Final answer:
With no work done against friction on a block moving from one point to another, the block's kinetic energy remains unchanged according to the work-energy principle, provided no other forces do work on the block.
Step-by-step explanation:
If a 10 kg block moves from position a to position b without any work done against friction, then the block's kinetic energy remains unchanged. In physics, the work-energy theorem states that the work done on an object is equal to the change in its kinetic energy. Since no work is being done against friction, the block is not losing energy to frictional forces. Therefore, provided that there are no other forces doing work on the block (like gravity doing negative work if the block is moving uphill), its speed would remain constant, meaning that its kinetic energy would stay the same. This assumes no other sources of work acting on the block and no energy transformations. Therefore, the correct statement would be that the kinetic energy neither increases nor decreases.