Multiple-Concept Example 1 discusses some of the physics principles that are used to solve this

Multiple-Concept Example 1 discusses some of the physics...

Key Concepts

Energy Conversion

Energy conversion involves translating between different units of energy and understanding how energy provided in one form, such as by gamma radiation, can be used to perform physical work like raising temperature or inducing phase changes. This conversion is fundamental when matching the characteristics of radiation (measured in absorbed dose) to the energy requirements of physical processes.

Absorbed Dose

This concept refers to the energy deposited by ionizing radiation per unit mass of material, usually measured in rads. It is essential in radiation physics for quantifying how much energy gamma rays impart to a substance, which directly affects the resulting temperature change or phase transition.

Latent Heat

Latent heat is the energy absorbed or released by a substance during a phase change at a constant temperature, such as melting (fusion) or boiling (vaporization). This concept is crucial when calculating the energy required to transition a substance like ice into liquid water and then into steam without a change in temperature during the phase change itself.

Specific Heat and Sensible Heat

Specific heat is the amount of energy needed to raise the temperature of a unit mass of a substance by one degree Celsius, and sensible heat is the energy responsible for changing the temperature of a substance without inducing a phase change. These concepts are important for determining the additional energy needed to heat a substance once it has undergone a phase change, or before a phase change begins.

Transcript

00:01 All right, question 50 states that multiple concept example one, as found on page 983, discusses some of the physics principles that are used to solve this problem.

00:11 So i recommend going through that problem first before looking at this one in your textbook, assuming you have.

00:18 The question here asks, what observed dose in rams of gamma rays is required to change a block of ice at zero degrees celsius into steam at 100 degrees celsius? so from ice to steam.

00:33 So in order for that to happen, we get to have this gamma resource, be applied to the ice long enough for it to turn into water.

00:44 And therefore, from water, turn that into steam.

00:47 So there's a bit of a process that has to go on here.

00:53 So if you remember when we're dealing with, i mean, in this case, radiation, but anything that turns, that causes a phase change in material, we'll need to look at a couple things, namely, if we go from a solid to a liquid, we'll have to incorporate in our answer, the latent form, latent heat of fusion from the solid to liquid, and from liquid to vapor, that process is known as a latent heat of vaporization.

01:24 Right, so the energy required for this needs to take these into account.

01:29 So if the question does state, what is the dose, absorb dose, applied to this block of ice, well, we know that those is just energy over mass, which may seem initially that we don't have enough information because you don't have the mass of the block of ice.

01:46 However, if we look at, again, the types of energy required to go into this, well, we see that to go from ice to water, that transformation, again, is called the latent heat fusion.

02:01 So that energy required is to overcome.

02:04 Needed to overcome this.

02:06 So that's given by the equation m times lf back in chapter 12.

02:12 And these values for lf and lv for water are also given in table 12 .3 in her textbook, but we'll get to that in a second.

02:25 So this first term goes from ice to water to change the temperature in water itself with no phase change present.

02:37 It's the expression mc delta t.

02:42 The one of you using, if we're saying, oh, with this dose, how much does the temperature change in a person, which we assume to be water? so this is within water, and then when it goes from water to steam, then we incorporate with the mass times the latent heat of vaporization.

02:59 So this whole term is over mass from above, in which we luckily don't need the mass of the block of ice.

03:10 So lf, we can find nearer textbook...

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