need some help please..

[Guest vanteal]

Few questions here that I just cant seem to find the answer to in my home school book...these are all true or false questions..

 

#1.true or false:Fuels containe potential energy? t/f

 

#2.Fuels,wind and moving water are Directly dependent on solar energy? t/f

 

#3When hear energy travels by conduction,Energy is transferred from molecule? t/f

 

#4.Wood is a good conductor? t/f

 

#5.when gas or liquid is heated,Its molecules move away from each other? t/f

 

#6.when heat energy travels by convection,energy is transferred by the circulation of heated material. t/f

 

#7 wood can transfer heat energy by convection? t/f

 

#8. Radiant energy produces heat energy when it strikes matter? t/f

 

#9 light rays are a form of radiant energy? t/f ...

 

thanks for your help...

[YT2095]

1. fuels are reducing agents and without the presence of Oxygen or Oxidising agents, they are quite inert. (true for your teacher though)

 

2. wind is dependant on solar energy yes, water movement is based on Gravity influence from the moon and sun (tidal).( you`ll be expected to say True) 

 

3. it has 3 basic modes of transfer, conduction, convection and radiation. Conduction is passing the rapid movement of one molecule to another.(True again) 

 

4. wood will not conduct, even at extreme voltages (it`s the water in it that will conduct and carbon molecules) it`s considered to be an "Insulator"

 

5. perfectly true.

 

6. yes also true, it`s a bit like conduction, but using for example AIR as the medium in which the molecular vibration is tranfered. (so True again)

 

7. not sure I understand the question? Burning wood can yes. (I refuse to answer this, the question`s to vague)

 

8. yes, heat and or electric energy. (true)

 

9. Light is high frequency electro magnetic radiation, your answer would be a definate yes (also True)

 

 

 

If I did your homework fork for you, then shame on you!

 

these answers I`ve given are ONLY to get you some help, NON of them are actualy the entire story, but I expect your teacher will be happy with most of it.

 

Question #7 I refuse to answer as the question makes no sense at all? so you`ll have to "Wing It" on that one

 

 

[Guest vanteal]

OK, maybe you did a little for me, but thats just 9 out of about 50-60 questions. There's always a few that I just dont get or understand or cannot find..And I usully just end up guessing on those, So I figured insted of guessing I can get some help here. And help improve my scores , And find out the real answers. So either way Im still learning...Thanks so much again.. Im sure Ill have more in a day or so.. I gotta crack down on this scince stuff..

[swansont]

YT2095 said in post #2 :

 

 

4. wood will not conduct, even at extreme voltages (it`s the water in it that will conduct and carbon molecules) it`s considered to be an "Insulator"

 

5. perfectly true.

 

 

I think the question dealt with heat, so a discussion of wood conducting electricity is off topic.

 

So, wood will conduct heat, but does so poorly.

 

for 5, (when gas or liquid is heated,Its molecules move away from each other?)

since it's not universally true, the answer has to be "false." The molecules' motion is random, not away from each other, and not all materials expand when the temperature is increased, so it's not even a general trend.

[YT2095]

if you look at the questions, you`ll note they are of BASIC physics level, sure I could have easily expounded upon these questions and left the guy totaly lost, but the answers given are what his teacher would expect within reason

if it`s a TRUE/FALSE situ, then you use best judgement according to the level of the question. nothing more

 

example number 4, is wood a good conductor, the answer`s NO, whether it be of electricity or heat (both often go hand in hand too, as a "trend"). most fire doors are made of wood!

 

as for Q:5 what was the level of the question? the answer would be YES, the molecules do get further appart (the bank of questions isn`t of the level of advanced or specifics here).

 

 

 

 

[Guest court1659]

hey theres some questions i just can't find answers to in my home school book. if anyone knows them, please e-mail me.

 

1. food and fuels are both forms of chemical energy. t/f?

2.violet is the longest wavelength of light visible to the human eye. t/f?

3.sound energy cannot pass through empty space. t/f?

4.sounds with a high pitch are vibrating at a high frequency. t/f?

[YT2095]

1. true

2. false it`s the shortest

3. true if the "empty space" is a vacuum

4. true

 

)

[Dave]

fyi, the longest wavelength of light is ~700nm (which is red).

[swansont]

fyi, the longest wavelength of light is ~700nm (which is red).

 

There's not an absolute cutoff, though, so the choice is somewhat arbitrary for saying what the visible range is. The eye efficiency looks sorta gaussian, but a lot of the time a linear scale is shown, rather than a log scale, which makes it look like the efficiency goes to zero at 400nm and 700nm. I've used lasers at 780 nm and could see diffuse reflections at low power (a few mW). I've also seen 852 nm light (a few hundred mW source) which made me realize that I wasn't wearing my laser goggles.

[YT2095]

the drop off is curved at either end of the spectrum, it`s NOT a fullstop.and so certain intensities even only a few MW outside of our "normal" veiwing is not unusual