GENSCI TERM 1 REVIEWER

I. SIMPLE AND COMPOUND MACHINES

A. Simple Machines - makes work easier by changing the size or direction of a force

• Lever
• Wheel and Axle
• Pulley
• Inclined Plane
• Wedge
• Screw

- An inclined plane wrapped around a cylinder (Screw, jar lid)

B. Compound Machines Examples: Bicycle - wheel and axle + levers Scissors - two levers + wedges Wheelbarrow - lever + wheel and axle Can opener - wheel and axle + lever + wedge

II. TRANSLATIONAL AND ROTATIONAL MOTION A. Translational Motion - Translational motion occurs when an object moves from one position to another. Example: A car moving along a straight road.

Types of Translational Motion Rectilinear motion – movement in a straight line Curvilinear motion – movement along a curved path

B. Rotational Motion - Rotational motion occurs when an object spins around an axis.

Examples: A spinning wheel A rotating fan Earth's rotation Important Terms

Axis – an imaginary or real line around which an object rotates. Rotation – the turning of an object around its axis.

C. Linear Velocity - Linear velocity describes how quickly an object changes its position in a particular direction. ^^ Formula: v = d / t Example: If a car travels 100 m in 5 s: v = 100 m / 5 s v = 20 m/s

D. Angular Velocity - Angular velocity describes how quickly an object rotates. ^^ Formula: ω = θ / t Angular velocity is commonly measured in radians per second (rad/s).

For a rotating wheel: v = rω

E. Motion of Wheels and Vehicles

• * When a wheel rolls without slipping:

The wheel has rotational motion because it spins. The vehicle has translational motion because it moves forward. Thus, a moving wheel demonstrates both translational and rotational motion.

• * REMEMBER:

Wheel spins - rotation Vehicle moves forward - translation

III. FLUID MECHANICS AND HYDRAULICS A. Pascal's Principle - Pressure applied to an enclosed fluid is transmitted equally in all directions throughout the fluid.

Applications: Hydraulic brakes Hydraulic lifts Hydraulic jacks Hydraulic presses Hydraulic Systems

Hydraulic systems use liquids under pressure to transmit force. The basic relationship is: P = F / A For an ideal hydraulic system: F₁/A₁ = F₂/A₂

• * A small force applied to a small piston can produce a larger force on a larger piston.

IV. ARCHIMEDES' PRINCIPLE AND BUOYANCY A. Archimedes' Principle - An object immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object.

Buoyant Force Fᵦ = weight of displaced fluid The buoyant force acts upward.

B. Buoyancy - Buoyancy is the upward force exerted by a fluid on an object placed in or on the fluid.

• Floating
• Sinking
• Neutral buoyancy

Buoyant force = weight Object remains suspended in the fluid

V. DENSITY - Density is the amount of mass contained in a given volume.

Formula: ρ = m / V In water:

Density < 1 g/cm³ → generally floats Density > 1 g/cm³ → generally sinks Density = 1 g/cm³ → neutral buoyancy

More dense - tends to sink Less dense - tends to float

VI. ELECTRICITY AND ENERGY EFFICIENCY A. Electric Current - Electric current is the flow of electric charge through a conductor. (A)

B. Voltage - Voltage is the electrical potential difference that drives electric charges through a circuit. (V) - push that drives current.

C. Resistance - Resistance is the opposition to the flow of electric current. (Ω) - slows down the flow of current.

D. Ohm's Law ^^ formula: V = IR ; I = V/R ; R = V/I

VII. LIGHT AND SOUND A. Reflection - Reflection is the bouncing back of light when it hits a surface. - Example: Seeing yourself in a mirror.

Law of Reflection Angle of incidence = Angle of reflection

B. Refraction - Refraction is the bending of light as it passes from one medium to another because its speed changes. - Example: A straw appearing bent when placed in a glass of water.

C. Diffraction - Diffraction is the bending or spreading of waves when they pass through an opening or around an obstacle. - Example: sound being heard around a corner.

REFLECTION - bouncing REFRACTION - bending due to change of medium DIFFRACTION - spreading/bending around openings or obstacles

VIII. SOUNDPROOFING AND AMPLIFICATION A. Soundproofing - Soundproofing reduces the transmission of sound from one area to another.

Materials commonly used include:

• Foam
• Fiberglass
• Thick curtains
• Carpets
• Acoustic panels

B. Sound Amplification - Amplification increases the strength or loudness of a sound signal.

Examples:

• Microphones
• Speakers
• Amplifiers

SOUNDPROOFING - reduces sound transmission AMPLIFICATION - increases sound signal

IX. LIGHT INNOVATIONS A. Lasers - Light Amplification by Stimulated Emission of Radiation - A laser produces a highly concentrated beam of light.

Characteristics:

• Very directional
• Can be highly intense
• Relatively narrow beam
• Used in many scientific, industrial, communication, and medical applications

Examples:

• Laser surgery
• Barcode scanners
• Optical communication
• Cutting and engraving

B. Holograms - A hologram is a three-dimensional-looking image produced using light interference and diffraction.

Uses:

• Security features
• Identification cards
• Displays
• Scientific and technological applications

C. LED Technology - Light-Emitting Diode. - LEDs produce light when electric current passes through a semiconductor.

Advantages:

• Energy efficient
• Long-lasting
• Produces relatively little heat compared with many older *lighting technologies
• Available in many colors

D. Medical Applications of Light - Light-based technologies are used in medicine for:

• Laser surgery
• Vision correction procedures
• Phototherapy
• Imaging and diagnosis
• Treatment of certain skin conditions
• Optical instruments

Important: Different wavelengths of light have different effects and medical uses.

X. LOUIS PASTEUR - french chemist/ scientist/microbiologist whose work greatly contributed microbiology & medicine

A. Germ Theory - Germ theory states that many diseases are caused by microorganisms. - Pasteur provided important experimental evidence against the idea that microorganisms spontaneously appear from nonliving matter.

B. Swan-Neck Flask Experiment - Pasteur used swan-neck flasks containing nutrient broth.

What happened? The broth was boiled to kill microorganisms. Air could still enter the flask. The curved neck trapped dust and microorganisms. The broth remained free of microbial growth as long as contamination was prevented. When the broth was exposed to trapped contaminants, microorganisms could grow. - Microorganisms came from existing microorganisms in the environment, not from spontaneous generation.

No contamination - no microbial growth

C. Vaccination

- vaccination helps the immune system develop protection against specific infectious diseases. - Pasteur contributed to the development of vaccines, including vaccines for: anthrax & Rabies

Vaccine - prepares the immune system to recognize and fight a pathogen.

D. Sterilization and Food Safety - Pasteur's work helped establish the importance of controlling microorganisms in food and other materials.

Pasteurization - controlled heat treatment used to reduce harmful microorganisms in foods and beverages while maintaining their quality.

Pasteurization ≠ Sterilization Pasteurization - reduces harmful microorganisms. Sterilization - aims to eliminate all viable microorganisms.

< Germ theory - microorganisms can cause disease Swan-neck flask - evidence against spontaneous generation Vaccination - helps develop immune protection Pasteurizaton - controlled heating to reduce harmful microorganisms >

XI. HOUSEHOLD CHEMICALS A. Sodium Hypochlorite - NaOCl - Household bleach - Disinfecting products uses: Disinfection Whitening Removing stains

never mix bleach with acids or ammonia

B. Sodium Carbonate - Na₂CO₃ - washing soda. Uses: Cleaning Laundry Water softening

It is more strongly alkaline than baking soda.

C. Sodium Bicarbonate - NaHCO₃ - baking soda. Uses: Baking Cleaning Deodorizing Neutralizing some acids

D. Sodium Lauryl Sulfate - SLS - surfactant (substance that helps water spread, mix with substances, and remove oils and dirt.) Found in: Soaps Shampoos Toothpaste Detergents

E. Sodium Fluoride - NaF used in: Toothpaste Dental-care products

Fluoride helps strengthen tooth enamel and helps prevent dental cavities.

XII. GOVERNMENT AGENCIES A. FDA – Food and Drug Administration - responsible for regulating certain products to help protect public health, including areas such as: Food Drugs Cosmetics Medical devices Other regulated health-related products

FDA - Food, Drugs, and health-related regulated products

B. DENR – Department of Environment and Natural Resources - Responsible for environmental protection and management of natural resources. Areas include: Forests Wildlife Biodiversity Natural resources Environmental management

DENR - Environment + Natural Resources

C. DTI – Department of Trade and Industry - Helps regulate and promote trade and industry and protects consumers in areas covered by its mandate. Areas include: Business and industry development Consumer protection Product standards Trade