Question

how long does it take the earth to completely rotate once on its axis?

Answer 1

It takes the earth 24 hours/ 1 day to completely rotate once on its axis. Which causes night and day by the way the earth is tilting towards the sun.

Answer 2

Planet Earth has just enough gravity to hold its atmosphere around it. Earth has a moon. The moon causes the tides to change, making them rise and fall. Earth orbits the Sun in about 365 days to make an Earth year. It rotates every 24 hours to make an Earth day.