ESSENTIAL PHYSICAL SCIENCE VOCABULARY

Transcription

1 ESSENTIAL PHYSICAL SCIENCE VOCABULARY I. MATTER: ANYTHING THAT HAS MASS AND VOLUME A. mass 1. amount of matter in an object 2. measured in grams B. volume 1. amount of space 2. measured in Liters for liquid and cm 3 for solids C. density 1. amount of matter per unit of volume 2. density = mass / volume 3. less dense floats, most dense sinks D. states of matter 1. defined by shape and volume a. solid: definite shape and volume, particles close together, vibrate in place, lowest energy b. liquid: no definite shape but definite volume, particles slide past one another c. gas: no definite shape or volume, particles are spread out and move fast d. plasma: no definite shape or volume, charged (positive and negative) particles, superheated, most energy E. physical properties 1. properties that can be observed or measured without changing the identity of the substance a. solubility: how well something dissolves b. conductivity: how well something transfers heat or electricity c. malleability: how well something can be pounded into flat sheets (like foil) d. density e. state F. chemical properties 1. properties that describe how easily a substance can change into something new, they are not easily observed a. reactivity: describes how easily a substance interacts with another substance b. flammability: describes how easily a substance catches fire c. combustibility: describes how easily a substance catches fire G. atom 1. smallest unit of matter a. proton: positive particle inside the nucleus b. neutron: neutral particles inside the nucleus c. electron: negative particle that orbits the atom H. molecule 1. 2 or more atoms chemically combined I. pure substance 1. substance in which all the atoms or molecules in a sample look the same; pure substances can be elements or compounds J. element 1. the simplest pure substance made of one type of atom 2.cannot be broken down 3. 3 classes of elements: METALS, NONMETALS, AND METALLOIDS

2 METALS METALLOIDS NONMETALS Good conductors Malleable Shiny Ductile Most= solid semiconductors Might be malleable Some are shiny; some are dull Some are ductile; some are not Poor conductors Non-malleable Dull Not Ductile Most are gasses 4.. or K. compound 1. 2 or more different elements (atoms) chemically combined in a specific ratio 2. compounds can be separated with a chemical change 3. elements in a compound lose their original identities and combine to form something new with new properties 4. L. mixture 1. 2 or more elements and/or compounds physically combined 2. can be separated with a physical change 3. components in a mixture retain their original identity 4. or M. periodic table of elements 1. contains all the elements (113) 2. arranged by atomic number (or NUMBER of PROTONS) 3. period= row 4. group = column (elements in a group share similar properties) N. Law of Conservation of Matter/Mass 1. matter is not created or destroyed 2. total mass in a closed system always stays the same 3. reactants and products

3 II. FORCE: A PUSH OR PULL THAT MAY OR MAY NOT CAUSE A CHANGE IN MOTION A. Newton (unit of measurement) B. balanced force 1. when the net force = 0 Newtons 2. does not cause motion to change C. unbalanced force 1. when the net force > 0 Newtons 2. does cause a change in motion D. net force 1. combination of all forces acting on an object E. friction 1. force that acts in the opposite direction of motion when 2 surfaces are touching 2. rougher surface = more friction 3. more mass/more pushing force = more friction F. gravity 1. the force of attraction between 2 objects with mass 2. gravity depends on mass and distance a. bigger = more gravity b. closer = more gravity 3. without air resistance, all things hit the ground at the same time G. air resistance 1. friction in the air, slows objects down 2. more surface area (size not mass) = more resistance H. inertia 1. an objects tendency to resist a change in motion (an object in motion will stay in motion and an object at rest will stay at rest unless acted upon by an unbalanced force) 2. the more mass, the more inertia I. work 1. W = force x distance 2. measured in Joules (J) 3. work is a transfer of energy from one object to another J. simple machines 1. pulley 2. lever 3. wheel and axle 4. screw 5. inclined plane (ramp) 6. wedge 7. force distance trade off: simple machines can change the amount of force applied or the distance over which it is applied. If one changes the other changes in the opposite way. For example, a ramp reduces the amount of force required but the distance is greater. K. Mechanical Efficiency 1. the idea that no machine is 100% efficient due to friction III. ENERGY: ability to do work A Types of energy 1. potential energy= stored energy a. most potential= highest point; least potential=lowest point 2. kinetic energy = energy of motion

4 b. most kinetic= lowest point/fastest; least kinetic= highest point, slowest. 3. mechanical energy= PE + KE (energy of position and motion) 4. thermal energy=heat 5. sound energy=sound 6. chemical energy=energy stored in compounds (food, batteries etc) 7. electromagnetic energy=light 8. nuclear energy=energy stored in nucleus of atoms 9. electrical energy=energy from moving electrons B. Energy Conversions 1. energy can change from one form to another (conversion) and anytime there is an energy conversion thermal energy is produced but the total amount of energy in the system remains the same. D. Temperature 1. Temperature the measure of thermal energy (heat) 2. Temperature scales: Celsius: used by most of the world, water freezes at 0 o and boils at 100 o Kelvin: used by scientists, water freezes at 273 and boils at 373. Zero on the Kelvin scale is considered absolute zero where all atoms would stop moving. E. Heat 1. Heat is a flow of energy 2. Heat always flows from hotter objects to colder objects 3. Heat travels in three ways a. Conduction: transfer of heat between 2 objects touching b. Convection: transfer of heat is liquids and gases due to density; hot rises cold sinks. c. Radiation: transfer of heat through electromagnetic waves (light) IV. ELECTROMAGNETISM A. Magnetism 1. poles: all magnets have 2 poles (North and South); magnets are always strongest at the poles 2. magnet: an object that attracts iron 3. electromagnet: a magnet created from electricity and an iron core.

5 B. Electricity 1. circuits-a completed loop that contains wires, power source, and load (light, motor etc.) a. series circuit-a circuit in which all the loads are in a single row and the current is shared. b. parallel circuit: a circuit in which there are multiple pathways c. switch: controls the flow of electricity. V. WAVES TRANSFER ENERGY A. Mechanical waves: do not travel thru empty space, needs a medium 1. longitudinal wave (sound waves) a. compression-where particles are close together b. rarefaction-particles are far apart c. which medium does sound travel fastest through? = solid because the particles are closer together in a solid B. Electromagnetic Waves: go thru empty space, does not need medium

6 1. crest-high point 2. trough-low point C. Electromagnetic spectrum- all electromagnetic waves D. Properties of Waves 1. wavelength-distance between 2 equivalent points on a wave 2. amplitude-distance from rest position to crest or trough increased amplitude = increased volume 3. frequency-number of waves in a given time period increased frequency = increased pitch

7 E. Wave Behavior 1. reflection=when a wave bounces off a medium; sound reflection = echo rainbows 2. refraction= bending of a wave as it moves from one medium to another; refraction causes

8 3. diffraction 4. interference Constructive-waves meet and create a larger wave Destructive Interference: waves meet and cancel each other out