# Another Question

• October 13th, 2009, 04:29 AM
Snoogy
Another Question
if you have read any of my previous posts you will probably know that I am not as bright as I would like to be, but here goes. :oops:

I live in the UK, I went to vist a friend in Australia, the flight took 23 hours. I know that Australia is half way round the World. It takes the Earth 12 hours to complete half a rotation. Surely if my plane travelled directly up, hovvered for 12 hours then came back down, it would end up near Australia saving time! would that work?

Also if it travelled towards the rotation of the Earth would it be reach the destination faster than if it travvelled with the rotation?
• October 13th, 2009, 06:31 AM
Harold14370
Hovering over a fixed point relative to the center of the earth, you can only go east-west. To get to Australia, you need to go south.

Aside from that, suppose you just want to travel east-west. The circumference of the earth at the equator is 24,901 miles (40,075 km). At the latitude of 51 degrees it is 15671 miles (25220 km) around the earth following the latitude line. The earth rotates once in 24 hour, so at that latitude, the surface traveling 653 mph (1051 kmph).

Since you are traveling at the speed of the earth's surface, you would need to get stopped in order to hover over the same point. That means accelerating to 1051 kilometers per hour relative to the earth's surface. The atmosphere will be traveling at the same speed as the earth's surface, so you will have to battle a 1051 kilometer per hour head wind to hover over a fixed point, ignoring local wind speed.
• October 13th, 2009, 06:41 AM
Snoogy
what if you leave the earths atmosphere?
• October 13th, 2009, 06:14 PM
Harold14370
The surface of the earth is moving west to east, so if you launch something straight up, it will come down west of where it was launched. However, as I said before, to launch it straight up, you have to subtract the 653 mph eastward velocity component it has due to the earth's rotation. That means, from your vantage point, it has to be launched 653 mph west, not straight up. To you, it would look pretty much the same launching it eastward or westward, except maybe some minor deflection due to the Coriolis effect. There is no free ride because of the earth's rotation.