A large tank of water stands on a cart that can roll on smooth level rails. A small hole of area $4.0\ \text{cm}^2$ is opened in one side of the tank, $1.25\ \text{m}$ below the water surface, and water spurts out horizontally, along the rails, as shown in the figure. Take $g = 10\ \text{m/s}^2$ and the density of water as $1000\ \text{kg/m}^3$. What horizontal force is needed to keep the cart at rest just after the hole is opened?

Fig. 1: A large tank of water on a cart with wheels on level rails. A small hole of area 4.0 square cm in the right side of the tank is 1.25 m below the water surface, and a jet of water spurts out horizontally to the right.