Hence, the pressure of water in a dam is much greater at the bottom of the dam than at the top.Ģ. The pressure at a point in a liquid is proportional to the height of the liquid column above it. Why does it happen? The wall of a dam is broad at its base.ġ. Presently we are considering only the force acting on an area in a direction perpendicular to it.The force exerted perpendicularly on a unit area is called ‘pressure’.Why does it happen? Fruits can easily he cut with a sharp knife. Therefore, a ship dips to a larger depth in freshwater as compared to marine water. Hence, the buoyant force on a body in freshwater is less than that in marine water. The density of freshwater is less than that of marine water. The buoyant force acting on a body is proportional to the density of the fluid in which the body is immersed. Why does it happen? A ship dips to a larger depth in freshwater as compared to marine water. Hence, we don’t feel the atmospheric pressure. Their pressure balances the pressure due to the atmosphere. The cavities in our body are filled with air, and arteries and veins are filled with blood. This is the pressure that we carry on our heads. The air pressure at the sea level is about 101 × 10 3 Pa. How much pressure do we carry on our heads? Why don’t we feel it? Also, the pressure increases as the depth of the liquid increases. What is understood from this? At any one level, the liquid pressure is the same. The jet from the lowest hole falls farthest from the bottle.Īlso, jets coming out from the two holes at the same level fall at the same distance from the bottle. The water jet emerging from the hole at the top will fall closest to the bottle. A shown in the figure, water jets will be seen emerging and projecting out. Fill water in the bottle up to full height. Pierce it with a thick needle (or with a hot nail) at the points 1, 2, 3 as shown in the Fig. What is observed? The pressure of water acts on the side of the bottle as well. Warm up one end of the glass tube and gently push it into the bottle at about balloon inflates. Take a 10 cm long piece of a glass tube on which a rubber balloon can be fitted. Hence, the pressure decreases and the tyres do not burst. Load carrying heavy vehicles have large number of wheels so that the load (weight, force) is distributed over large surface area of the wheels in contact with the road. The greater the surface area, the less is the pressure produced. The pressure produced by a given force depends on the area of the surface on which the force acts. Why do the load carrying heavy vehicles have large number of wheels? Will it sink or come to the surface of water? Answer the following questions in brief.Ī plastic cube is released in water. The air pressure on our body is equal to the atmospheric pressure.įor a given object, the buoyant force in liquids of different ………… is ………….įor a given object, the buoyant force in liquids of different density is the same.ģ. The air pressure on our body is equal to the …………. Maharashtra State Board Class 8 Science Solutions Chapter 3 Force and PressureĬlass 8 Science Chapter 3 Force and Pressure Textbook Questions and Answers Surface tension and viscosity both have been synergized, and an Ameta-Singh-Interaction-Analysis-Model (ASIAM) for physicochemical properties has been proposed to distinguish interaction pattern and a role of secondary cohesivity in developing dominance over primary cohesivity in interactochemistry of solutions.Balbharti Maharashtra State Board Class 8 Science Solutions Chapter 3 Force and Pressure Notes, Textbook Exercise Important Questions and Answers. For instancewith K3PO4 and K2HPO4 the increase in surface tension has been noticed 1.18 and 2.26% respectively, depending on their structural interactions. The physicochemical data scientifically and quantitatively inferred water + alkali metal phosphates interactions. Ion–ion, ion–dipolar, solute–solvent and intermolecular interactions structurally affected the properties of solvent depicted from magnitudes of surface tension and viscosity. Viscosity B coefficient obtained from Jones–Dole equation inferred solute impact on solvent structure and the size of ionic hydration. Limiting surface tension and viscosity values obtained by fitting Redlich–Kister equation depict stronger ion–water interaction (IWI) than the interactions of water molecules themselves. Viscosities and apparent molal volumeswere used to calculate activation viscous flow energy and entropy changes. Surface tension and viscosity for water + alkali metals (Li, Na, K) were separately measured over their entire composition range at 298.15, 303.15 and 308.15 K.
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