The cross-section of a built-up wooden beam as shown in the figure (not drawn to scale) is subjected to a vertical shear force of $8 \: kN$. The beam is symmetrical about the neural axis (N.A.) shown, and the moment of inertia about N.A. is $1.5 \times 10^9 \: mm^4$. Considering that the nails at the location P are spaced longitudinally (along the length of the beam) at $60 \: mm$, each of the nails at P will be subjected to the shear force of

1. $60 \: N$
2. $120 \: N$
3. $240 \: N$
4. $480 \: N$