Electrical and Mechanical Resistance

Definition: The opposition that a substance offers to the flow of electric current.
Formula: ( R = \frac{V}{I} )
- ( R ) = resistance (ohms, Ω)
- ( V ) = voltage (volts, V)
- ( I ) = current (amperes, A)
Factors Influencing Resistance:
- Material: Conductors (low resistance) vs. insulators (high resistance).
- Length: Longer conductors increase resistance.
- Cross-sectional Area: Larger area decreases resistance.
- Temperature: Most materials increase resistance with temperature.

Definition: The opposition to deformation in materials when subjected to an external force.
Types:
- Static Resistance: Resistance to initial movement.
- Dynamic Resistance: Resistance when in motion.
Factors:
- Material Properties: Stiffness, ductility, and elasticity.
- Surface Interaction: Friction between surfaces in contact.

Conductivity vs. Resistivity:
- Conductivity: Measure of a material's ability to conduct electric current (high in metals).
- Resistivity: Material property indicating how strongly it opposes current flow; varies with temperature.
Common Materials:
- Conductors: Copper, aluminum.
- Insulators: Rubber, glass, plastics.
- Semiconductors: Silicon, germanium, used in electronic devices.

Definition: The ability of an organism to resist or withstand harmful factors (e.g., pathogens, toxins).
Types:
- Innate Resistance: Natural defenses (skin, mucous membranes, immune cells).
- Adaptive Resistance: Acquired through exposure or vaccination (antibodies).
Factors:
- Genetics: Inherited traits that enhance resistance.
- Environment: External factors influencing immune response.

Definition: A form of exercise that improves muscular strength and endurance by exerting force against resistance.
Types of Resistance:
- Constant Load: Weightlifting with free weights or machines.
- Variable Load: Bands, cables that change resistance through the movement.
Benefits:
- Increases muscle mass, bone density, and metabolic rate.
- Improves overall functional strength and endurance.
Training Principles:
- Progressive Overload: Gradually increasing resistance to enhance strength.
- Repetitions and Sets: Typically involves 8-12 reps for strength training, 15+ for endurance.
Safety Considerations: Focus on proper form to prevent injury; warm-up and cool down are crucial.

Definition: Material's resistance to electrical current flow
Formula: ( R = \frac{V}{I} ), where (R) is resistance (ohms), (V) is voltage (volts), and (I) is current (amps)
Factors:
- Material: Conductors (low resistance, e.g., copper) versus insulators (high resistance, e.g., rubber)
- Length: Longer conductors have higher resistance
- Cross-sectional Area: Larger area decreases resistance
- Temperature: Most materials increase resistance with higher temperature

Definition: Opposition to deformation when a material is subjected to an external force
Types:
- Static: Resistance to initial movement
- Dynamic: Resistance when in motion
Factors:
- Material Properties: Stiffness, ductility, and elasticity affect resistance.
- Surface Interaction: Friction between surfaces influences resistance

Conductivity: How well a material conducts electric current, high in metals
Resistivity: Material's opposition to current flow, varies with temperature
Common Materials:
- Conductors: Copper, aluminum, good conductors
- Insulators: Rubber, glass, plastics, resist electrical current flow
- Semiconductors: Silicon, germanium, used in electronic devices, conduct "in-between" conductors and insulators

Definition: An organism's ability to withstand harmful factors like pathogens or toxins
Types:
- Innate: Natural defenses like skin, mucous membranes, and immune cells
- Adaptive: Acquired through exposure or vaccination
Factors:
- Genetics: Genes can influence resistance levels
- Environment: External factors affecting immune response

Definition: Exercise that improves muscular strength and endurance by applying resistance
Types:
- Constant Load: Using weights (free weights or machines)
- Variable Load: Resistance changes during movement, like using bands or cables
Benefits:
- Increased muscle mass, bone density, and metabolic rate
- Improved overall functional strength and endurance
Training Principles:
- Progressive Overload: Gradually increase resistance to enhance strength
- Repetitions and Sets: Typically 8-12 reps for strength, 15+ for endurance
- Safety: Proper form is crucial to prevent injury, warm-up and cool-down are essential