A block of metal weighing \( 2 \, \text{kg} \) is resting on a frictionless plane (as shown in figure). It is struck by a jet releasing water at a rate of \( 1 \, \text{kg s}^{-1} \) and at a speed of \( 10 \, \text{m s}^{-1} \). Then, the initial acceleration of the block, in \( \text{m s}^{-2} \), will be:
