The homemade pen cap sinker
Make a pen cap sinker to demonstrate Pascal’s law Fill the plastic bottle with water. Attach a piece of clay to the arm of a plastic pen cap. Put the cap in the bottle so that it floats. Put the lid on the bottle and tighten so that it does not leak any air. Squeeze the sides of the bottle. What do you think causes the pen cap to sink when you squeeze the sides of the bottle? By squeezing the bottle, you increase the pressure inside, thus forcing more water up into the pen cap. The added water in the cap increases its weight and causes the cap to sink. A submarine works along these same principles. If the average density of the submarine is less than that of the water