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Science on Vacation! 3 rd /6 th Grade Greenbriar West Elementary By Darren McKnight Fall 2004.

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Presentation on theme: "Science on Vacation! 3 rd /6 th Grade Greenbriar West Elementary By Darren McKnight Fall 2004."— Presentation transcript:

1 Science on Vacation! 3 rd /6 th Grade Greenbriar West Elementary By Darren McKnight Fall 2004

2 Topics Flying to Colorado Driving to Colorado Springs Going to the Top of Pikes Peak Going to the Pool

3 Teaching Strategy Lecture –Reinforce terms from handout provided by GBW –Interactive – use handout as framework, not many answers on the sheets – marks the sheets the students will get Lab –Provide handout for lab groups to use –Draw the approved solution on the board after the lab Test/Quiz –Review concepts from lecture and observations from the lab

4 What is Science? Science is the methods by which people try to explain what happens around them –Why does an apple fall down rather than up? –Why do winds blow? –Why doesnt a swing swing forever? Follows the scientific process –Observations: note physical activity –Hypothesize: propose an if-then explanation –Experiment: organized way to prove or disprove hypothesis by taking data –Conclusions: make summary statement or equation to represent how nature behaves

5 Flying to Colorado Greenbriar West Elementary By Darren McKnight Fall 2004

6 Mass – Key Points What is mass? Does a party balloon have more mass than a candy bar? How do you figure out an objects mass?

7 Mass – Key Points Answers What is mass? –Matter or stuff Does a party balloon have more mass than a candy bar? –Bring in one of each; contrast size vs mass – it depends but probably not How do you figure out an objects mass? –Weigh it; but is mass the same thing as weight? No, will talk about this in a moment; mass of something is the same no matter what but its weight varies…

8 Mass and Inertia Inertia is the measure of resistance to change in motion… –What makes something hard to move? _________ Unless acted upon by an outside force, an object remains at rest or an object in motion stays in motion. –What is an outside force that often causes moving objects to slow down? ______________

9 Mass and Inertia Inertia is the measure of resistance to change in motion… –What makes something hard to move? If it is heavier – has more mass Unless acted upon by an outside force, an object remains at rest or an object in motion stays in motion. –What is an outside force that often causes moving objects to slow down? Friction

10 Force – Key Points What is a force? Why does gravity exert a force on you? If an object is not moving does that mean that there are no forces on it?

11 Force – Key Points Answers What is a force? –Something that pushes or pulls you Why does gravity exert a force on you? –Two objects with mass attract each other, so the Earth pulls the objects towards it If an object is not moving does that mean that there are no forces on it? –It may but it probably means that the forces acting on an object cancel out

12 Forces The man is standing still. Are there any forces on the man? If so, draw them. floor

13 Forces The force due to gravity is the same in size, but opposite in direction, to the force by the floor!!!! Floor Gravity

14 Gravitational Force - Questions So what causes a gravitational force?

15 Gravitational Force - Answer So what causes a gravitational force? –Two objects are attracted to each other Object 2 (has mass) Object 1 (has mass) F1F1 F2F2 F 1 = F 2 Earth Person F F F person = F earth Gravitational force keeps us stuck to the Earth!!! We actually pull on the Earth but the Earth is too big to move!!!

16 Universal Law of Gravitation F = m (GM e /R e 2 ) = mg –Where F = force on an object with mass, m G = gravitational constant = 6.7 x 10 -11 m 3 /kg*s 2 M e = mass of the Earth = 5.94 x 10 24 kg R e = radius of Earth = 6.38 x 10 6 m g = acceleration due to gravity = 9.81 m/s 2 Circle the terms above that are constants

17 Universal Law of Gravitation F = m (GM e /R e 2 ) = mg –Where F = force on an object with mass, m G = gravitational constant = 6.7 x 10 -11 m 3 /kg*s 2 M e = mass of the Earth = 5.94 x 10 24 kg R e = radius of Earth = 6.38 x 10 6 m g = acceleration due to gravity = 9.81 m/s 2 Circle the terms above that are constants –But note that G is the only true constant because if you go to another planet the other terms will vary…

18 Gravitational Force - Questions Is there a gravitational force on a person standing on the moon? –Is it larger or smaller than the gravitational force on the Earth? –Why?

19 Gravitational Force - Answers Is there a gravitational force on the moon? –Is it larger or smaller than the gravitational force on the Earth? The gravitational force is smaller on the moon. –Why? The moon is smaller (less massive) than the Earth. It is actually 1/6 the mass so someones weight on the Moon would be 1/6 of what it would be on Earth –A 90 lb student would weigh only 15 lbs!!!!!!

20 Acceleration Due to Gravity Due to the force exerted as a result of the mass of the Earth an object is accelerated (I.e. the speed increases) when released At time = 0 seconds, an object is released with no velocity One second later, it is going 9.81 m/s Therefore, the acceleration due to gravity is 9.81 m/s per second which is the same as 9.81 m/s 2

21 Science Terms Constant – item that does not change Variables – things in an experiment that change Independent Variable – variable that is changed Dependent Variable – variable that is measured (it depends on the other settings)

22 Weight vs Mass Weight is a force: W = m g –m = mass and –g = acceleration due to gravity = 9.81 m/s 2 m (kg)W (N) 1098 549 12118 552 18177 547 878 Mass, kg Weight, N 0 2 4 6 8 10 12 14 16 18 20 40 0 20 60 80 100 120 140 160 180 PLOT THE DATA!!

23 Weight vs Mass m (kg)W (N) 1098 549 12118 552 18177 547 878 Mass, kg Weight, N 0 2 4 6 8 10 12 14 16 18 20 40 0 20 60 80 100 120 140 160 180 X X X X X X X

24 Weight vs Mass Experiment What observations can you make? What is the constant? What is the independent variable? What is the dependent variable?

25 Weight vs Mass Experiment What observations can you make? –If the mass goes up then weight goes up, plot is a line (I.e. linear relationship) –Highlight that this is a hypothesis!!!!! What is the constant? –Acceleration due to gravity What is the independent variable? –Mass in kilograms What is the dependent variable? –Weight in newtons

26 Why does an airplane fly? This is a review of force concepts What are the four forces on an aircraft and where do they come from?

27 Why does an airplane fly? This is a review of force concepts Thrust – created by engines Lift – caused by flow over wings This is the interesting one!!!! Weight – caused by mass of the aircraft Drag – caused by aircraft surfaces rubbing against air

28 Force Interactions To move forward what must be true? To lift off of the ground what must be true? How is lift created?

29 Force Interactions To move forward what must be true? –Thrust must be greater than drag To lift off of the ground what must be true? –Lift must be greater than weight How is lift created? –Due to the curvature of the aircraft wing the air flows over the top of the wing faster than the bottom of the wing. Air flowing faster creates a lower pressure so the wing is pushed up by the higher pressure on the underside of the wing

30 Lift from a Wing Aircraft Motion wing Air is accelerating around top of wing – drops pressure Pressure From air Pressure From air Since pressure is lower on top than on the bottom of the wing, the wing is pushed up!!!

31 Quiz

32 Quiz Name______________ What is a force? __________________ What are two examples of a force? __________________ __________________ What is energy? __________________ What are two types of energy? __________________ __________________ What is the sum of potential and kinetic energy? __________________ What type of energy is stored when a spring is compressed? ____________________ What is a constant in the spring experiment? ______________________ When the spring is released what type of energy is created? ____________________ Extra Credit: What is another way to store energy in a spring other then compressing it? ____________________

33 Quiz Name______________ What is a force? Action that causes something to speed up or slow down, like a push or pull What are two examples of a force? Gravity, spring, and friction What is energy? Ability to do work What are two types of energy? Potential, kinetic, mechanical, chemical, and electrical What is the sum of potential and kinetic energy? Mechanical energy What type of energy is stored when a spring is compressed? Potential energy What is a constant in the spring experiment? The stiffness of the spring When the spring is released what type of energy is created? Kinetic energy Extra Credit: What is another way to store energy in a spring other then compressing it? Lift it up – stores potential energy as it is moved against the force of gravity KEY

34 Driving to Colorado Springs Greenbriar West Elementary By Darren McKnight Fall 2004

35 Friction – Key Points What is friction? What makes friction greater? What makes friction less? What are examples of friction?

36 Friction Friction is rubbing – force between two surfaces that goes against motion of object –create heat or –slow down motion or –Both Rough surfaces makes friction greater while smooth surfaces make friction less What are examples of friction? Rubbing hands together to get warm Putting sand on the road to prevent cars from sliding Newspaper sliding across the driveway Any more?

37 Friction Three items determine the friction force –YES, FRICTION CREATES A FORCE!!! 1. Goes against the motion 2. Greater if surfaces are rough ; less is surfaces are smooth 3. Friction increases as mass of object increases If we slid a book across the two surfaces below, on which one would the book go farther? Draw the forces on the book (pick one). A B

38 Friction If we slid a book across the two surfaces below, on which one would the book go farther?A A Table Book (gravity) Friction

39 Force Due to Friction Force due to friction, F f –F f = * N Where = coefficient of friction (constant) Where N = mg (weight of the puck acting in opposite direction) If the surface is smoother is the coefficient of friction larger or smaller?________

40 Friction Quiz Is friction a force? (Circle one) Yes No Does friction make an object move faster or does it oppose motion (I.e slow it down) ? ______________ What is the result of friction on spacecraft when they come back through the atmosphere? ________________________________________ If an object has a low coefficient of friction is it smooth or rough? _______________________

41 Friction Quiz Is friction a force? (Circle one) Yes No Does friction make an object move faster or does it oppose motion (I.e slow it down) ? _opposes motion_ What is the result of friction on spacecraft when they come back through the atmosphere? ____it heats up the surface to very high temperatures______ If an object has a low coefficient of friction is it smooth or rough? ____smooth________________

42 Going to the Top of Pikes Peak Greenbriar West Elementary By Darren McKnight Fall 2004

43 Potential and Kinetic Energy – Key Facts What is energy? What is potential energy? What is kinetic energy?

44 Potential and Kinetic Energy – Key Facts What is energy? –Ability to do work Potential energy – stored energy –How can we store energy? Kinetic energy – energy of movement –Ask - How is potential energy converted into kinetic energy?

45 Potential Energy Does the ball have any stored energy here?

46 Potential Energy Does the ball have any stored energy here? NO YES, we moved the ball against gravity (did work)

47 Force Review What forces are acting on the ball while we hold it still above the floor? Draw and label them.

48 Force Review Which force is greater? They are the same, that is why the ball is not moving!!! Force of the hand Force due to gravity

49 Potential Energy What happens when we let go of the ball? If the ball is to move show the direction of the ball. Label the forces on the ball!!!!

50 Potential/Kinetic Energy What happens when we let go of the ball? It starts to fall – has kinetic energy If the ball is to move show the direction of the ball. Label the forces on the ball!!!! Gravity is larger force than air resistance velocity Gravity Air resistance

51 Energy Summary What is the sum of potential and kinetic energy? What are two other types of energy? –

52 Energy Summary What is the sum of potential and kinetic energy? –Mechanical energy What are two other types of energy? – Electrical energy: uses negative charge (e.g. toaster) – Chemical energy: uses chemical reactions (e.g. battery)

53 Energy – Key Facts What is energy? What is potential energy? What is kinetic energy? What is the sum of potential and kinetic energy? What are two other types of energy? –

54 Energy – Key Facts What is energy? –Ability to do work Potential energy – stored energy –How can we store energy? Kinetic energy – energy of movement –Ask - How is potential energy converted into kinetic energy? What is the sum of potential and kinetic energy? –Mechanical energy What are two other types of energy? – Electrical energy: uses negative charge (e.g. toaster) – Chemical energy: uses chemical reactions (e.g. battery)

55 Going to the Pool Greenbriar West Elementary By Darren McKnight Fall 2004

56 Lets Go Play! Liquid, gas, and solid Floating Swim races across the pool – 25m vs 10m

57 Last Night in the Hotel Greenbriar West Elementary By Darren McKnight Fall 2004

58 Dad Wants a Cup of Coffee

59 Electricity Basics - Charge Atoms are made of neutrons, protons, and electrons –Electrons have negative charge Electrons are on the outside of the atom and are easily knocked off When electrons are knocked off then an object gets charged –Positive if the electrons are knocked off –Negative if the electrons that are knocked off cling to the object

60 Materials Related to Charge Some materials hold their electrons very tightly –Electrons do not move through them very well. –These things are called insulators. Plastic, cloth, glass and dry air are good insulators. Other materials have some loosely held electrons, which move through them very easily. –These are called conductors. Most metals are good conductors.

61 Static Electricity How can we move electrons from one place to another? _____________ As electrons move from one atom to another… –Some atoms get extra electrons - net negative charge. –Other atoms lose electrons – net positive charge. –When there is an imbalance of positive and negative charges like this, it is called static electricity.

62 Static Electricity How can we move electrons from one place to another? –Rub two objects together. If they are made of different materials, and are both insulators, electrons may be transferred (or moved) from one to the other. –The more rubbing, the more electrons move, and the larger the charges built up. Scientists believe that it is not the rubbing or friction that causes electrons to move. It is simply the contact between two different materials. Rubbing just increases the contact area between them. As electrons move from one atom to another… –Some atoms get extra electrons - net negative charge. –Other atoms lose electrons – net positive charge. –When there is an imbalance of positive and negative charges like this, it is called static electricity.

63 Charged Particle Behavior If two things have different charges, they attract, or pull towards each other. If two things have the same charge, they repel, or push away from each other. –If they push each other what must there be? ________________ –What is the size of this push dependent on? ___________

64 Charged Particle Behavior If two things have different charges, they attract, or pull towards each other. If two things have the same charge, they repel, or push away from each other. –If they push each other what must there be? force –What is the size of this push dependent on? Charge and distance between the charges FORCE – Coulombs Law F = k (Q 1 Q 2 )/d 2

65 Real Life Observations So, why does your hair stand up after you take your hat off?

66 Real Life Observations So, why does your hair stand up after you take your hat off? –When you pull your hat off, it rubs against your hair. Electrons move from your hair to the hat. –Now each of the hairs has a positive charge. Things with the same charge repel each other. –So the hairs try to move away from each other. –The farthest the hairs can get is to stand up and move away from each other.

67 Electricity – Use Physics for Good Static electricity is about charges that just hang around (I.e. static) Electricity, as we know it, takes advantage of moving charges to do work –What do we call moving charges? __________ –What causes these charges to move? ______________________________________

68 Electricity – Use Physics for Good Static electricity is about charges that just hang around (I.e. static) Electricity, as we know it, takes advantage of moving charges to do work –What do we call moving charges? CURRENT –What causes these charges to move? ELECTROMOTIVE FORCE OR VOLTAGE

69 Electricity Basics – V, i, R Voltage is the amount of electrical force measured in volts –Much like potential energy –A charged particle will accelerate across a voltage difference like a ball being released that is then acted upon by gravity V1V1 V0V0 - Voltage difference created by the two posts of a battery thus causing charges to flow (I.e. CURRENT)

70 Electricity Basics – V, i, R If you want charge to flow in a wire (I.e. electricity) then the flow of charges is called current –Current = i, measured in amperes (or just amps) A wire will not let charges flow without some resistance to their flow, this resistance is called resistance!!! –Resistance = R, measured in ohms –Resistance is like microscopic friction V = i R Ohms Law

71 Effects of Current There are two effects of current –Heating effect Microscopic friction creates heat –Dissipates power (I.e. consumes energy over time): toaster –Magnetic effect Moving charges create a magnetic field –Used in motors and transformers –Makes electricity generation possible (which is the production of current) –Spinning turbine (powered by steam, wind, water or many other ways) turns electromagnets that are surrounded by heavy coils of copper wire inside generators that create magnetic field that causes electrons to flow – CURRENT!

72 Types of Current Direct Current (DC) –Current flows in the same direction all of the time Batteries create DC, usually lower voltages Alternating Current (AC) –Current direction is reversed in direction at regular intervals (e.g. 60 Hz – changes direction 60 times a second - in your house) Electricity used in your home from outlets, higher voltages (120V) Which is better? –DC is more efficient so why do we all have AC in our houses?_______________________________

73 Types of Current Direct Current (DC) –Current flows in the same direction all of the time Batteries create DC, usually lower voltages Alternating Current (AC) –Current direction is reversed in direction at regular intervals (e.g. 60 Hz – changes direction 60 times a second - in your house) Electricity used in your home from outlets, higher voltages (120V) Which is better? –DC is more efficient so why do we all have AC in our houses? For safety reasons, if you grab a high voltage DC line the body will clamp up and not let go, many more electrocutions – all devices driven to AC after original poor safety and human response to DC

74 Power Power is measured in Watts –1500 Watt blow dryer, for example P = i V = current x voltage = V 2 / R We have a 40W light bulb in your house… –How much current is flowing through the light bulb?________ –What is the resistance in the light bulb? ____________

75 Power Power is measured in Watts –1500 Watt blow dryer, for example P = i V = current x voltage = V 2 / R We have a 40W light bulb in your house… –How much current is flowing through the light bulb? P=iV so i=P/V=40W/120V=0.33amps –What is the resistance in the light bulb? V=iR so R=V/i=120V/0.33amps=360 ohms or P=V 2 /R so R=V 2 /P=(120V)2/40W=360 ohms

76 Electricity Basics What are materials that easily pass current? What are materials that do not easily allow current to flow? Can you give examples of each one?

77 Electricity Basics What are materials that easily pass current? –Conductors What are materials that do not easily allow current to flow? –Insulators Can you give examples of each one? –Conductor: copper, steel, etc. –Insulator: wood, glass, clay, etc.

78 Electric Circuits A series circuit has the same current flowing through all components –If one component fails then current stops A parallel circuit has the same voltage drop across each component –If one component fails or is disconnected it does not prevent the flow of current to other components V V i i3i3 i i i i i1i1 i2i2 i = i 1 + i 2 + i 3 i

79 Electric Circuit - Problem For the circuit to the right: –Are the two resistors in series or in parallel? ___________ –What is the total resistance of the circuit? __________ –What is the current flowing through the circuit? ___________ –What is the power dissipated at the first element (I.e. the 360 ohm resistance – like a light bulb)? _______ –Do you think the circuits in your house are wired in series or parallel and why? ____ _________________________________ _________________________________ V 120V R= 360 ohms

80 Electric Circuit - Problem For the circuit to the right: –Are the two resistors in series or in parallel? SERIES – each have same current flowing through them –What is the total resistance of the circuit? 720 ohms – just add together –What is the current flowing through the circuit? V=IR so I=V/R=120V/720ohms=0.166 amps –What is the power dissipated at the first element (I.e. the 360 ohm resistance – like a light bulb)? P=I 2 R (since we know both of these) P=(.166amps) 2 x(720ohms)=20W –Do you think the circuits in your house are wired in series or parallel and why? Parallel because (1) if in series than if one system stops working then current stops flowing and (2) the 120V system would provide varying power to light bulbs rated at the same power based on resistance – like this example, the 40W light bulb (I.e. 360ohms) only gives off 20W (would be dimmer than hoped for) V 120V R= 360 ohms

81 Science on Vacation! Science helps you to learn how to describe what is going on around you! Think – Experiment – Observe –Just like you do with sports, friends, sledding, reading, etc. Do not give up when you first do not understand something –Concentrate, draw a picture, propose a solution

82 Spring 2004 5 th Grade Greenbriar West Think, Experiment, Observe


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