = 4.0 × 10-^11 km/million years.