Recent content by manal950

1 gram of water @ 10Celsius + 1 calorie of heat =1 gram of water @... 1 gram of water @ 10Celsius + 1 calorie of heat =1 gram of water @... ? my answer is 11 due the defnition of calorie

Ok 1 - 0.8 = 0.2 this answer for what ?

But is that formul for a and b correct ?

Hi Here is a question with answer can please check my answers http://store2.up-00.com/2013-11/1384723924451.jpg

sorry = 0.025 X 120 / 0.597 = 5.04

Suppose a human could live for two hours (120 minutes ) unclothes in air at 45 F . How long could he live in water at 45 F ? how do the thermal conductivities of water and air compare ? Air : k = 0.0251 W/mC , water = k = 0.597 W/mC my answer now for conduction we will say that...

yes now I got it .. thanks so so muck gneill

thanks so much but you said that is for Boltzmann's constant but here in this quetions we used 5.67 X 10 ^ -8 fro emissivy ? why ?

thanks but: 1 ) this value 5.67 X 10 ^ -8 for what ? becuse some time we used this for emissivy and some stme for stefan boltoman constant 2 ) Is alwyes in this formula we used surface area of the pipe ? 3 ) what is surface area for plate and cycle ? 4 ) How we know here in this question...

ok and this value 5.6697 X 10^-8 for what ?

Here we have question with answer Could please explain to me the answer of this question ? and can explain to me why we don't use area 2pi . r^2 because we have pipe ? and how we can know this combined modes ? I mean conduction and radiation ? In addtion , As I know s = the...

It must to make temperature with power 4 ?

my question why in the answer we did not say ( ( 273 + 55)^4 ) not ( 273 + 55) without power 4

A radiator in a domestic heating system operates at a surface temperature of 55 C. Determine the rate at which it emits radiant heat per unit area if it behaves as a black body ? why we did not square the temperature I mean ( 273 + 55)^4 please I need your help

Hi A steel plate 2 cm thick is maintained at a temperature of 550 C at one face and 50 C on the other . The thermal conductivity of stainless stress at 300 C is 19.1 W/mK . Compute the heat transferred through the material per unit length ? Answer : - we have q = - k . A ...