# Homework Help: Heat transfer TNT exercise

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1. Aug 14, 2016

### williamcarter

1. The problem statement, all variables and given/known data
I would really appreciate if you could give me some hints regarding what exactly to do at iv)

iv)

Given formulas:

2. Relevant equations
f(y)=(ro*R^5/E*t^2)

3. The attempt at a solution
we know that f(y)=0.75
1ton TNT=4.184*10^9 J
ro=1.003kg/m^3

We have the above formula:f(y)=(ro*R^5/E*t^2)
we have almost everything, but I do not know exactly how to approach this problem and what exactly to do with that table.I was thinking of doing the slope,

Last edited: Aug 14, 2016
2. Aug 14, 2016

### Staff: Mentor

The image attachment is missing.

3. Aug 14, 2016

### williamcarter

Ow,my bad, I will fix it, I don't know why it didn't upload maybe because format.

4. Aug 14, 2016

### Staff: Mentor

There are several possibilities:
1. Plot $R^5$ vs $t^2$ and determine the slope.

2. Take the log of both sides of the equation: $5 \log R = \log \frac{Ef}{\rho}+2 \log t$ or $$\log R = 0.2\log \frac{Ef}{\rho}+0.4 \log t$$
Use your graphics package (say Excel) to plot logR vs log t. The slope should be 0.4. Have your graphics package determine the equation of the best straight line. Find the value of R at 1 sec.

3. Calculate $R^5/t^2$ for all four data points, and take the average.

I would always choose item 2.

5. Aug 14, 2016

### williamcarter

Thank you, much appreciated !