A block on a smooth surface remains in translational equilibrium while two forces act on it:
1. An external force Fext=6i^−2j^+4k^N.
2. The reaction force FRB exerted by a rigid rod in contact with the block.
The block exerts an action force on the rod given by FBR=6i^−2j^+ak^N. Calculate the value of a.
a) −4
b) 0
c) 4
d) 2