Title Notes_Pressure and Buoyancy_Pressure and Buoyancy.pdf ✅

www.thinkiit.in Page 1 thinkIIT THRUST AND PRESSURE (A) Thrust :  The force acting normally on surface is called 'thrust'.  This is a vector quantity.  It is measured in newton (N). (B) Pressures :  The thrust on an unit area of a surface is called 'pressure'.  Pressure = Area Thrust or P = A F  Unit : The SI unit of pressure is newton per meter square or N/m2 , other units of pressure are pascal and bar.  One Pascal : One pascal is defined as the pressure exerted on a surface area of 1m2 by a thrust of 1 newton.i.e. 1 Pascal = 1 N/m2  Some examples based on pressure  Inserting a pointed nail in a wooden block is an easier task than to insert a rod inside a wooden block with the same force because the nail has a smaller area and thus it will experience more pressure even with the same force.  A sharp knife cuts better than a blunt knife.  While walking, a man exerts more pressure on the ground in comparison to when he is standing.  Pressure in fluids  A substance that can flow is called a 'fluid'.  liquids and gases are considered as fluids.  Laws of pressure  Pressure exerted by the liquid is the same in all directions about a pt.  Pressure exerted is the same at all pts in a horizontal plane as well as in a stationary liquid.  Pressure at a pt inside a liquid increases with depth from the free surface.  Pressure at a particular depth is different for different liquids, i.e. P = hdg where, h = height of the column of liquid. d = density of the liquid g = acceleration due to gravity  The pressure exerted anywhere in a confined liquid is transmitted equally and undiminished in all directions throughout the liquid which is called 'Pascal's law'. (A) Hydrostatic Pressure : The normal force (or thrust) exerted by a liquid at rest per unit area of the surface in contact with it is called "pressure of liquid or hydrostatic pressure." PRESSURE & BUOYANCY