Here's why:

* Uniformly accelerated motion means an object changes its velocity at a constant rate. This means the object gains or loses the same amount of speed in every equal time interval.

* Acceleration is the rate of change of velocity.

* If acceleration is constant, it means the rate of change of velocity is constant, resulting in uniform acceleration.

In simpler terms: If you want something to speed up or slow down smoothly and predictably, the force causing that change needs to stay the same.