Question

Answer the following questions.

(a) Why do knives and blades have sharp edges?

(b) Why are ski-boards that are used to glide over ice long and broad?

(c) Why does ink not spill out of an ink dropper?

(d) Why does a plastic bottle full of steam get pressed in if placed in a refrigerator?

Answer 1

(a) _{We know that pressure is inversely proportional to the area.}

_i.e.,

_{This concept is used in cutting anything with knives and blades. The edge of knives and blades is sharpened to reduce the area and as the area is reduced, we need to apply a small force on knives and blades for cutting.}

(b) _{We know that pressure is inversely proportional to the area.}

_i.e.,

_{As the ski−board is long and broad, its area is large and the pressure exerted on it by weight is less. Therefore, the ski-board does not sink in the snow. Hence, ski−boards used to glide over snow are long and broad.}

(c) Ink does not spill out of an ink dropper because the pressure difference between the atmosphere and inside the ink dropper is zero that means pressure inside the ink dropper is equal to the atmospheric pressure.