Physics
posted by Steve on .
Take into account the Earth's rotational speed (1 rev/day) and determine the necessary speed, with respect to the Earth, for a rocket to escape if fired from the Earth at the equator in a direction a) eastward; b) westward; c) vertically upward.
The answers are 1.07 x10^4 m/s, 1.17 x10^4 m/s and 1.12 x10^4 m/s. I got c but I don't understand what to do for a and b.

The sun rises in the East.
Therefore even if stationary, you are already moving East with the surface of the earth. That Eastward speed is 2 pi*earth radius / (24 hr*3600 seconds/hr)
If you launch Eastward, your total speed is the speed relative to earth PLUS the speed of that point on the earth. If you launch westward your total speed is the speed relative to earth MINUS the speed of that point on the earth. Therefore you will need more rocket push to reach escape speed if you launch westward.