Help with this physics please

[Theslowone]

Crap sorry, here it is. I actually edited somehow and it created a new post, hell if i know.


An iron bar of length 67.7 cm and cross sectional area 23.7 square millimeters has a temperature difference of 56.0 degrees Celsius maintained between its ends. What is the rate, in watts, at which heat flows along the bar?

448 J/kg*C specific heat
.107 cal/g *C

w/m*C = 79.5

 

[chin311]

OMG you should liek make THREE threads about it.

 

[SaltBoy]

e=mc^2

Really.

 

[chin311]

no i think its:

2+2=5

 

[conjur]

Originally posted by: chin311
no i think its:

2+2=5

But only for very large values of 2!

 

[chin311]

Originally posted by: conjur

Originally posted by: chin311
no i think its:

2+2=5

But only for very large values of 2!

and small values of 5!

 

[DrPizza]

Simple!
You obviously asked 2 questions that are 180 degrees out of phase. Due to destructive interference, they've canceled each other out.

 

[DrPizza]

Originally posted by: chin311

Originally posted by: conjur

Originally posted by: chin311
no i think its:

2+2=5

But only for very large values of 2!

and small values of 5!

LMAO, I say that at least once a year while teaching my remedial math class... I just love to see the faces of those paying attention. 🙂

 

[dullard]

You are missing one important piece of data: the thermal conductivity of that iron bar. And to be really exact, it is a function of temperature... The answer is (use the average thermal conductivity over that temperature range as a simplification):

Power = (thermal conductivity) * (cross sectional area) * (Thermal Gradient) / (length)

Ok I see you edited the information into your first post:

"w/m*C = 79.5"

Power = 79.5 W/m°C * 23.7 mm^2 * 56.0°C / 67.7 cm = .156 W

 

[chin311]

LOL,

oh how fitting the threadstarter's nickname is, bahhahahahhaha :beer: