So here we have an example problem that says, if Earth rotated exactly as it does, but in the opposite direction, which of the following would likely occur? And we've got these four potential answer options down below. Now, of course, recall from our previous lesson videos that Earth rotates or spins on its tilted axis towards the east. The rotation of Earth is ultimately what determines day and night, and the speed of the rotation of Earth is what determines the length of the day. It takes about 24 hours for Earth to make one complete rotation, which is why we call a day 24 hours.
Now, if Earth rotated exactly as it does, but only in the opposite direction, then we could assume that the speed of the rotation would be the same, and then the length of the day would not be affected. That means we can eliminate answer options c and d, which both indicate that the length of the day would be affected. Option c says the days would become shorter, and option d says the days would become longer. But, again, if the rotation speed is not changed, then the length of the day would be unchanged. So now, we are between either option a or option b, which both indicate the direction of the prevailing winds at the equator.
Option a says that they would blow from west to east, meaning it would be a westerly since it's blowing from the west. Then, option b says that it would blow from east to west, meaning it would be an easterly since it's blowing from the east. Now, recall from our previous lesson videos that the Coriolis effect is going to curve or deflect the paths of prevailing winds. And recall that the winds blowing towards the equator will be curved or deflected westward. What helps us remember that is that the equator phonetically sounds like it has a 'w' in it, so we know that it's going to be deflected westward.
And so notice that westward means from the east toward the west, and so that's going to be option b. Under normal circumstances, when Earth is rotating in its normal direction towards the east, option b indicates how we would expect the prevailing winds to be deflected. But in this scenario, we know that the rotation is going to be opposite, so it's not going to be the normal situation but instead the opposite effect, which means that option a is going to be the correct answer for this problem. The prevailing winds at the equator would blow from west to east, meaning it would be a westerly, and that means the prevailing winds would blow eastward. Again, this is a hypothetical situation.
In reality, the winds blow westward at the equator. But a very interesting example problem, a is the correct answer, and I'll see you all in our next video.