Answer:
This can be answered at different levels, and some good ‘deeper’ answers have already been given. Here is one take on it …
All moving objects keep moving as they are, unless some unbalanced force acts on them (Newton’s first law). In the case of any object on earth, sliding along a horizontal surface, there are three main forces acting on it. (1) The weight of the object, trying to pull it down towards the ground. (2) a force from the surface pushing up, exactly matching the weight (so it stays on the surface and doesn’t either rise above it or fall through it), and (3) a ‘sliding friction’ force which acts against the direction of motion of the object.
This frictional force is described in some detail in the answer from Günter Marksteiner. But in outline, the frictional force acts to slow the object down, and depends on the weight of the object and the nature of the object and surface (how ‘slidey’ they are). The heavier the object, the greater the force. The slidier, the surfaces, the less the force.
As friction operates, it causes kinetic energy from the motion of the object as it slows to be converted mostly to heat. This is why brakes on cars and aeroplanes heat up, and why rubbing your hands together vigorously warms them.
As well as friction, there is also air resistance - the drag of moving through the air. But this is usually small in comparison to friction (unless you’re a downhill ski racer perhaps, when streamlining becomes important).
The answer is more interesting than you might expect. The “hard stop” observed is not due to friction, van der Waal coupling (stickiness), nor is it caused by the moving object “running out” of energy. An object’s eventual loss of linear motion, whether the object be rolling or bouncing, is due to the physical property of elasticity. More specifically, the object and the surface it is moving on, each has a finite bulk elastic constant which results in a slight deformation in the shape of both the object and the surface that it is resting against. The question presumes that the instant object i
