When an object is placed in a fluid, it experiences a buoyant force that opposes its weight. This buoyant force is equal to the weight of the fluid displaced by the object. If the object's density is less than that of the fluid, it will float. However, whether the object will leap out of the water or not depends on several additional factors.

1. Density and Size:

- For a sphere to leap out of the water, its density must be significantly lower than that of the water. The larger the difference in density, the greater the buoyant force acting on the sphere.

- The size of the sphere also plays a role. A smaller sphere has a smaller volume and displaces less water, resulting in a weaker buoyant force compared to a larger sphere of the same density.

2. Fluid Properties:

- The viscosity and surface tension of the fluid can affect the behavior of the sphere. Viscosity is the resistance of a fluid to flow, and surface tension is the tendency of a fluid's surface to contract and minimize its area.

- Higher viscosity and surface tension can hinder the sphere's ability to accelerate upward, potentially preventing it from leaping out of the water.

3. Initial Conditions:

- The initial conditions, such as the sphere's initial velocity and position when released, can also influence its trajectory. A sphere released with a higher initial velocity or closer to the surface has a better chance of leaping out of the water before the buoyant force becomes dominant.

4. External Forces:

- External forces, such as wind or currents, can further affect the sphere's behavior. These forces can alter the sphere's trajectory or provide additional momentum that might help it overcome the resistance from the fluid.

In summary, while low density is a necessary condition for an object to float, whether a buoyant sphere will leap out of the water or not depends on a combination of factors, including the sphere's density, size, fluid properties, initial conditions, and any external forces present.