• TYPES OF ENERGY

UNIT 10 – PHYSICS - WORK, POWER & ENERGY – PART 2

 

  • Energy exists in nature in several forms such as Kinetic Energy, Potential Energy, Heat Energy, Chemical Energy etc. The sum of the kinetic and potential energies of an object is called its mechanical energy.

 

  • PRESSURE: Pressure is defined as force acting per unit area. Pressure = force/area. The SI unit of pressure is Newton per meter squared or Pascal.

 

 

 

 

  • The same force acting on a smaller area exerts a larger pressure, and a smaller pressure on a larger area. This is the reason why a nail has a pointed tip; knives have sharp edges and buildings have wide foundations.
  • All liquids and gases are fluids. A solid exerts pressure on a surface due to its weight. Similarly, fluids have weight, and they also exert pressure on the base and walls of the container in which they are enclosed, Pressure exerted in any confined mass of fluid is transmitted undiminished in all directions.

 

  • All objects experience a force of buoyancy when they are immersed in a fluid. Objects having density less than that of the liquid in which they are immersed, float on the surface of the liquid. If the density of the object is more than the density of the liquid in which it is immersed, then it sinks in the liquid.

 

  • ARCHIMEDES’ PRINCIPLE: When a body is immersed fully or partially in a fluid, it experiences an upward force that is equal to the weight of the fluid displaced by it.
  • Archimedes’ principle has many applications. It is used in Designing Ships and Submarines.
  • LACTOMETERS, which are used to determine the purity of a sample of milk and HYDROMETERS used for determining density of liquids, are based on this principle.

 

  • DENSITY AND RELATIVE DENSITY: The mass per unit volume of a substance is called its density. The SI unit of density is kilogram per meter cubed. Density = mass/volume.

 

  • The RELATIVE DENSITY of a substance is the ratio of its density to that of water: Relative density = Density of a substance/Density of water. Since the relative density is a ratio of similar.
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