Science 7: Density of Irregular Shape
ESSENTIAL QUESTIONS: 1.How do you calculate the density of irregularly shaped objects? 2.How can calculating density help determine the identity of an unknown substance? Volume •The amount of space an object takes up. •Measured with a graduate. Units - milliliters Displacement - The difference between the initial volume (110ml) and the volume after an object is submerged (175 ml). Mass •The amount of matter in an object. •Measured with a triple beam balance or a scale. •Units – grams Density •Measure of how compact a substance is in a given volume. •The more molecules in a given volume the greater the density. •The fewer molecules in a given volume the less the density. How do you calculate density? Density = Mass Volume Units – g/ml or g/cm3 Why do things float? •Objects with a density greater than 1 will sink in water. (Closely spaced) •Objects with a density less than 1 will float in water. (Less closely spaced) What careers may use density? •Geologist - to identify minerals. •Chemical Engineers - to identify liquids and other substances. •Ship builders -to determine if ship will float. Science 8: Sound Waves How Do Sound Waves Travel Through Different Materials: VIDEO: https://goo.gl/J7tVuG VIDEO RESOURCES: http://www.physicsclassroom.com/Physics- Interactives/Waves-and-Sound/Simple-Wave- Simulator/Simple-Wave-Simulator-Interactive https://www.youtube.com/watch?v=GkNJvZINSEY&list=PL9R 7yvC-KlZmzwKwZpmyXutF5GMBsruL1 ESSENTIAL QUESTIONS: 1.What is sound? 2.How do sound waves travel? 3.How do physical properties of a medium affect the speed of sound waves? 4.What properties of waves affect what we hear? 5.What is the Doppler effect? Sound •Vibrations that travel through the air or other media •When these vibrations reach the air near your ears you hear the sound. How Sound Travels •Sound waves carry energy through a medium (solid, liquid or gas) without the particles of the medium traveling along. •Sound travels as a longitudinal wave. How Sounds are Made •Longitudinal waves are generated when a source of energy forces the matter in a medium to vibrate. •This back-and-forth motion pushes air particles together, generating a compression, or moves the particles apart, generating a rarefaction. Medium •Sound waves must have a medium to travel through. •Gas – air is the most common •Liquid •Solid •In outer space there are no molecules to compress or rarefy, so sound does not travel through outer space. Speed of Sound •Depends on the physical properties of the medium it travels through. •Elasticity •Density •Temperature •At room temperature, sound travels through air at about 342m/s. Physical Properties of Media •Elasticity – the ability of a material to bounce back after being disturbed •Solid materials are usually more elastic than liquids or gases. •Particles of a solid do not move very far, so they bounce back and forth quickly as the vibration travels through the object, allowing faster motion. •Density – how much matter there is in a given amount of space •The speed of sound depends on how close together the particles of the substance are in the medium. •Temperature - degree or intensity of heat present in a substance or object •In a given media (solid, liquid, gas), sound travels more slowly at lower temperatures. Properties of Sound Waves •Intensity •Loudness •Frequency •Pitch Properties of Sound Waves •Intensity – the amount of energy the wave carries per second through a unit of area •Amplitude increases with increased energy •Measured in watts per square meter (W/m2) •Loudness – describes what you actually hear. •Though not the same as loudness, the greater the intensity of a sound wave, the louder it is. •Measured in decibels (dB) •Maximum safe level is 85 dB •Frequency – the number of vibrations that occur per second •Wavelength changes with frequency •Measured in Hertz (Hz) •50Hz = 50 vibrations per second •Pitch – a description of how high or low the sound seems to a person •High frequency = high pitch •Low frequency = low pitch •Example: a young girl might have a squeaky (high pitched) voice, an older man might have a deep (low pitched) voice Doppler Effect •The apparent change in frequency as a wave source moves in relation to the listener •Sounds moving toward a person – Waves are at a higher frequency, so pitch appears to increase (high) •Sound moving away from a person – Waves are at a lower frequency, so pitch appears to decrease (low) ------------------------------------------------------------------------------------------------------------- Explain how each of these properties of media affect the speed of sound. 1. Elasticity___________________________________________________________ ___________________________________________________________________ _______________________________________________________________ 2. Density____________________________________________________________ ___________________________________________________________________ ________________________________________________________________ 3. Temperature_______________________________________________________ ____________________________________________________________________ ____________________________________________________________________
SCIENCE 7: Density of Regular Shaped Objects. Compare mass of "old" & "new" Pennies
www.youtube.com/watch?v=hZMZT64XoJM SCIENCE 8: WAVES 101 SCIENCE 7: DENSITY of regular shaped objects
Essential Questions: 1.How do you calculate the density of regularly shaped objects? 2.How can calculating density determine the identity of an unknown? Density •The ratio of an object’s mass to its volume. •Density = Mass /Volume Volume •The amount of space taken up by a quantity of matter •Often measured in cubic centimeters (cm3) •1cm3 = 1 ml volume = L X W X H Mass •The amount of matter in an object •Measured with a triple beam balance or a scale •Units – grams Density of a material remains the same regardless of how much of the material is present. SCIENCE 8: WAVES 101 Essential Questions: 1.How do matter and energy interact when waves are generated? 2.What are the three main types of mechanical waves? 3.What are properties of waves? •Transverse Waves •Longitudinal Waves •Surface Waves Wave Vocabulary •Crest – where the displacement of the medium is at a maximum •Trough – where the displacement of the medium is at a minimum •Rest position – where the medium shows no disturbance. Amplitude •The vertical distance between a peak or a valley and the resting position in a transverse wave. •A measure of how compressed or rarefied the medium becomes in a longitudinal wave.
SCIENCE 7: Inland Sea video on formation of earth's crust, volcanoes, basalt, subduction.
SCIENCE 8: Inland Sea video to discuss index fossils and Law of Superposition. Science 7: Identifying Atoms, Molecules, Compounds and Mixtures SCIENCE 8: Comparative Anatomy: Homologous, Analogous and Vestigial Structures
SCIENCE 7: Describe the atomic composition of simple molecules
SCIENCE 7: Building Background knowledge on the History of the Atom video clip below.
Science 8: Embryology and the Theory of Evolution
SCIENCE 7: RING OF FIRE & PLATE TECTONICS
SCIENCE 8: INDEX FOSSILS. View the video below. |
Erik E. Mason
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