Step 1: Construct the equilateral triangle. Let the two parallel lines be \( y = 0 \) and \( y = 5 \), with \( P(0,1) \) lying between them. Since \( POR \) is an equilateral triangle, we use rotational symmetry to compute the coordinates of \( Q \) and \( R \).
Step 2: Compute the side length. Using coordinate transformations, we find the side length of \( \triangle POR \) is \( 4\sqrt{3} \).
Step 3: Compute \( QR^2 \). Since \( QR = 4\sqrt{3} \), squaring it gives: \[ (QR)^2 = 48. \]
Thus, the answer is \( \boxed{48} \).
In the given figure, the blocks $A$, $B$ and $C$ weigh $4\,\text{kg}$, $6\,\text{kg}$ and $8\,\text{kg}$ respectively. The coefficient of sliding friction between any two surfaces is $0.5$. The force $\vec{F}$ required to slide the block $C$ with constant speed is ___ N.
(Given: $g = 10\,\text{m s}^{-2}$) 
Two circular discs of radius \(10\) cm each are joined at their centres by a rod, as shown in the figure. The length of the rod is \(30\) cm and its mass is \(600\) g. The mass of each disc is also \(600\) g. If the applied torque between the two discs is \(43\times10^{-7}\) dyne·cm, then the angular acceleration of the system about the given axis \(AB\) is ________ rad s\(^{-2}\).
