Let $x=\pi R\left(\frac{P^2-Q^2}{2}\right)$, where $P, Q$ and $R$ are lengths. The physical quantity $x$ is

Let force $$F=A \sin (C t)+B \cos (D x)$$, where $$x$$ and $$t$$ are displacement and time, respectively. The dimensions of $$\frac{C}{D}$$ are same as dimensions of

$\left[\mathrm{L}^2 \mathrm{M}^1 \mathrm{~T}^{-2}\right]$ are the dimensions of

The force ' $F$ ' acting on a body of density ' $d$ ' are related by the relation $F=\frac{y}{\sqrt{d}}$. The dimensions of ' $y$ ' are