Question

Question:A piece of unpainted porous wood barely floats in an open container partly filled with water. The container is then sealed and pressurized above atmospheric pressure. What happens to the wood? (a) It rises in the water. (b) It sinks lower in the water. (c) It remains at the same level.

Short answer

Block will float on the surface of water, and remains at the same level. Hence option (b) is the correct answer.

Step-by-step solution

Step 1: Archimedes’ principle

When an object is partially or fully submerged in a fluid, the fluid exerts on the object an upward force called the buoyant force. According to Archimedes’s principle, the magnitude of the buoyant force is equal to the weight of the fluid displaced by the object:

B =${\rho }_{Fluid}g{V}_{disp}$

Where V_disp the volume of fluid is displaced and $\rho$_Fluidis the density of the fluid.

Find what happens to the wood

AccordingtoArchimedes’s principle, the block will float on the water because, when pressure increases, volume decreases and ultimately density will also decrease.

Hence block will float on the surface of water, and remains at the same level. Hence option (b) is the correct answer.