Making heat (physics project)

[DBBABD]

i really need help with my physics project ..we have to take an item and make it 4 degrees hotter than it orignally was (room temp) but we can only make it hotter by using our own energy. for example we could rub a eraser on the carpet ..something like that..could someone please help:eek_big:

[Buffy]

What energy do you have to work with? Rubbing an eraser is using chemical energy from your muscles...can you think of anything else you have?

 

Getting warmer,

Buffy

[DBBABD]

we can use anything as long as its not a chemical reaction like when u do baking soda and vinigar..we have to make the object hotter using OUR OWN energy

[Buffy]

we have to make the object hotter using OUR OWN energy

Yep. So that's my question: what energy do you HAVE?

 

What are you doing in Pine Haven, :)

Buffy

[DBBABD]

oh the energy i have is like my body energy like if i lift weights im using my energy...i hope im helpin (lol)

[GAHD]

Ice cube in your armpit. problem solved.

[DBBABD]

(lol) that wouldnt get me an A

[Buffy]

Why not?

 

Sometimes the most obvious solution is the best one,

Buffy

[DBBABD]

idk?? i think i already asked that question...but if you could pleas give me some more ideas.....somethings kids in my class are doing is rubbing sandpaper and wood together,eraser and carpet, bending a fork etc.

[Buffy]

ALL of those things are a variation of "use chemical energy in muscles to create friction, producing heat". If you want to do the same thing that everyone else is doing, sure, just think up another way to rub two objects together.

 

What GAHD handed you on a silver platter though was a much more creative--albeit simpler--solution. You'd be the only one in the class to do it the easiest way that could be conceived. If your science teacher gives you a C for that, he's not a very good science teacher (I personally know a lot of them!)...

 

There *are* other solutions, so keep thinking about the question: what other kinds of energy do you *have* or how could you also apply muscular energy? There are other things you could apply the energy to, and you could get very Rube Goldberg if you wanted to....

 

Complexity for complexity's sake,

Buffy

[DBBABD]

thanx for the help ..but i didnt mean for it to be this complex when i said chemical i meant chemical as in and aucutal chemical ....we are not limited to using our body for anything.....if u do have anysuggestions on what 2 things being rubbed together will become hot i will be the happiest person in the world:D

[Buffy]

we have to take an item and make it 4 degrees hotter than it orignally was (room temp) but we can only make it hotter by using our own energy.

 

when i said chemical i meant chemical as in and aucutal chemical ....we are not limited to using our body for anything...

So now at least you've got me confused: so how does "only...by using our own energy" mean that you're "not limited to using our own body for anything?

 

What I'm trying to say is, if this is a physics problem (and it is a classic, which is why you're getting the Socratic Method here) then it looks like you're really missing the whole point of the exercise.

 

On the other hand, maybe your science teacher really is just asking you "what two substances when rubbed together produce the most heat from friction", although that's definitely not how you posed the question at the beginning!

...if u do have anysuggestions on what 2 things being rubbed together will become hot i will be the happiest person in the world:D

Friction is caused by rough surfaces sliding past one another without lubrication. The roughness can be on a scale going from microscopic (rubber) to macroscopic (sandpaper) and the main point is not having lubrication, although the more macroscopic the roughness, the harder it is to lubricate (a little water will kill an eraser's ability to do anything, although it would do nothing to a metal file). Lubricants also dissipate heat: another reason to avoid them.

 

The other aspect of this exercise is the ability to absorb and (to a certain extent, depends on how fast you get the thermometer probe onto the object and how fast it reacts) retain heat. SO metal absorbs and retains heat well, and you might want to use that as the object, wood isn't so good although rubber is better.

 

Good luck!

Buffy

[freeztar]

Do you mean at least 4 degrees hotter, or do you mean exactly 4 degrees hotter? I'm assuming it is the former.

 

Here's a few ideas:

-Purchase one of those flashlights with a crank on it. Make sure you get one that can charge a cellphone. As you crank the handle, your kinetic energy is transformed into electrical energy. As the battery charges it gets quite hot. Downside is that it may take a while.

-Bow drill! This is one technique that "primitive" people used/use to make fire. It involves three pieces of wood (not including bow) and actually requires lubrication. :) A quick wiki search should tell you more about how to make a kit. I've done it successfully many times (even in rain). The technique is a bit tough to get to actually produce flames, but you can definitely heat it way above 4 degrees with little effort and zero technique.

-There's always the simple approach of sticking nearly anything between your hands (or even just your hands) and rubbing them together quickly.

-Another simple approach (kind of akin to GAHD's idea) is to take something edible, but non-dissolvable, and put it in your mouth. Your body temp can be used other ways too. I know my shoes always get very hot after walking around for a little while.

-Or you could just "cheat" and get one of these: Fire-Piston :)

[CraigD]

The title of this thread is “making heat”, so I’m going to assume that merely “transferring heat” doesn’t satisfy the project’s requirements. Simple solutions such as raising the temperature of a glass thermometer from 21° C (room temperature) to 25° by gripping it in your about 35° (2° less than oral body temperature) hand, then, are out.

 

A very simple way to transform mechanical work into heat, using only your body’s own mechanical power, is to use a hand drill () with an ordinary metal bit to drill a hole into a bit of metal plate. Though I haven’t used a hand drill since the 1960s (in these days of inexpensive cordless power drills, few people do), I’ve painfully discovered on several occasions that a few seconds of drilling can heat a piece of steel way more than 4°!

 

The main challenge with doing this project with a drill and steel strip is likely to be getting a good thermometer reading. My best suggestion is to clamp an professional-quality metal cooking thermometer (one that can measure both low and high temperatures) to edge of the metal strip with a metal hose clamp. Of course, you’ll need something to hold the strip – a table-mounted vise is ideal, but vice-grip pliers will work too.

 

A trip to a hardware store (eg: Home Depot) and a kitchen store should find all the tools and parts needed.

 

The fun science part of this project would be to use a watch, a tension scale, and some math to calculate the drills power, and try to calculate how many turns of the drill’s crank are needed to heat the metal precisely 4°. Taking the project that extra step would, I expect, assure a student a good grade.