Grade 11 General Science: Fluids and Electricity

Fluid: Any substance that flows and takes the shape of its container, encompassing both liquids and gases.
Fluid Mechanics: The branch of physics studying the behavior, movement, and forces (pressure, gravity, friction) of fluids at rest or in motion.
Density ( $\rho$ ): Mass contained per unit volume ( $\rho = \frac{m}{V}$ ).
- SI Unit: $\text{kg/m}^3$
- Common Unit: $\text{g/cm}^3$
- Higher density means more mass is packed into the same volume.
Volume ( $V$ ): The space occupied by a substance.
- SI Unit: $\text{m}^3$
- Common Units: $\text{cm}^3$ , $\text{L}$ , $\text{mL}$
Viscosity: A fluid's internal resistance to flow.
- High Viscosity (Thick): Honey, syrup, motor oil (flow slowly).
- Low Viscosity (Thin): Water, alcohol, gasoline (flow quickly).
Pressure ( $P$ ): Force applied per unit area ( $P = \frac{F}{A}$ ).
- SI Unit: Pascal ( $\text{Pa}$ ).

Blaise Pascal: French scientist who discovered that pressure applied to a fluid in a closed container is transmitted equally in all directions.
Pascal's Principle Formula: $\frac{F_1}{A_1} = \frac{F_2}{A_2}$ where $F$ is force and $A$ is area.
Hydraulic Systems: Systems utilizing liquids (usually oil) to transfer force efficiently because liquids cannot be easily compressed.
Applications: Hydraulic car jacks, hydraulic brakes, barber chairs, excavators, and forklifts.

Archimedes: Ancient Greek mathematician, physicist, engineer, and inventor (287–212 BC).
Buoyancy: The upward force exerted by a fluid on an object.
Archimedes' Principle: An object submerged in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object.
Buoyant Force Formula: $F_b = \rho g V$
- $F_b$ = Buoyant Force ( $\text{N}$ )
- $\rho$ = Fluid density ( $\text{kg/m}^3$ )
- $g$ = Acceleration due to gravity ( $9.8\,m/s^2$ )
- $V$ = Volume of fluid displaced ( $\text{m}^3$ )

Electricity: Energy produced by the movement of electrons, powering modern light, communication, and machinery.
Renewable Energy Sources: Sources that naturally replenish.
- Hydropower (flowing or falling water)
- Solar energy (sunlight captured via solar panels)
- Wind energy (moving air turning turbine blades)
Nonrenewable Energy Sources: Limited resources subject to depletion.
- Coal (burned to produce steam that turns turbines)
- Natural gas (burned to generate heat for turning turbines)

Overloading: Occurs when excessive current flows through wires because too many devices are connected to one circuit or outlet.
Warning Signs: Warm outlets or plugs, burning smells, flickering/dimming lights, and frequently tripping circuit breakers.
Associated Risks: Damage to appliances, melted wires, electrical fires, and electric shock.
Circuit Breaker: A safety device that automatically shuts off power flow during a short circuit or overload.
Safety Practices: Avoid daisy-chaining extension cords, distribute high-power appliances across separate circuits, inspect cords regularly, and turn off unused appliances.