Praxis 5005 Physical Science (2023/2024) Already Graded A

Praxis 5005 Physical Science (2023/2024) Already Graded A Matter takes up space and has mass Mass a measure of the amount of matter in an object Weight the measure of the Earth's pull of gravity on an object Volume the amount of cubic space that an object occupies Density the mass of a substance contained per unit of volume Specific gravity the ratio of the density of a substance to the density of water Physical properties of matter can be observed or measured without changed the composition of the substance (can be undone) ex: odor, speed of evaporation, color, melting/freezing, mass, taste Chemical properties of matter substance usually changes into another kind of substance ( cannot be undone) ex: lemon juice turning brown when heated Law of conservation of matter matter or mass cannot be created or destroyed, it can change from one form to the next; the amount of mass will be the same before and after Compound two or more elements that have been chemically combined ex: NaCl (salt) Mixture any combo of two or more substances in which the substances keep their own properties -homologous mixture is a solution Elements a basic structure that cannot be simplified (hydrogen, gold, oxygen, etc); made entirely from one type of atom Atom the smallest amount of an element; made up of protons (+ electrical charged), neutrons (carry no electrical charge) and electrons (- electrical charge) Molecule the smallest particle of a substance that can exist independently and still have all of the properties of that substance -composed of atoms Motion objects is in motion when it is continuously changing its position relative to a reference point Speed rate at which distance is covered during motion/rate of change of its position (distance / time) ex: mph, m/s Distance length of path it takes (speed X time) Time duration over which movement or motion occurs (distance/ speed) Acceleration measurement in change in an objects velocity; an object can decrease speed, increase speed, or change direction Formula: vf-vi change in velocity/change in time Circular motion movement of an object along the circumference of a circle or rotation along a circular path or a circular orbit; speed does not change but direction is changing constantly (velocity); when the velocity changes, the object is undergoing accelerated motion and acceleration is always directed toward the center Relative motion the calculation of the motion of an object with regard to some other object; reference point is important b/c we do all calculations according to reference point Newton's first law of motion Law of inertia: an object at rest will remain at rest and an object in motion will remain in motion at a constant velocity unless acted upon by an external force Newton's second law of motion if a net force acts on an object, it will cause the acceleration of the object F = ma force = mass x acceleration Newton's third law of motion for every action there is an equal and opposite reaction Friction a force that holds back the movement of a sliding object; acts in an opposite direction to movement; mechanical energy transforms into thermal energy ex. car stopping b/c of the friction between the brakes and the wheels Centripetal force when an object moves in a circular path, a force must be directed toward the center of the circle in order to keep the motion going Newton's universal law of gravitation every object in the universe attracts every other object with a force directed along the line of centers for the two objects that is proportional to the product of their masses; the more the masses of the objects the larger the gravitational force between them Kinetic energy energy in motion ex: moving water and wind Potential energy energy measured in the amount of "work" it does; stored energy ex: ball sitting at top of hill Law of conservation of energy energy can be transformed from one form into another or transferred from one region to another but cannot be created or destroyed Simple machine device for doing work that only has one part; redirect or change the size of forces allowing work with less muscle effort Waves (in physics) disturbance or oscillation, that travels through matter or space, accompanied by a transfer of energy Reflection when a wave strikes a reflective surface, it changes direction, such that the angle made by the incident wave and the line normal to the surface equals the angle made by the reflected wave ex: echo or reverberation Interference two traveling waves which exist in the same medium will interfere with each other; if their amplitudes add it is constructive interference and if they are "out of phase" and subtract, they are destructive interference Refraction the bending of waves when they enter a medium where their speed is different (more important with light than sound) Diffraction the bending of waves around obstacles and the spreading out of waves beyond small openings ex: thunder Electromagnetic spectrum -Radio waves -Microwaves -Infrared radiation -Visible light -Ultraviolet -X-rays -Gamma rays Concave mirror light is reflected such that angle of incidence equals angle of reflection and they all meet at point called focus or focal point; image is REAL, UPSIDE DOWN, and SMALLER Convex mirror rays will divert or move apart thereby no meeting at a point; image is VIRTUAL, UPRIGHT and SMALLER Convex lens light refraction in lens where rays meet at focal point on other side of lens; image is REAL, INVERTED and SMALLER; used for farsightedness so focal point focuses closer (on) to retina Concave lens slight refraction in lens where rays diverge on other side of lens; image is VIRTUAL, UPRIGHT and SMALLER; used for nearsightedness so focal point focuses further (on) to retina Conduction transfer of heat between substances that are in direct contact with each other; the better the conductor the more rapidly heat will be exchanged ex: metal Convection occurs when warmer areas of liquid or gas rise to cooler areas in the liquid or gas; cooler liquid/gas then takes place of warmer areas which have risen higher; continuous circulation ex: water boiling Radiation method of heat transfer that does not rely upon any contact between the heat source and the heated object; heat can be transmitted through empty space by thermal radiation called infrared radiation ex: heat from sun, released from filament of bulb Refraction of sound if the air above the earth is warmer than that of the surface, sound will be bent downward toward the surface Conductor of electricity an object or type of material that allows the flow of electrical current in one or more directions ex: metal, carbon, water, silver (most conducive of all), copper, aluminum, gold, brass Resistor of electricity resistor is anything that electricity can not travel through easily; when electricity is forced through a resistor, often the energy in the electricity is changed into another form of energy, such as light or heat; the reason a light bulb glows is that electricity is forced through tungsten, which is a resistor; the energy is released as light and heat