Nah. I telling about that 24 hours it's agian, humanmade thing. Time is a humanmade thing. But sun shines different amount of time in different places, so it maybe that sun never changes it's speed.
A Day is determined by the positions of the Sun. A Day is the time it takes for the Sun to appear at the same point in the sky again. We divided this up into 24 hours in Babylonian times (they had a base 60 number system

- it is why we have 60 seconds in a minute and 60 minutes in an hour, it is also why we have 360 degrees in a circle).
Now if we use some device (or even multiple devices that use different mechanisms so as to avoid any errors due to the mechanism) to measure the time it takes for a single day (say counting the number of swings of a pendulum), we can then check to make sure that each Day is the same, as if they are the same on the device, then they must be the same.
But, the total time (eg number of swings of the pendulum) is the same regardless of the season, or you position on the Earth.
This means that the Sun must make a circle around the FE every 24 hours (as we break up the swings of the pendulum for convenience sake) regardless of your position or season.
Mathematically the Angular Velocity of the Sun is therefore 360 degrees every 24 hours (15 degrees/hour).
Now using Pi to calculate the Circumference of a circle (2 * Pi * Radius) we can see that if the radius increases the Circumference must also increase. So if the Sun is closer to the North Pole in the Northern Summer, then the circumference of that circle must be smaller than the one for the Southern Summer.
As the Sun must make this trip in the same time, and Speed is Distance divided by Time, then the Sun must be travelling faster in the Southern Summer than the Northern Summer.
Here are the Formulas (as I haven't been given the radius of the Sun in the Northern and Southern Summer times, I'll just have to stick with the formulas until I get them - or if you have them you can easily substitute them into the formulas yourself):
Southern Summer Sun Radius = R
1Northern Summer Sun Radius = R
2Speed of Sun in the Southern Summer: 2 Pi R
1 / 24
Speed of Sun in the Northern Summer: 2 Pi R
2 / 24
The Laws of Conservation of momentum when applied to an rotating system (like the sun in FE) state that the momentum can't just disappear without some outside cause (just as it can't be created from nothing too). This is the Law of Conservation of Angular Momentum, and is used by Ice Skaters when doing a pirouette. If they start with their arms outstretched, then pull them in, they will speed up. And, if they started with their arms in and move them outwards, they will slow down.
But the FE Sun is doign the Exact opposite!

It is speeding up as it goes outwards, and slows down as it moves inwards.
So not only does FET have to account for the change in velocity to cover the same angle in the same time, they also have to account for the apparent violation of the Conservation of Angular Momentum law (which can be proved by ice skaters).