What represents displacement at the nth second in motion equations?

Displacement at the nth second in uniformly accelerated motion can be defined using the formula that calculates the distance traveled during the nth second. This is represented by the formula involving the initial velocity (u), acceleration (a), and the previous displacement.

The correct equation shows that the displacement at the nth second can be derived from the initial conditions and incorporates the effect of acceleration by using the previous second's displacement. This formula indicates that the displacement in the nth second is greater than or lesser than the previous second depending on the value of acceleration. The dependency on the subtraction of the displacement of the (n-1)th second illustrates how each second's displacement builds on the prior one, and incorporating acceleration in the equation reflects how the object's velocity is changing.

Other options either represent overall displacement over time rather than focusing specifically on the displacement during the nth second or involve different formulations of motion equations that do not specifically isolate the displacement at a particular second in a straightforward manner. Thus, the structure and variables in the first equation align directly with the concept of calculating displacement in a given second under constant acceleration, making it the correct choice for this context.