A wooden ball of volume $1.0\ \text{litre}$ and density $600\ \text{kg/m}^3$ is tied by a light string to the bottom of an open tank of water, so that it is held fully under water, as shown in the figure (drawn at rest). The tank is deep enough for the ball to stay under water throughout. The tank moves along a straight, level road with a steady acceleration of $7.5\ \text{m/s}^2$, and the water has settled. Take $g = 10\ \text{m/s}^2$ and the density of water as $1000\ \text{kg/m}^3$. Which of the following statements are correct?

Fig. 1: An open tank of water on a level road. A wooden ball is held fully under water by a string tied to the bottom of the tank. The tank is drawn at rest, with a flat water surface and the string vertical. An arrow shows the acceleration the tank will have, to the right.