:D Always eat your vegi-tab-le-s.
Sunday, November 21, 2010
Veggies Galore!
Okay so it may have been a while since Mr. Harrelson announced it, but he's gone vegetarian! In honor of this monumental event "Tree Frog Science" has a new Veggie background for a whole week!
Wednesday, November 17, 2010
Objective 1: Temperature, Thermal Energy and Heat
1. What are the three common temperature scales? Kelvin, Celsius (Centigrade), and Fahrenheit
. 2. How is the thermal energy related to temperature and heat? Thermal energy is the movement of the particles in a substance, temperature is the measure of heat and heat is the transferring of energy from one substance to another by conduction, radiation, and convection.
3. What does having a high specific heat mean? It is the amount of heat that it takes to raise a certain amount of the given substance's temperature by one degree.
4. Why does an ice cube melt in your hand? Your hand transfer's some of it's heat onto/into the ice cube, so it melts.
5. Why do some materials get hot more quickly than othe
rs? Because some substance's specific heat is lower or higher than others.
Objective 2: Scales
1. How do thermometers measure temperature? This liquid inside of a thermometer is colored alcohol (but it used to be mercury) and it is contained within a glass cylindrical tube. When it get heated up, both mercury and alcohol expand. Because of this the liquid in the cylindrical chamber must rise upwards. That is how a thermometer works. Click here for further info.
2. How are the three temperature scales alike? How are they different? To be honest this question confused me. I think Madeline answered it amazingly when she said: The three temperature scales, Fahrenheit, Celsius, and Kelvin, are similar because they all measure temperature. However they are different. Fahrenheit has the freezing po
Thank you Madeline! :)
3. Convert 5.0 C to Fahrenheit. 41 ^o Fahrenheit.
4. The surface temperature on the planet Venus can reach 860 F. Convert this temperature to degrees Celsius. 460^o C.
5. How much heat is required to raise the temp
erature of 5 kg’s of water by 10 K? 209,000 J.
Objective 3: The Transfer of Heat
1. What are the three forms of heat transfer? conduction, radiation, and convection
2. In what direction does heat move? up 3. How are conductors and insulators different?
Conductors
- transfers thermal energy well
- is a metal like silver and stainless steel
- is cold to the touch
- ionicly bonded
- doesn't transfer thermal energy well
- is covalently bonded
4. Would a copper pipe work better as a conductor or insulator?
Why do you think so? A conductor because it is a metal like silver and stainless steel, it is cold to the touch, and ionicly bonded.
5. Suppose you are camping on a mountain, and the air temperature is very cold. How would you keep warm? Would you build a fire or set up a tent? Write an explanation for each action you would take. Tell whether conduction, convection or radiation is involved with each heat transfer.
Suppose you are Harry Potter, Ron Weasly or Hermione Granger, and you are out and about looking for Horcruxes along the countryside and forests of Great Brittan and it's surrounding land. At the same time you are running away from Death Eaters in a magical tent. One day you are camped in Scotland (I know it's a while away from your destination, but deal with it, you have a wand) and it is COLD. So cold that you can remember a simple spell to clean the earwax from your purple-with-frostbite ears. :) So you have to act like a Muggle and somehow get on to the internet where you find a website (or blog such as this one) where an 8th grade science teacher has asked his American students a simple question:
The air temperature is very cold, how would you keep warm?
Then you read the student's answer, "First I would create a shelter to protect me from the cold, this would be conduction energy because the tent and it's blankets within would transfer their heat to me without moving. Then I would light a fire (outside the tent) this would be an example of radiation because the fire would be radiating heat by means on electro-magnetic energy. Then I would get up and do a few jumping jacks to get my blood pumping and heat me up furthermore. This would be an example of convection because I'd be moving around." Then you would close the internet page and chuckle about the Muggle's small viewpoint on the world, you'd then set up your tent, light a fire with your wand, do a few jumping jacks; then finally remember the spell that removes earwax. Then you would sit down in your magical tent and sigh, silently thanking the 8th grader and her science teacher.
Objective 4: Thermal Energy and Matter
1. What causes matter to change state? Matter changes it's state when put under a certain amount of heat (specific heat), or a certain amount of heat is released.
2. What happens to a substance as thermal energy increases? It's temperature increases, possibly resulting in the matter changing states.
3. Why does the temperature of matter remain the s
ame while the matter changes state? Ok so from what I understand the temperature of a given piece of matter stays the same in a state change because the energy that would regularly change the temperature is then being used to convert the given matter's state. Now I'm going to try to give you an analogy that makes sense. So say that I decide to run a 5k. (Ha ha I'm putting those Xcountry skills to the test!) While running that 5k I get very tired, when normally at that point in the day I'm energetic and cheerful. This is like the bit about state change a temperature because I'm using the energy that would normally keep me at a normal state to do something that physically (and mentally) pushes my body.
Now please don't ask me how I made that connection or analogy, I have no clue.
4. What causes a solid to melt? A solid melts because
it has reached its specific heat. For ice that is 2,060J.
5. Why should you poke holes in a potato before baking it? Because a baked potato is like a sack of water, when put in the microwave the water vaporizes and expands. If you did not poke holes in your potato before you put in in the microwave it would explode because of the pressure built up inside of the potato under the radiation of the microwave.
Objective 5: Using Heat http://www.eia.doe.gov/kids/energy.cfm?page=about_forms_of_energy-forms <---Awesome helpful website, and it's .gov!!!!!! :D
<---1. How do heat engines use thermal energy? Well from my limited knowledge of engines the thermal energy is what powers the engine. No joke. You'd think that there was more to it (and their probably is) but what basically happens is: the pistons move form each other's force of upward movement. The pistons themselves are thrust upwards by the mini- explosions that gasoline makes when ignited beneath the engine.
2. How are internal combustion engines different from external combustion engines? How are they similar? Ok I'm going to be entirely honest: engines confuse me. With all of their valves and pistons and other stuff with names I forget. I'm also a very visual person, so it helps for me to see diagrams, and so far I've found one helpful diagram on the web. I'm sorry I'm rambling, but here's my best answer:
Two examples of interior and exterior combustion engines are a car and (steam) train. Inside a car you have and internal engine where the heat source is inside the machine. In a train you have the exact opposite kind of engine where the heat source is outside the machine. (Those are their differences.) Now their similarities are
A) they are both engines
and B) they both have a heat source that generates their energy.
3. Why do you think modern cars use internal rather than external combustion engines? If a car had an exterior combustion engine you'd have to shovel coal into it on your way to work every morning.
4. What changes of state occur in the refrigerant of a refrigerator? Firstly I think it is necessary to define the word refrigerant. The word refrigerant loosely defined as a liquid commonly used in cooling systems to keep them cool. The refrigerant inside a refrigerator moves in a cycle in which it evaporates into a gas, and then it condenses into a liquid.
5. If the compressor in a refrigerator stopped working, how would its failure affect the heat transfer cycle? Suddenly the cycle would be only in a gaseous state, which would stop it from cooling off the fridge's inside.
Objective 6: In Hot Water Lab----- See more in class tomorrow. (And in my lab notebook.)
Goal: Build a containter for a 355 mL aluminum can that keeps water hot.
Your container must: - minimize the loss of thermal energy from the hot water - be built from materials approved by Mr H - have insulation no thicker than 3 cm. - not use electricity or heating chemicals (hand warmers, etc)
With a group of classmates or yourself, brainstorm different materials that prevent heat loss. Write a plan for how you will test these materials. Include a list of things you will test when doing your tests. Test out your ideas to determine the best insulating materials. Keep a log of your results in your lab notebook. Then bring the device to class!
Wednesday, November 10, 2010
Objective 1: Measuring Matter
1. Why is mass more useful than weight for measuring matter? In my opinion mass is more useful than weight for measuring matter because you can exactly weigh a gas, but you can determine it's mass from the container it is in.
2. A plastic box is 15.3 cm long, 9.0 cm wide and 4.5 cm high. What is the volume? Include units. It is 619.65 cm^3
3. What is the unit of measurement for density? Density can be written as g/cm^3.
4. Please write the formula for finding density. Density is equal to M/V = Mass/Volume = g/cm^3.
5. What is the formula for finding volume? Volume's formula is lwh or in other words length times width times height.
Objective 2: Changes in Matter
1. What is the main difference between a physical change and a chemical change? To quote Wikipedia, "A physical change is any change not involving a change in the substance's chemical identity." So in other words the substance simply changes in something like mass or weight.
A chemical change is just about the exact opposite. In a chemical change you are dealing with chemical energy, which includes handling the bonds between atoms.
I hope that covers the basics for that question.
2. What are the four ways that chemical changes can occur? They can occur in a precipitate experiment, when the color changes, the smell changes and when the temperature changes.
3. What is the Law of Conservation of Mass? Who created the law? To quote Yahoo Answers "Mass cannot be created or destroyed." And it was created by the great Lavoisier. (I'm sorry I keep quoting sites and people, but sometimes it's hard to put these answers in a phrase of words that makes sense!)
4. How are temperature and thermal energy different? From what I've read here on the wonderful yet horrible internet the main difference is best expressed with two diagrams:
Hope you can read that! :)
5. Please give an example of an exothermic reaction and an endothermic reaction. Exothermic reactions are reactions that emit heat, while endothermic emit the opposite; cold particles. One example of an exothermic reaction is the digestive system; examples of an endothermic reactions are the hot/cold packs that just about everyone used at one in our life to treat a sports injury or pain.
Objective 3: Energy and Matter
1. What are some of the forms of energy related to changes in matter? Chemical and thermal are two. Chemical = the changing of an object's molecular structure, thus its matter changes while thermal energy could result in something such as ice cream literally changing states of matter.
2. A rolling bowling ball has kinetic energy. (As well as potential and a few others such as thermal [if it is rolling in the sun].)
3. A bowling ball sitting still has (mainly) potential energy.
4. What is electromagnetic energy? Electromagnetic energy is energy of radiation. "When Maxwell’s TV is on it emits low levels of radiation or electromagnetic energy. Electromagnetic energy is basically defined as one of the four “fundamental interactions of nature” to quote Wikipedia. Electromagnetic energy is the energy of radiation, and deals with electric and magnetic fields. Electromagnetic energy is the energy that holds the very bonds inside of atoms together. Without it Maxwell would cease to exist." (Taken from my test question from this week.)
5. What is the energy of electrons moving from one place to another? Please give an example. The energy of traveling electrons is electricity! When Maxwell turns on the TV he is presenting an example of electrical energy. (Taken from my test question from this week.)
Objective 4: State Changes
1. How does the thermal energy of particles at a warmer temperature compare to the thermal energy of particles at a cooler temperature? On a warm day the thermal energy from the sun heats the air particles and makes the them become very hyper, while when it is a cool day the particles are slower because they have less thermal energy generated by the sun. Note that thermal energy is measured (like temperature) in the average.
2. Why does ice cream melt on a warm summer day? Ice cream melts on a warm summer day because: solidified ice cream matter absorbs some of the air's thermal energy and its particles become a bit more "hyper." This causes the state of matter to change from a solid to a liquid in the heat, and if you observed it long enough as a puddle on the sidewalk, you'd see that it would then vaporize and become a gas.
3. What does the melting point of particles have to do with vibrating particles? Particles vibrate and are "hyper" when they have melted and then vaporized, becoming gases.
4. When does condensation occur? Condensation occurs when the air particles on the outside of a glass are cooler than the substance within the glass (or vice versa); this creates water droplets to form on the outside of the glass.
5. Sublimation results under which conditions? If the triple point pressure is higher than atmospheric, then it is solid ---> gas. If the triple poiint pressure is less than atmospheric
pressure, then the reaction is solid ---> liquid ---> gas.
Objective 5: Boyle’s Law (Click Here for More Info)
1. What relationship is described by Boyle’s Law? Boyle's law states that when pressure increases, volume decreases; when volume increases pressure decreases. I look at it like a giant see-saw, with P on one side and V on the other. When one goes up in the air the other has no choice but to fall to earth. This law is called an inverse relationship.
2. Why do scientists only HALF fill high-altitude balloons? Scientists fill atomospheric balloons only half way because when they go farther up in the atomosphere the presure on the inside of the ballon increases. If scientists were to fill them up all the way- they'd pop before they gathered any information.
See my Friday the 12th test for further details on why they expand.
3. What is the formula for Boyle’s Law? Boyle's formula is: PV=K.
4. How does Boyle’s Law apply to physicians? One example of this applying to physicians is when they take blood pressure. We've all had them do it to us once or twice - so we all know what happens. They put a cuff on your arm and squeeze the pump- expanding the volume of the cuff and applying a greater amount of presure to your arm. So as the volume of the cuff goes up the amount of preasure on your arm goes up and vice versa.
5. SCUBA divers rely on Boyle’s Law for what purposes? As SACUBA divers (like my dad!) go father under water the amount of preasure on them increases. It is important for them to have commpressed air tanks because of this. The deeper they go the less "air" there is in their tanks. This is important because if they do not regulate and watch their "presure dials" carefully they could drown.
Objective 6: Charles’ Law (Click Here for More Info)
1. What is Charles’ Law? Charle's law states that when volume goes down, temperature goes down and the other way around.
2. As the temperature of a gas increases, the gas molecules move more quickly.
3. Who was the first person to fly in a hydrogen balloon? J.A.C. Charles of course.
4. What happened to Charles’ balloon after his first flight in 1783? When Charles's first hydrogen balloon took flight it stayed up in the air for about an hour- then landed about 15 miles from Paris where a group of terrified peasants attacked it. :D Isn't that a bit odd? They thought it was some kind of evil demon! Latter on King Louis XVI had to create a decree that explained to the peasants what the balloons were and NOT TO ATTACK THEM.
5. What factor is kept unchanged when demonstrating Charles’ Law? In Charles's law pressure must remain constant.
www.worldofteaching.com/powerpoints/chemistry/Charles_%20Law.ppt
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