1. Chapter 3: Forces & Pressure Form 4 1 Physics Next > The study of matter

2. Objectives: ( what you will learn ) 1) understanding Pressure 2) understanding the Principles Physics: Chapter 3 2 < Back Next >

3. Pressure 3 Pressure = force per unit area If a fluid (liquid or gas) has a density ρ , its pressure P , at a point due to the fluid of height h , is given by P = ρ gh where g = gravitational field strength For a given point in the fluid, its pressure acts equally in all directions . It does not depend on the shape of containers. Therefore, for a given liquid, its pressure: - increases with depth - increases with density < Back Next > Pressure, P = Force , F Area , A , N m -2 or Pa (Pascal)

4. 4 Atmosphere Atmosphere is the layer of thick air which surrounds the Earth. The pressure exerted on the Earth’s surface by the atmosphere is the atmospheric pressure , which can be measured using Fortin barometer or Aneroid barometer. 1 atmosphere = 760 cm Hg = 10.3 m water = 101,300 Pa 1 millibar = 100 Pa < Back Next >

5. 5 The Principles Pascal’s Principle: The pressure applied to an enclosed liquid is transmitted equally to all parts of the liquid. Archimedes’ Principle: When an object is immersed in a fluid the buoyant force on the object is equal in size to the weight of fluid displaced by the object. Bernoulli’s Principle: When the velocity of a fluid increases, the pressure of the fluid decreases. < Back Next >