Does Earth's rotation change at a constant rate? Follow-up to
Is Earth's orbit altered by recoil from take-off/launch/recovery of aero/space vehicles?
How much meteoric/space dust does the moon accumulate daily?
Is the length of the day increasing?
I understand the addition of mass probably slows Earth's rotation. As Earth gains mass does it's gravity attract space/meteoric dust in an increasing quantity? Ergo, Does Earth's rotation change at a constant, or accelerating rate?
 A: The major effects - the tidal friction with the moon slow the Earth at a constant predictable rate
On top of this there are many effects that change the mass distribution and so the moment of inertia of the Earth. Earthquakes have the greatest effect but every landslide, flood and avalanche have tiny random effects 
A: The rate of accretion of dust and other particles on Earth is not constant. Just think of a large meteor burning up in minutes in the atmosphere: that could add tens or hundreds of kilograms of material in just a few minutes, orders of magnitude more than the average amount of dust collected for that period.
As the rate of accretion of dust and other particles on Earth is not constant, neither is the rotational acceleration / deceleration of the Earth's spin.
A: The forces which effect the angular velocity of the earth are against the direction of rotation. The only significant force I can think of is the tidal force, perhaps air resistance from the atmosphere on mountains etc...?
A rocket may produce a force, but it's going to be absolutely negligible absolutely negligible. Think about moving the mass of a rocket and the mass of all the water on the planet. 
The length of the day is increasing if the earths rotation is slowing down.
A: Tidal friction with the moon is the main cause and since the moon is slowly moving away from the earth, tidal friction is on the decline and the rate will decrease.
