♡ Topic 15_Forces and matter ♡

• A fluid can be a liquid or a gas
• In any fluid, the forces due to pressure act at right angles (normal to) the surface
• The equation to calculate pressure is Pressure (Pa) = Force (N) / Area (m²) or P = F / A
• Atmospheric pressure varies with height above the earth's surface because the number of air molecules decreases as you go higher, reducing the weight of air above a point and thus decreasing the pressure
• The pressure in a fluid is determined by the fluid and the atmospheric pressure, making this statement true
• Pressure acts in all directions
• Pressure in fluids increases with depth as the mass of the liquid above the point increases, leading to an increase in force and pressure
• Pressure in fluids increases with density because as density increases, there are more particles in a given volume of the liquid, increasing the weight of the liquid and subsequently the force and pressure
• The magnitude of pressure in liquids at different depths is given by the equation: Pressure (Pa) = Column height (m) x density (kg/m³) x gravitational field strength (N/kg) or P = hρg
• Objects in a fluid experience upthrust because the pressure below the object is higher than above, resulting in an upwards force called upthrust
• To determine if an object will sink or float, compare the upthrust with the weight of the object: if upthrust is greater, it will float; if weight is greater, it will sink
• The magnitude of the upthrust felt by an object is equal to the weight of the fluid displaced by the object
• An object with a density higher than that of water will never float because the upthrust is equal to the weight of the displaced fluid, and with high density, the volume displaced is not enough to produce an upthrust larger than the object's weight, causing it to sink
• It takes more than one force, in different directions, to compress, bend, or stretch an object
• The relationship between the force applied and the extension of an elastic object is that the extension is directly proportional to the force applied, provided that the limit of proportionality is not exceeded
• An inelastic (plastic) deformation is a deformation that results in the object being permanently changed and doesn't return to its original shape when the force is removed
• The equation relating force, spring constant, and extension is: Force = Spring Constant x Extension, with appropriate units being Force (N), Spring Constant (N/m), and Extension (m)
• Elastic potential energy is stored in a spring when it is stretched
• Extension can be replaced with compression in the equation for spring force
• Differentiating between elastic and inelastic distortion: elastic distortion is a temporary change where the object reverts to its original shape once the forces are removed, while inelastic distortion leads to a permanent change in shape
• The work done/stored in stretching a spring can be calculated using the formula: Energy (J) = ½ x Spring constant (N/m) x Extension² (m²) or E = ½kx²
• There is a linear relationship between force and extension when an object is deforming elastically and has not yet reached the limit of proportionality