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TURBO TAKS Week 6 Lesson 1: Body Systems Lesson 2: Heat Transfer & Waves Lesson 3: Energy & Electricity Lesson 4: Motion, Forces, & Physics Equations Lesson 1: Body Systems The Human Body must also maintain homeostasis (a balance). The organs of the body work together in organ systems to perform specific functions. Organ systems are often connected and work together to allow the body to function. Integumentary: Skin, hair, nails: Protects, prevents infection, temperature control Skeletal Support and protection of organs. Muscular Uses bones as simple machines to exert force on the body to create movement. Nervous Control system of the body. Works with other systems to maintain homeostasis. Endocrine Secretes hormones that circulate in the blood stream and tell other systems what to do. Reproductive: produces gametes in ovaries and testis. Circulatory: transports oxygen and nutrients to cells and removes wastes. Respiratory Brings O2 to circulatory system and removes CO2 (gas exchange!). Immune Fights infection Helper T-cells and macrophages turn on the immune response and start attacking invaders. Digestive: breaks down food and absorbs nutrients Excretory Takes waste from the blood stream for removal from the body. Lesson 2: Heat Transfer and Waves Heat Transfers • Heat moves from hot to cold. • Example: When you put your hand on a lab table it feels cold because the heat in your hand is leaving your body and transferring down, into the table. Not the other way around. 25oC 10oC – Heat from the 25oC block is sinking into the 10oC block – Heat does not rise, hot air rises. Conduction Conduction transfers from one substance to another by direct contact of molecules. THINK: Solids Example: When you touch a hot stove! slow transfer 5oC 25oC metal wood 25oC fast transfer 5oC Convection Convection transfers heat through moving currents in fluids (gases or liquids). Convection cannot occur in solids, because solids can’t move. • THINK: Liquids and Gases Hot air rises sunshine wind wind warm ground Cold air is pulled in from the sides causing wind. Much of the weather on earth comes from convection currents. The sun warms air at the surface of the earth. Warm air rises, causing winds. When the air cools it falls back to the ground. Much of the weather on earth comes from convection currents. The sun warms air at the surface of the earth. Warm air rises, causing winds. When the air cools it falls back to the ground cooler liquid falls Hot liquids (and gases) are less dense and rise, causing Hot convection currents. Liquid These currents Rises transfer heat cooler throughout the liquid liquid (or gas). falls Heat Source Radiation Heat (thermal energy) in the form of electromagnetic radiation from a light source. All energy on earth comes originally from the sun. Only radiation can travel through the vacuum of space to the earth. Radiation • Examples: • The sun warming your face. • Warmth you feel sitting close to a campfire. Radiation transfers heat through electromagnetic waves — pure thermal energy. Lets Practice CONVECTION Name the type of heat transfer: 1. Boiling water in a pot. 2. Your feet burning on concrete in the Summer time. CONDUCTION 3. McDonalds keeping french fries warm under a heat lamp. RADIATION A 20ºC 4. Which letter represents a possible heat transfer? 20ºC B D 30ºC 40ºC C D (Always hot cold) . Waves A wave is any disturbance that transmits energy through matter or space Types of Waves 1. 2. Types of Waves • 1. Compression/ Longitudinal wave • Produced by moving a slinky spring back and forth. • Example: Sound Types of Waves • 2. Transverse Wave • Produced by waving a rope or other medium up and down • Example: Light wave, or a ripple in a pond Parts of a Transverse Wave Characteristics of All Waves • Wavelength- distance from a point in a wave to the next point on the next wave in the same phase • Frequency- the number of times that a repeated event occurs per second • For sound, High pitch = high frequency • V=f λ Short Wavelength = High Frequency Long Wavelength = Low Frequency (Velocity = frequency x wavelength) Wave Properties • Reflection • When waves bounce off a hard boundary. • The sound waves are bouncing off the tank. (i.e.- mirror, echo) • Refraction • The bending of light as it passes from one medium into another. (i.e.- lenses) Wave Properties • Diffraction • Occurs when a wave bends around a corner. • Interference • A wave interaction that occurs when two or more waves overlap. Wave Properties • Resonance • Occurs when one object vibrates because of another object’s vibrations. • Common in tuning forks and other musical instruments • Example: Earhearing • Body of guitar vibrates because of it’s strings vibration. (Fast-forward to about 30 sec in. Turn speakers to low volume.) Lets Practice • Answer with: Reflection, Refraction, Diffraction, Interference, or Resonance. 2. Using a mirror 3. Water waves passing 1. Lenses through an opening. REFRACTION 4. When the primary colors of light combine to form white light INTERFERENCE REFLECTION 5. When singing near a piano, the keys can start to sound. RESONANCE DIFFRACTION Lesson 3: Energy and Electricity (Can fastforward to 20 seconds) Energy • Energy is the ability to cause motion or forces; the units of energy are joules (J). Potential Energy • 1. Gravitational Potential Energy (in Joules, J) is stored energy, because an object is above the ground. • More height = more Potential Energy. It has the potential to cause motion and forces. Potential Energy (in Joules) Ep = mgh mass (in kilograms) height (in meters) acceleration due to gravity (9.8 m/s2 ) Potential energy equals mass times gravity times height. • Gravitational Potential Energy= mass x gravity x height Potential Energy • The acceleration due to gravity we experience on Earth is 9.8 m/s2. In space, gravity is 0 m/s2. Don’t forget to use the given constants and formulas! • Potential Energy Practice: Ex: How much potential energy does a 4 kg object have that is 5 meters off the ground? m == 4 kg m hh == 5 m 2 gg == 10 m/s EEpp == ? Ep = mgh Ep = (4)(10)(5) = (40)(5) = 200 Joules Kinetic Energy • Kinetic Energy (in Joules, J) is the energy of motion. Moving objects have kinetic energy. • Kinetic Energy= ½ mass x velocity2 mass (in Kinetic kilograms) Energy 2 E = (½)mv k (in velocity (in m/s) Joules) Kinetic energy equals one-half Times mass times velocity squared. • Mass is measured in kilograms (kg) and velocity is measured in meters/second (m/s). Energy Transfers • Energy can be transferred from one type to another. • Work (in Joules, J) is • Power (in Watts, W) how forces change energy. is how fast work is done. • Work=Force x Distance • Power = Work Time Work (in Joules) W = Fd Force (in Newtons) Distance (in meters) Power (in Watts) P = W/T Work (in Joules) Time (in seconds) Efficiency • Efficiency is the percentage of energy retained (not lost) in an energy transfer. Energy gained by the object (in J) Efficiency (in %) Wout Eff x100 Win Energy you tried to give the object (in J) Efficiency Calculation Work In: How much energy you tried to give to the object thru an energy transfer or work. Here work is done on the object, pulling it up the ramp. This is the total energy that you tried to give the object. Work put in 240 J. Win=Fd= 30(8)=240 J Work Out: How much energy is actually gained by the object (how much it got out). The object only got out 200 J. After 10 kg 2m Wout=Epgained Wout Eff x100 =mgh Win =10(9.8)2 Ep =98(2) Eff x100 = 196J W 196J 200 x100 240 J 100 .82 .83 xx 100 =82% = 83% Types of Energy • Thermal Energy—Heat energy. A product of most other forms of energy. • Mechanical Energy—Any kind of Kinetic (moving) or Potential (height) Energy. • Electrical Energy—Energy of moving electrons: lightening, electricity. • Radiant Energy—Light energy from light bulbs or the sun (renewable solar energy). • Chemical Energy—Stored in • Nuclear Energy—Energy from chemical bonds. Includes energy in food, plants, and batteries (produce electricity by combining chemicals). nuclear reactions (radiation): makes huge amounts of energy, but also long-term, radioactive waste like power plants. Lets Practice Match with the terms to the right: WORD BANK 1. The units for energy. a) Kinetic Energy 2. The ability to create forces or motion. b)Potential Energy 3. Energy because of an object’s motion. c)Energy 4. Energy because of an object’s position above the ground due to gravity. d)Height 5. Vertical distance above the ground. e)Joules Electricity • Moving of electrons through conductors. The path must be closed, or electrons cannot move. Electrical Circuits • Series Circuit • Provides a single conducting pathway without junctions. • Parallel Circuit • When two or more components of a circuit are connected across junctions, providing separate pathways for the current. Which type of circuit would you rather have for your Christmas lights? Parallel, so that if one light burns out, the current can still reach the other bulbs. Assuming the chart contains all energy transformations in the Earth system, how much solar radiation Subtract all the energy goes toward evaporating water? expenditures from the F 40,000 terajoules total amount reaching G 92,410 terajoules Earth. H 121,410 terajoules J 133,410 terajoules 173,410 – 52,000- 81,000 – 370 – 40 = 40,000 Lesson 4: Motion, Forces, and Physics Equations Speed and Velocity • Speed is the distance an object travels per second. • Velocity includes the speed of an object and the direction of its motion. Distance travelled (in meters) Time (in seconds) Speed d v = (in t meter/sec) Speed equals the distanced traveled divided by the time it took to move that distance. d s t d t v= • They share a formula on your equation sheet. Measuring Speed To measure speed you must determine the distance traveled and the elapsed time. Initial Position Distance Traveled Final Position 25 m 0:00.0 Elapsed Time 5 sec 0:05.0 D 25m S 5m/s T 5sec a= Acceleration Acceleration is how fast you change velocity OR how much the velocity changed in a certain amount of time. An object accelerates when it changes speed OR changes direction! Acceleration (in m/s2) ΔV a= ΔT Change of Velocity (in meters/sec) Acceleration equal change of velocity divided by change of time. V V final Vinitial , so, a Change of Time (in seconds) V final Vinitial T ΔV ΔT If acceleration is unknown use acceleration due to gravity out of the constants box on the formula chart! Solving for Acceleration 1. Calculate initial velocity 2. Calculate final velocity Measure ΔT (Time it took to Accelerate) Measure Vi (Initial Velocity) 0.0 4m 3. Determine the change in time. 4. Plug into acceleration equation. Measure Vf (Final Velocity) Accelerates for 2 seconds 1.0 D 4m Vi T 1sec Vinitial 4m/s So ΔT = 2 sec a V f Vi 84 2 T 4 Vinitial 2m/s 2 2 8m 3.0 4.0 D 8m T 1sec V final 8m/s Vf MOMENTUM • Momentum is how hard it is to stop something and is a product of an object’s mass and its velocity. Momentum is increased if either the mass or velocity is increased. Mass (in kg) Momentum (in kgm/sec) p = mv Momentum equals mass times velocity. Velocity (in m/sec) Momentum Click to play The cannon ball has a smaller mass and a larger velocity. The cannon has a larger mass and a smaller velocity. However, since the system started with a net momentum of zero, the momentums of the objects afterwards must be equal and opposite to cancel each other out, = 0. Forces • A force is a push or pull that one body exerts on another. Force is measured in Newtons (N). • Forces can add and subtract. Total Net Force = +65 -15 = 50 N 10 kg 15 N 65 N Left is negative. Right is positive. Newton’s Laws of Motion: 1. An object in motion will stay in motion unless a force acts upon it. (Law of Inertia). If an object is at rest, it will stay at rest until acted upon. *Why we need seatbelts. 2. Force = mass x acceleration *Why a bowling ball does not go as fast as a ping pong ball when the same force is applied. 3. For every action there is an equal and opposite reaction. *Why a rocket goes up when gasses push down. Inertia Inertia is the tendency to not change motion, and is dependent only on the object’s mass (measured in kilograms). - Newton’s First Law. Object’s with more mass have more inertia and are harder to push. Object’s with less mass have less inertia and are easier to push. Frequent Equations from the Formula Sheet Solving Physics Problems: 1. Identify what is being asked and underline or highlight it. 2. Find the appropriate formula and write it down in your test booklet. 3. Plug in the known information (WRITE IT OUT). 4. Solve for the unknown. Lets Practice the Steps Together… • What is the approximate difference in gravitational potential energy of a 2kg object 3m off the ground and a 2kg object 1m off the ground? • • • • F) 19J G) 39 J H) 59 J J) 79 J First Situation PE=mgh PE=(2)(9.8)(3) PE= 58.8 J Second Situation PE=mgh PE=(2)(9.8)(1) PE= 19.6 J Difference Between= 58.8 – 19.6 = 39.2 J or approximately 39J = G The illustration above shows a student about to throw a ball while standing on a skateboard. Which illustration below correctly shows the skateboard’s direction of motion after the student releases the ball? A B C D • A cyclist moves at a constant speed of 5 m/s. If the cyclist does not accelerate during the next 20 seconds, he will travel — • • • • A0m B4m C 50 m D 100 m They are asking for distance and giving us speed and time. S=d/t 5=d/20 (Multiply by 20 on each side of the equal sign.) 20 x 5= 100m = D • How much work is performed when a 50 kg crate is pushed 15 m with a force of 20 N? • • • • Watch out for extra information! F 300 J G 750 J H 1,000 J J 15,000 J W=Fd W= (20)(15) W= 300 J = F Levers Which lever arrangement requires the least effort force to raise a 500 N resistance? A mechanic used a hydraulic lift to raise a 12,054 N car 1.89 m above the floor of a garage. It took 4.75 s to raise the car. What was the power output of the lift? • • • • A) 489 W B) 1815 W C) 4796 W D) 30,294 W This is a two part calculation. You’re looking for Power, but must have work before you can solve (P=w/t) 1. Calculate work: 2. Calculate power: w=fd P=w/t w=(12054)(1.89) p=(22,782.06) w=22,782.06 (4.75) P=4796.22 W We know it’s a force because it’s measured in Newtons! • A ball moving at 30 m/s has a momentum of 15 kg·m/s. The mass of the ball is — • • • • A 45 kg B 15 kg C 2.0 kg D 0.5 kg Momentum = mass x velocity P=mv 15=m(30) Divide by thirty on both sides. 15/30= 0.5 kg = D