Pressure Science PDF

Pressure Between Solids Definition of Pressure: Pressure is the force exerted per unit area. Pressure=Forcce / area , Measured in Pascals (Pa), where 1 Pa = 1 N/m². Factors Affecting Pressure Between Solids: o Force: The greater the force applied, the greate...

Pressure Between Solids Definition of Pressure: Pressure is the force exerted per unit area. Pressure=Forcce / area , Measured in Pascals (Pa), where 1 Pa = 1 N/m². Factors Affecting Pressure Between Solids: o Force: The greater the force applied, the greater the pressure. o Area: The smaller the area of contact, the greater the pressure (inverse relationship). Examples: o Sharp objects like knives and needles exert high pressure because the force is concentrated over a small area. o Snowshoes spread the weight over a larger area, reducing pressure and preventing sinking into snow. Applications in Everyday Life: o Car tires: Wider tires distribute the vehicle's weight over a larger area, reducing pressure on the ground. o Bed of nails: If enough nails are used, the body’s weight is distributed across the nails, reducing pressure at each point and preventing injury. 2. Pressure in Liquids Definition: Pressure in liquids is caused by the weight of the liquid and acts equally in all directions. Hydrostatic Pressure: The pressure at a given point in a liquid increase with the depth due to the weight of the liquid above it. Characteristics of Pressure in Liquids: o Increases with depth. o Depends on the density of the liquid.  o Acts equally in all directions (important in understanding how submarines and hydraulic systems work). Examples: o Water pressure increases as you dive deeper into the ocean. o Dams are thicker at the bottom to withstand greater water pressure. 3. Pressure in Gases Gas Pressure: Caused by the movement and collision of gas particles with the walls of their container. Factors Affecting Gas Pressure: o Temperature: Higher temperature increases the speed of gas particles, leading to more collisions and higher pressure. o Volume: Reducing the volume of a container increases the frequency of collisions, increasing pressure o Number of Particles: More gas particles result in more collisions and higher pressure (directly proportional). Examples: o A balloon expands when air is blown into it, as the gas pressure inside increases. o A car tire feels harder in hot weather because the gas pressure inside the tire increases with temperature. 4. Particles on the Move Particle Theory of Matter: All matter is made up of tiny particles (atoms, molecules, ions) in constant motion. This movement differs in solids, liquids, and gases: o Solids: Particles vibrate in place, tightly packed in a fixed structure. o Liquids: Particles move more freely, but are still close together. o Gases: Particles move rapidly and freely, spreading out to fill any available space.  Kinetic Energy and Temperature: o The temperature of a substance is directly related to the average kinetic energy of its particles. o Higher temperature = faster particle movement (increased kinetic energy). Diffusion: The process by which particles spread out from an area of high concentration to low concentration due to their random motion. Brownian Motion: The random movement of particles in a fluid (liquid or gas) as they collide with other particles. Visible under a microscope when tiny particles (like pollen) move in water. Applications: o Smelling perfume across the room (gas diffusion). o Mixing food coloring in water (liquid diffusion).