A diver is 20 m below the surface of a lake. If the density of water is 1000 kg/m3, calculate the pressure due to the water alone at this depth. (g = 10 m/s2)

• Capillary action, which is the ability of a liquid to flow in narrow spaces against the force of gravity, is primarily caused by surface tension and adhesive forces between the liquid and the tube walls. Surface tension creates a net upward force on the liquid column.

The final answer is $\boxed{\text{B. Surface tension}}$.

• Terminal velocity is achieved when the net force acting on a falling object becomes zero. At this point, the downward force of gravity (weight) is balanced by the upward forces of upthrust and viscous drag. Since the net force is zero, the acceleration of the object is also zero, and it continues to fall at a constant velocity.

The final answer is $\boxed{\text{C. The net force on the sphere is zero}}$.

• Surface tension is the property of the surface of a liquid that allows it to resist an external force due to the cohesive nature of its molecules. This property causes liquids to minimize their surface area. For a soap bubble, this minimization of surface area results in its characteristic spherical shape.

The final answer is $\boxed{\text{C. The spherical shape of a soap bubble}}$.