There is a cylindrical shape sweet potato with an initial uniform temperature of 25°C and it has an average diameter of 70 mm and length of 150 mm. Thermal conductivity and diffusivity of the sweet potato are 0.62 W/m · °C and 0.2 x 10-6 m2/s, respectively. It is to be cooled by refrigerated air at 1.8°C. The average heat transfer coefficient between the potato and the air is 25 W/m2 · °C. Determine how long it will take for the center temperature of the potato to drop to 5.5°C.

Explanation:

The given data is as follows.

    ,    d = 70 mm =

    k = 0.62 ,    

    ,    v = 4 m/sec

       h = 25 ,  

First, we will calculate the value of as follows.

                    =

                    = 0.7056

Since, 0.7056 is greater than 0.1.

As,   = 0.159

                = 0.16

Also here,

              = 1.9

            = 1.9

                 T = 46.18 hrs

Thus, we can conclude that it will take 46.18 hrs for the center temperature of the potato to drop to .

labor day, patriot day, leaves start to change colors then fall from the tree

  1.the balanced   chemical equation is as below

cu +   2 ag(no)₃ → cu(no₃)₂   +2 ag

2.the   much silver   produced   is   50.9 g

step 1: find the   moles of cu

moles =   mass÷   molar mass

  from periodic table the molar mass of cu = 63.5 g/mol

moles is therefore = 15.00 g÷ 63.5 g/mol = 0.236   moles

step 2: use the mole ratio to determine the   moles of ag

from equation above   cu: ag   is 1: 2

therefore the moles of ag   =0.236   moles   x 2/1 =0.472   moles

step 3: find the mass   of ag

mass = moles x molar mass

from periodic table   the molar mass of ag =107.87 g/mol

mass   = 0.472   moles x 107.87 g/mol = 50.9 g

3.   the   much   silver   collected worth is   1.797 oz

  convert   50.9 g   to oz

that is   1 gram = 0.0353 oz

          50.9 grams =?   oz

by cross multiplication

={(50.9 grams x 0.0353 oz) / 1   gram}   =1.797 oz