AP Physics 2 ilə uyğun gələn 585 axtarış nəticələri

Simulyasiyalar

• Atomlararası qarşılıqlı təsirlər (HTML5)
• Atom Qur (HTML5)
• Batareya-rezistor dövrəsi
• Con Travoltaj (HTML5)
• Dalğalara giriş (HTML5)
• Dalğaların interferensiyası (HTML5)
• Diffuziya (HTML5)
• Dövrə yığım dəsti: dəyişən cərəyan (HTML5)
• Dövrə yığım dəsti: dəyişən cərəyan- virtual laboratoriya (HTML5)
• Dövrə yığım dəsti: Sabit cərəyan (HTML5)
• Dövrə yığım dəsti: Sabit cərəyan- virtual laboratoriya (HTML5)
• Enerji Formaları və Dəyişmələri (HTML5)
• Enerji Skeyt Parkı (HTML5)
• Enerji Skeyt Parkı: Əsasları (HTML5)
• Faradey qanunu (HTML5)
• Faradey təcrübəsi
• Fotoelektrik effekt
• Furye sıraları: Dalğa yaratmaq (HTML5)
• Generator
• Hava balonu və statik elektrik yükləri (HTML5)
• Hesablama Qrafikçisi (HTML5)
• Huk qanunu (HTML5)
• Həndəsi Optika (HTML5)
• Həndəsi Optika: Əsasları (HTML5)
• İşığın sınması (HTML5)
• Kepler Qanunları (HTML5)
• Kondensator Labaratoriyası
• Kondensator laboratoriyası: Əsaslar (HTML5)
• Kulon qanunu (HTML5)
• Kütlələr və yaylar (HTML5)
• Kütlələr və yaylar: Əsasları (HTML5)
• Maddənin aqreqat halları (HTML5)
• Maddənin aqreqat halları: Əsasları (HTML5)
• Maqnit və elektromaqnit
• Maqnit və kompas
• Molekullar və İşıq (HTML5)
• Mənim Günəş Sistemim (HTML5)
• Naqildə yaranan rəqslər (HTML5)
• Naqilin müqaviməti (HTML5)
• Nüvə yarat (HTML5)
• Tərəzi laboratoriyası (HTML5)
• Om qanunu (HTML5)
• Plinko Ehtimalı (HTML5)
• Qara cisim şüalanması (HTML5)
• Qazlara Giriş (HTML5)
• Qazların xassələri (HTML5)
• Qravitasiya qüvvəsi laboratoriyası (HTML5)
• Qravitasiya qüvvəsi laboratoriyası: Əsaslar (HTML5)
• Qravitasiya və Orbitlər (HTML5)
• Qüvvələr və hərəkət (HTML5)
• Rezerford səpilməsi (HTML5)
• Rəng Ayırd Etmə (HTML5)
• Rəqqas laboratoriyası (HTML5)
• Sahə İnşaatçısı (HTML5)
• Sahə Modeli ilə Cəbr (HTML5)
• Sürtünmə (HTML5)
• Sıxlıq (HTML5)
• Toqquşma Laboratoriyası (HTML5)
• Təzyiq altında (HTML5)
• Üfüqə nəzərən bucaq altında atılmış cismin hərəkəti (HTML5)
• Vektorların toplanması (HTML5)
• Yüklər və elektrik sahəsi (HTML5)
• Ədəd oxu: Məsafə (HTML5)
• Əyri xətt uyğunluqları (HTML5)
• Alpha Decay
• Balloons and Static Electricity
• Balloons & Buoyancy
• Band Structure
• Battery Voltage
• Beta Decay
• Quantum Bound States
• Buoyancy
• Conductivity
• Double Wells and Covalent Bonds
• Davisson-Germer: Electron Diffraction
• Neon Lights & Other Discharge Lamps
• Electric Field of Dreams
• Electric Field Hockey
• Fluid Pressure and Flow
• Forces in 1 Dimension
• Forces and Motion
• Fourier: Making Waves
• The Greenhouse Effect
• Models of the Hydrogen Atom
• Ladybug Motion 2D
• Lasers
• Lunar Lander
• Masses & Springs
• Maze Game
• Microwaves
• Molecular Motors
• Motion in 2D
• The Moving Man
• Simplified MRI
• Normal Modes
• Nuclear Fission
• Optical Quantum Control
• Optical Tweezers and Applications
• Quantum Tunneling and Wave Packets
• Quantum Wave Interference
• Radiating Charge
• Radioactive Dating Game
• Radio Waves & Electromagnetic Fields
• Ramp: Forces and Motion
• Reactions & Rates
• Resonance
• Reversible Reactions
• Ladybug Revolution
• Semiconductors
• Signal Circuit
• Sound
• Stern-Gerlach Experiment
• Stretching DNA
• The Ramp
• Torque
• John Travoltage

Fəaliyyətlər

• Photoelectric Effect Phet Worksheet (AP Physics 2)
• Gas Properties Phet Simulation worksheet (AP Physics 2)
• PhET Simulations Aligned for AP Physics C
• Lab: Capacitance
• Fluid Pressure and Flow Phet Simulation worksheet
• AP Physics Orbit Lab
• AP Physics PhET Projectile Motion Lab
• Lab: Electric Field & Electric Potential
• Spring Force, Spring Constant and Elastic Potential Energy
• Natural Selection - 7.2 AP BIOLOGY
• The physics of the triple jump
• Circuit Lab 2 - Series and Parallel Circuits
• Springs and Things
• Concept questions for Physics using PhET (Inquiry Based)
• AP Physics Gravity Lab
• Balancing Act Homework Activity 1 and 2
• Lab Photoelectric Effect
• Activity: My Solar System for APP1
• Pendulum Inquiry and Lab Report
• 2D Collision Lab
• Virtual Lab
• Chaos Physics
• Maze Game 1: Using vector representations to move through a maze (Inquiry Based)
• Interactive Photoelectric Effect Lab
• Gravity Force Investigation (AP)
• Photoelectric Effect (AP)
• Gravity Force Lab PreAP using HTML5 Sim
• Conservation of Energy 2: graphs analysis
• Under Pressure
• Mapping Electric Fields
• Sound Simulation Homework II
• Beer's Law: An AP Chemistry Activity
• Wave Interference with Water Waves (AP)
• Algebra-based Physics Semester one lessons, clicker questions, and schedule in pdf (Inquiry Based)
• 'Lectronic Plates
• Salts and Solubility 2: Solubility (Inquiry Based)
• DC Circuit Lab
• Guided Discovery (Chinese/English) for Freshman University Physics: 2. Newtonian Mechanics
• Disoluciones acuosas. Concentración
• The Two-Plate Special
• Waves on a String HTML5 PreAP Lesson
• 2.6 APES: Adaptation & Natural Selection
• Roller Coaster Physics Investigation
• การทดลองที่ 6 คลื่นในเส้นเชือก
• Energy Skate Park Formal Lab
• Equilibrium Inquiry and Experiment Activity
• PhET Lab Energy Skate Park 2
• Simple Pendulum
• Hook's Law
• Reflection and Transmission Interactive Lecture
• การทดลองที่ 11 วงจรไฟฟ้ากระแสตรง
• Movimiento en dos dimensiones: Caso del Proyectil (Two dimensions movement, projectile case).
• Forces & Motion: Basics HTML5 - Part 2 (Friction)
• Circuit Activity 2 Series & Parallel Circuits (Inquiry Based)
• Ramp Activity 2: Calculating Net force on an incline (Inquiry Based)
• Maze Game 2: Vector controls for circular motion (Inquiry Based)
• Vector Addition 2: Understanding Force equilibrium (Inquiry Based)
• Maze game: 2 activities in pdf (Inquiry Based)
• Reactions and Rates 2: Intro to Kinetics (inquiry based)
• Pendulum Lab 2: Find g (Inquiry Based)
• Reactants, Products, and Leftovers Activity 2: Limiting Reactants in Chemical Reactions
• Forca dhe levizja 2
• Maze Game- A Velocity & Acceleration Comparison
• Free-Fall and Projectile Motion
• physics is fun
• Mapping of PhET and IBDP Physics
• Swinging Physics Using Pendulum Phet
• Testing Ideas from Classical and Quantum Physics
• Day 2: Exploring Kinds of Circuits (Series/Parallel)
• Static Pressure
• D.C Circuit Simulation 2 - Series and Parallel
• Exploring Equilibrium 2 (Le Chatelier's Principle)
• Comparing and Ordering Fractins Day 2 of 3
• Circuit activity 2 Series and Parallel Circuits using only CCK (Inquiry Based)
• Getaran Harmonik Sederhana Pada Pegas
• VIRTUAL EXP. - HOOKE LAW
• Physics Graphing and Introduction to Models
• MYP Physics: Gravitational force vs. Distance
• Projectile Motion - Physics 1 lab experiment
• Exploring Equivalence with Rational Numbers: Part 2 Extending to Mixed Numbers
• Universal Gravity-building formula, quantitative with graphing
• Collision investigation lab
• Regents Physics- Projectile Motion Intro
• MYP Physics: Electric Force vs. Distance
• Force and Motion activity 2: Relating graphs and free body diagrams using Moving Man and Forces 1D (Inquiry Based)
• Rasyonel Sayılarda Denklik: Bölüm 2 Bileşik Kesrin Tam Sayılı Kesir Olarak Yazılması
• Explore Balancing Chemical Equations
• Projectile Motion - Physics 1 Lab
• Designing Experiments Using Masses & Springs
• Electric fields
• Pendulum Lab
• Conservation of Mechanical Energy
• My Solar System
• Density Exploration
• Operon Modeling 2.0
• Chemistry - Introduction to Coulomb's Law
• PhET Energy Skate park
• Batterijen in serie en parallel
• Stroomsterkte in een serieschakeling
• Lampjes schakelen
• Stroomsterkte voor en na een lampje
• OSNOVNI ZAKON GIBANJA
• Applied Forces and Friction and a Review of Newton's 1st and 2nd Law
• vectors
• Conservation of Energy Exploration with Skatepark Physics
• Water Waves in an Electric Sink
• Vectors for Physics 1
• Projectiles Air Resistance - It's a Drag
• Charges and Fields
• Battery-Resistor Circuit Simulation Homework III
• Exploring the Energy Skate Park
• Physics Lab Worksheet Momentum.docx
• Gravity Force Lab
• Potential Difference in Circuits
• Discovering the conservation of momentum
• vector addition activity
• Action Potential Simulation - Guided Inquiry Activity
• การบวกลบเวกเตอร์
• LAB การสะท้อนและการหักเหแสง
• LAB การต่อแบตเตอรีและการประยุกต์ใช้งาน
• C.A.S.T.L.E. Unit 2 Labs
• Projectile Motion Lab #2
• Forces in 1 and 2 Dimensions
• 2. Newtonov zakon
• Capacitor and Dielectric 2
• 2. NEWTONOV ZAKON
• Circuitos en serie 2
• Exploring Gravitation
• vector addition
• PhET Collision Lab
• Kinetic Molecular Theory- Introduction (inquiry-based)
• Circuit Construction Kit
• Vector addition worksheet
• Types of Quadrilateral
• Float or Sink? An essay on the density of materials - Part 2
• LR Lab with Simulation Part 2
• PhET Lab Natural Selection 2
• Waves Virtual Lab Part 2
• Newtons 1. und 2. Gesetz
• Undergrad MRI Workshop Activity
• Guided Discovery (Chinese/English) for Freshman University Physics: 5. Introduction to Waves
• Guided Discovery (Chinese/English) for Freshman University Physics: 6. Wave Interference
• Guided Discovery (Chinese/English) for Freshman University Physics: 1. Kinematics
• Guided Discovery (Chinese/English) for Freshman University Physics: 3. Energy & Momentum
• Guided Discovery (Chinese/English) for Freshman University Physics: 4. Rotations & Oscillations
• Computer Simulations as a Tool to Assist Teaching Basics of Electromagnetism (Simulações Computacionais Como Ferramenta Auxiliar ao Ensino de Conceitos Básicos de Eletromagnetismo)
• Projectile motion
• Magnetism
• Friction Experiment
• Capacitor Lab: Basics: Inquiry into Capacitor Design
• Vector Addition Worksheet
• Vectors worksheet
• PhET Lab States of Matter Basics
• Horizontal Launch Investigation
• Ispitivanje fotoelektricnog efekta pomocu PhET simulacije
• Waves on a String AP1
• Davisson Germer lecture and homework
• Alpha Decay investigations
• Balancing Chemical Equations - Guided Inquiry Activity
• Identifying the Limiting Reactant
• Werkblad simulatie kracht en beweging klas 2
• Quantum Wave Interference, 2 Lasers, PhET, Worksheet
• Quest for the Coulomb Cup
• Finding Wave Properties
• Hooke's Law inquiry lab
• Middle School - Electric Circuits
• Middle School - series and parallel circuits
• Projectile motion worksheet
• Projectile Motion Experiments
• Visualizing Mixing with Sugar and Salt Solutions
• Gene Regulation Guided Simulation
• Gases Understanding physical properties of gases (Inquiry Based)
• Isotopes and Atomic Mass - Guided Inquiry Activity
• Electrolyte and Non-electrolyte Solutions - Interactive Lecture Demonstration
• Molecule Polarity - Guided Inquiry Activity
• Gravity and Orbits-Vector Concept
• States of Matter Lecture Demonstration
• Coeficientes e raízes das Funções do 1° e 2° Grau
• EM wave analogy tutorial
• Density-introduction
• Electrostatics Simulation lab
• Introduction to Discharge Lamps
• How to make a laser
• Understanding the Photoelectric Effect
• Wave Particle Duality
• Intro to Photoelectric Effect Interactive Lecture
• Probability and Randomness Interactive Lecture
• The Photoelectric Effect and Work Functions
• Rutherford Experiment
• Beta Decay Investigations
• Circuit activity 3 Combination Circuits (Inquiry Based)
• Atomic models homework (Inquiry based)
• Horizontal projectile motion
• Forces and Motion: Finding the Mass of a Car
• Cruce y persecución de 2 móviles con movimiento rectilíneo y uniforme (MRU)
• (BNCC) Flutua ou Afunda? Um ensaio sobre a densidade dos materiais - Parte 2
• Bouncing Off the Walls
• Pixel Peeping
• Cavendish Lab
• Climate Change - Gas
• Gravity Force Lab Guided Inquiry
• Net force
• Linear momentum
• Projectile Motion
• Projectile motion
• Projectile Motion
• Vector Addition
• projectile motion
• Milk Trucks
• Teoria zinetikoa. Materiaren egoera fisikoak eta uraren egitura berezia.
• Guided lab with instructions, screenshots and questions
• MRI lecture and homework
• Stern Gerlach clicker questions
• Types of Forces Investigation
• Modeling Paradigm Lab- 2nd Law
• Saturated Solutions - Interactive Lecture Demonstration
• Investigation of a Solution’s Color (Qualitative and Quantitative) - Guided Inquiry Activity
• Plate Tectonics
• Build an Atom
• Waves Intro‌ Remote Lab ‌
• Escalando Formas Actividad y Lección
• Energy Skate Park - Concept Questions Compendium
• Build a Molecule - Molecular Formulas and Coefficients
• Fuerzas en una rampa (actividad de indagación)
• Pendulum Lab 1: Intro to pendulum (Inquiry Based)
• Conservation of Energy 1: Introduction (qualitative approach)
• Intro y laboratorio virtual de Tiro Parabólico
• My mystery number
• Pushing Things Around
• Greased Lightning
• Fluid Experiments
• Projectile Motion - developing understanding.
• Projectile Motion
• The Ramp Mechanical Advantage and Efficiency
• Projectile Motion
• Energy Skate Park Lab Questions
• Worlds of Wonder
• Simple Pendulum
• Energy Chains
• projectile motion
• Projectile Motion (Lab Report)
• Build an Atom - Guided-Inquiry Activity
• Reactants, Products, and Leftovers Review Activity: Limiting Reactants in Chemical Reactions Review
• Exploring Equivalence with Rational Numbers: Part 1 Fractions less than or equal to 1
• Wave Modeling and Wave addition (Inquiry Based)
• Presión hidrostática por indagación
• construye una Molécula - Formulas moleculares y coeficientes
• Formulas y nombres de moléculas
• Expresiones Algebraicas
• ¿Qué tan bien la curva describe los datos?
• Densidad, actividad con la simulación
• pH Scale
• Mass/Spring Activity
• Radioactive Decay, Fission and Chain Reactions
• Experiencia Educativa Principio Arquimedes, Fuerza Boyante y Densidad (Learning experience: Archimedes principle, Buoyant force & Density).
• PhET Energy Forms and Changes Virtual Lab
• Projectile Motion Discovery
• Simple Pendulum Investigation Lesson Plan
• Energy Skate Park Lab (html5)
• Energy Simulation
• Ενεργειακά Διαγράμματα
• Bending Light Student Worksheet
• Crash!
• D.C Circuit Simulation 1
• Photoelectric Effect
• Exploring Fission (inquiry)
• Forces and Newton's Laws Review
• Bose-Einstein Condensation Lesson
• Fractions 3 Day Unit
• Densità
• Escala de pH, introducción a ácidos y bases con indagación
• Introduction to Inequalities
• Waves Interference Remote Labs
• Intro: Gravedad y Orbitas
• Energy Skate Park Basics: Mechanical Energy Lab
• Balance in the up-and-down
• Atomic Interactions PhET Exploration - with Coulomb's Law application
• Blackbody Spectrum
• Conservation of Energy (Energy Skate Park)
• Current in DC Circuits
• Introduction to Fourier Analysis
• Investigation of LR Circuits
• Build an Atom
• Experimental Design with Forces
• Gravity and Orbits Lesson
• Circuits 3 Day Unit
• Fracciones Equivalentes
• Colission Lab colorado
• Explorando el equilibrio
• Indagación con la clase entera: Ley de Beer & Lambert
• Introducción a los estados de la materia
• Introduzione ai vettori
• Introduction to vectors
• Projectile Motion Lab
• Kinetic Molecular Theory
• Investigating waves
• Lunar Lander/ Fun Game
• Electromagnetic Generation - Phet simulation
• Electromagnetic Induction
• Making STABLE Atoms Lab
• Projectile Motion Simulator
• Lesson plan
• Vector Addition Worksheet
• Photoelectric Effect
• Projectile Motion
• Quantitative Predictions of Projectile Motion
• Momentum Lab
• Projectile motion and horizontal component of its velocity
• Waves on a String and Wave Interference Virtual Labs
• Circuits lab manual with experimental& theoretical value comparison
• Interacciones atómicas Exploración PhET
• Group data generating activity to find Lac Operon effectiveness
• Energy Skate Park Basics Lesson
• Balloons and Static Electricity
• Force and Motion Basics - Second grade
• Projectile Parabolas
• Density Lesson (with Putty Lab)
• Hot Air Balloons Lesson
• Energy Forms Simulation Activity
• Driven Oscillation
• Balancing Chemical Reactions Game
• Air Resistance Lesson
• Električni otpor i Ohmov zakon
• Friction lab report
• PRIMARIA: Alineación con programas de la SEP México (2011 y 2017)
• Investigación del color de una solución (cualitativa y cuantitativa) - Actividad de consulta guiada
• fuerzas sobre un resorte
• Energía mecánica
• Introducción al movimiento del péndulo
• Equilibrio en el sube y baja
• explorando ondas en una cuerda
• Introducción a las colisiones
• Energía térmica y cambios de estados
• Hablemos de temperatura
• Fenomenos magnéticos
• Explorando circuitos CD
• Sonidos altos y bajos
• Reflexión y refracción de la luz
• Explorando circuitos RLC
• Explorando variables de la electricidad
• Explorando el funcionamiento de un condensador
• Explorando enteros
• Media artimética con PhET y GeoGebra
• Introducción a los vectores
• Explorando fracciones
• Leyes de Kirchhoff
• Ley de Coulomb
• Parametros Estadisticos
• Juego de numeros
• Asociacion de capacitores
• Fuerzas sobre un resorte II
• Aparatos de medicion electricos
• Bailando al son de las razones
• Matemáticas futboleras ¿y la mediana?
• Una torta de jamón con fracciones
• A física do salto triplo
• La fisica del salto triplo
• Introduccion al campo eléctrico
• Introduction aux vecteurs
• La Física del salto triple
• Introdução aos vetores
• Équilibre de la balançoire
• La physique du triple saut
• Equilíbrio na gangorra
• Equilibrio in su-e-giù
• Parliamo di temperatura
• Moving Man I: Velocity vs. Time Graphs
• Moving Man II: Acceleration vs. Time
• Ohm's Law, Kirchhoff's Laws, Resistors in Parallel and Series Lab
• Radio Waves & Electromagnetic Fields Simulation Homework
• Microwaves Simulation Activity
• Microwaves Simulation Homework
• Introduction to Energy Model
• Circuit Lab 1 - Properties of Electric Circuits
• Coulomb's Law for Chemistry
• Percobaan gelombang pada tali
• Magnets, Electromagnets and Ohm's Law Lab!
• Forces and Motion Lesson
• States Lab
• Exploración cuantitativa de la Fuerza de Gravedad
• Equality Explorer: Homework + Class Venn Diagram
• simple pendulum lap
• Lab Experiment
• Simple Pendulum
• การทดลองOnline 1 เรื่อง ลูกตุ้มนาฬิกาอย่างง่าย
• Natural Selection Lesson by UTeach
• vectors
• Unidad de Circuitos (actividad para 3 sesiones)
• Área y Perímetro
• Hoja de Actividades de Ciencias: Soluciones Ácido Base
• Photoelectric Effect
• Modeling Gravity
• Moving Man Motion Graph Review
• Circuit Principles and Applications
• Projectile launch angle vs displacement
• Addition and Resolution of Vectors
• Charges and Charged Objects Investigation
• Hooke's Law and Spring Constant with Energy: Regular Level
• Horizontal Projectile Motion
• Greenhouse effect activity
• PHET Charges and Fields Activity Part 1
• Charges and Fields Exploration
• Guided Manual-Worksheet of ideal gas
• Forces in 1 Dimension
• Chemistry Theater
• Second Law Inquiry PhET Forces and Motion
• Virtual Lab - Investigating Refraction of Light
• motion along straight line with constant acceleration
• Resistance and Resistivity
• Pendulum Energy
• Vectors Addition
• Potential Energy of A Spring (Elastic Potential Energy)
• Serie de Labs virtuales de Ondas
• Laboratorio Virtual de Visión del Color
• Waves on a String Discovery Activity
• Beer's Law Lab: Introduction to Beer's Law
• The x and y's of Gas Properties
• Determinine Electric Field Relationships
• Guided Manual-Worksheet of ideal gas
• Modelos Atomicos
• Undersøgelse til Stoftilstande Basis
• Introducción a Circuitos Eléctricos
• Serie de actividades para Electrostática: de Electrización, Campos y Fuerzas
• Laboratorio virtual de reflexión y refracción de la luz
• project motion
• Projectile Motion
• U1S6L2 Ley de gravitación universal
• Turning Forces
• Density
• Using the Gases Intro PhET Simulation: Concept Development for Understanding Gas Laws and the Variable Changes Associated with Them
• Isótopos y Masa Atómica: Actividad de Consulta Guiada
• Laboratorio virtual de Condensadores
• Transcripción y Traducción
• Vector Activity
• The Two-Slit Experiment
• Activity: Wave on a String
• Resistivity in a wire
• Rubric for Simple Pendulums - What Affects the Period?
• MS and HS TEK to Sim Alignment
• Graphing Energy at the Skate Park
• Electric Field Hockey Post-Game Analysis
• El ruido y la contaminación acústica en mi ciudad
• Kracht en Beweging. Google Quizen
• Moving Man with Position and Velocity graphs
• Intro to Circuits
• Kennismaken met bewegingsdiagrammen en versnelling
• Newton's Gravitational Constant Calculation
• Laboratorio de capacitores con y sin dieléctrico.
• Virtual Lab - Circuit Basics
• Soluciones: Unidades de Concentración
• Atividade de Força e Movimento
• Hooke's law
• Construye un átomo (indagación)
• Laboratorio virtuale di circuiti
• Waves Virtual Lab Part 1
• Preguntas conceptuales: Neurona
• Hojas de trabajo y preguntas sobre Energía
• Construire un atome
• CD's, DVD's & Optical Commmunication: Binary Coding and Diffraction Errors
• UNIDAD3 S14 L4 Ley de Ohm
• Opladen door wrijving, influentie, geleiders en isolatoren - Google Quiz - guided inquiry
• Tectónica de placas e a abertura e expansão do fundo dos oceanos.
• Cinco Numeritos para Jugar
• Online Assignment 4 Ms & Ss
• Energiebehoud in het skatepark klas 5
• Zekering gebruiken als beveiliging tegen Kortsluiting en overbelasting.
• Ndertimi i qarqeve elektrike ne seri
• 大一物理引導式自我發現 (中文/英文): 動力學 (牛頓定律)
• Medición del Ph de sustancias ácidas y básicas