# Starting with the basic units of length, mass, and time prove that 1 Gray=100 rads

1. Sep 17, 2008

### markm51

By definition, 1 Gray=1joule/kg of tissue and 1 rad=100 ergs/gm of tissue. Starting with basic units prove that 1 Gray=100rads

2. Sep 17, 2008

### markm51

1. The problem statement, all variables and given/known data
By Definition 1 Gray=1joule/kg of tissue and 100 rads=100 ergs/gm of tissue. Starting with the basic units of length, mass, and time prove that 1 Gray=100 rads

2. Relevant equations

3. The attempt at a solution

3. Sep 17, 2008

### mgb_phys

Re: Starting with the basic units of length, mass, and time prove that 1 Gray=100 rad

You would have to assume they are using the same model for tissue, but since the difference is only powers of 10 - I would say yes.
You just need to know how many joules in an erg and how many g in a kg (hint 1000!)

4. Sep 18, 2008

### bdforbes

Re: Starting with the basic units of length, mass, and time prove that 1 Gray=100 rad

How many ergs are in 1 joule? How many grams are in 1 kilogram?

Now if there are 100 ergs for every gram, how many ergs are there for every kilogram, keeping in mind that for every kilogram, there are 1000 grams? This will tell you that 100 rads = X ergs / kg.
If there are X ergs per kilogram, and each erg is equivalent to Y joules, then how many joules will there be per kilogram?

5. Sep 18, 2008

### vanesch

Staff Emeritus
Re: Starting with the basic units of length, mass, and time prove that 1 Gray=100 rad

That's not a part of the definition of the rad or the Gray. The definition is: *given* a certain (biological or other) material, the received dose of a certain radiation field *in that material* is the amount of energy deposited by the radiation in the material, per unit of mass of the receiving material.

Yup.

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