Physical Science

1. Law of Universal Gravitation – • A. greater the mass = the greater the force of gravity • B. greater the distance = the less the force of gravity • Mass – the amount of matter an object takes up. • Weight – the amount of gravitational force on an object • Newton’s Laws of Motion: • An object at rest remains at rest and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force. (inertia) ex. Car stops – you keep going. • The acceleration of an object depends on the mass of the object and the amount of force applied. • Force = mass x acceleration(F=m x a) • Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. Ex. Rocket launch – gases down, rocket up • Momentum – depends on objects mass and velocity = m x v • The Law of Conservation of Momentum – Any time objects collide, the total amount of momentum stays the same. • Pressure= amount of force exerted on a given area • Pressure = force / area (atmospheric pressure =14.7 lb/sq. in) • Buoyant Force – upward force that keeps object floating • Archimedes principle – buoyant force of an object in a fluid is an upward force equal to the weight of the fluid that the object takes the place of or displaces. • ex. Duck weight = 9 N, buoyant force = 9, duck floats, rock weight = 75 N, buoyant force = 50 N, rock sinks • Density – mass per unit of volume D = mass/volume, objects with density > 1 (water) sink, density < 1 float, change density by changing shape, mass or volume. Physical Science Ave. speed = total distance ex. 10 m = 2 m/s time 5 sec Velocity = speed + direction ex. 2 m/s East Acceleration – rate at which velocity changes over time (m/s2) Accel = (final velocity – initial velocity)Vf – Vi time T Centripetal Acceleration – an object traveling in a circular motion is always changing direction which causes its velocity to change, so it is always accelerating Force – push or pull, measured in Newtons (N) Net Force – combination of all forces acting on an object. (ex. 10 N <- and 25 N -> = 15 N ->) Friction – a force that opposes motion between 2 surfaces that are in contact types: static (not moving), Kinetic (rolling, sliding) Gravity – force of attraction between 2 objects due to their mass. (Newton) Acceleration due to Gravity = all objects accelerate to earth at a rate of 9.8 m/s2 (v = 0, 9.8, 19.6, 29.4 m/s) Free fall – only force acting on an object is gravity (no air resistance/drag) Orbiting objects are in free fall. Centripetal Force – cause objects to orbit –move in a circular path Projectile Motion – curved path that an object follows when thrown or launched = horizontal + vertical velocities Terminal Velocity – when net force is 0 (drag = gravity), object stops accelerating.

2. Types of simple machines: 1. Lever– bar that pivots on a fixed pt. (fulcrum) 3 types (see pic) 2. Pulleys – consists of a wheel over which a rope, chain or wire passes. 3. Wheel & Axle – 2 circular objects of a different sizes. 4. Inclined Planes – straight slanted surface ex. Ramp 5. Wedge – 2 inclined planes that move ex. Knife 6. Screw – inclined plane wrapped in a spiral around a cylinder Compound Machines – made up of 2 or more simple machines. Ex. Can opener – wheel & axle, wedge, lever Bernoulli’s Principle – as the speed of a moving fluid, increases, the fluid’s pressure decreases. This causes lift (upward force) on airplane, curve ball. Pascal’s Principle – a change in pressure at any point in an enclosed fluid will be transmitted equally to all parts of that fluid. Ex. Press foot on brake exerts pressure on a cylinder of fluid – pressure is transmitted to all parts of liquid filled brake system to stop car. Work – the transfer of energy to an object by using a force that causes the object to move in the direction of the force (measured in joules) Work = force x distance (W = f x d) 80 N x 2 m = 160 J Power – rate at which energy is transferred. Power = work/time (P = w / t) Machine – device that makes work easier by changing the size of direction of the force. Mechanical Advantage – a number that tells how many times a machine multiplies force. Mechanical advantage (MA) = output force500 N = 10 input force 50 N Mechanical Efficiency – comparison of work output with work input = work output/work input x 100 Energy – the capacity to do work 1. Kinetic – energy of motion KE = mv2 / 2 ex. KE = 1, 200 kg x (20 m/s)2 / 2 = 240,000 Joules 2. Potential – energy an object has because of its position Gravitational potential energy (GPE) = weight x height

3. Forms of Energy 1. Mechanical energy = potential energy (PE) + kinetic (KE) 2. Thermal (Heat) – from random motion of atoms 3. Chemical – from bonds of atoms in molecules ex. Food, gas 4. Electrical – from moving electrons 5. Sound – from vibration of particles 6. Light – from electromagnetic waves (micro, UV, X-rays) 7. Nuclear – from changes in the nucleus of atoms 8. Elastic – from stretching or compressing Energy Transformation/Conversion – change from one form of energy to another ex. Blender (electrical to mechanical) ex. Photosynthesis = radiant (light) to chemical (sugar) Law of Conservation of Energy – energy cannot be created or destroyed but can be changed from one form to another. Energy Resources 1. Nonrenewable – cannot be replaced or are replaced more slowly than they are used. ex. Fossil fuels – coal, oil, natural gas, petroleum – made from swamp plants millions of years ago 2. Renewable – can be replaced at the same rate they are used. ex. Solar, Hydropower (water), Wind, Geothermal (heat from earth), Biomass (plants, wood, waste) Temperature – measure of how hot something is – the average kinetic energy of the particles in an object. (thermometer) Temperature Scales: 1. Fahrenheit (F) – boiling 212 F, body 98.6 F, room temp = 68 F, water freezes 32 F 2. Celsius ( C ) - boiling 100 C, body 37 C, room temp = 20 C, water freezes 0 C 3. Kelvin (K) - boiling 373 K, body 310 K, room temp = 293 K, water freezes 273 K Absolute zero – lowest temp on Kelvin scale = 0 K – all molecular motion stops. Heat – the energy transferred between objects that are at different temperatures. Thermal energy – total kinetic energy of all particles that make up a substance. Heat transfer –convection (circulation of gas/liquid), radiation (electromagentic waves), conduction (contact) Thermal Conductivity – rate at which a substance conducts thermal energy (metal higher than cloth) Specific Heat – the amount of energy needed to raise a 1 kg of a substance by 1 C (ex. Water 4,184) Heat = specific heat x mass x change in temperature ex. H = 4,184 x .2 kg x (80-25 C) = 42.024 Joules States of Matter: Solid, liquid, gas Properties of Matter:Physical (texture, shape, size, color, odor, volume, mass, weight, and density) Chemical (ability to react, conductivity) Changes in Matter: 1. Physical changes – melting, freezing, boiling 2. Chemical changes – rust, burning, color or odor change

4. Column I - Alkali Metals Column 2- Alkaline Earths Columns 3-12- Transition elements Column 17 - Halogens Column 18 - Noble Gases What is the difference between a compound and a molecule? A molecule is formed when two or more atoms join together chemically. A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds. Types of Bonds Covalent – share electrons – between 2 non-metals ex. CO2 Ionic – transfer electrons – between metal and nonmetal ex. Fe2O3 Conservation of Mass Mass cannot be created or destroyed, although it may be rearranged in space, and changed into different types of particles. In any chemical process in a closed system, the mass of the reactants must equal the mass of the products. Must balance the chemical equation In this example, Na2SO4 and CaCl2 are the reactants and CaSO4 and NaCl are the products. Oxidation numbers = positive & negative charges