A flat rectangular gate, $2.0\ \text{m}$ wide and $3.0\ \text{m}$ tall, closes a channel. It is hinged along its bottom edge, on the floor of the channel. Water stands on one side of the gate, right up to its top edge, and there is air on the other side. A horizontal strut (a rigid prop) on the air side pushes on the top edge of the gate and holds it upright, as shown in the figure. Take $g = 10\ \text{m/s}^2$ and the density of water as $1000\ \text{kg/m}^3$. Ignore the weight of the gate. What is the force in the strut?

Fig. 1: Side view of a flat vertical gate 3.0 m tall, hinged at its bottom edge on the floor of a channel. Water on the left stands up to the top edge of the gate, and there is air on the right. A horizontal strut on the right, from a fixed post, pushes on the top edge of the gate.