The impulse needed to bring the brick to rest is equal to the change in momentum of the brick. The initial momentum of the brick is:

$$p_i = mv_i = (8 kg)(0 m/s) = 0 kg m/s$$

The final momentum of the brick is:

$$p_f = mv_f = (8 kg)(-9.8 m/s) = -78.4 kg m/s$$

Therefore, the impulse needed to bring the brick to rest is:

$$J = p_f - p_i = -78.4 kg m/s - 0 kg m/s = -78.4 kg m/s$$

The negative sign indicates that the impulse must be in the opposite direction of the brick's motion.