A 75-kg human has a dose of 32.8 rad of radiation. How much energy is absorbed by the person's body? Compare this energy to the amount of energy absorbed by the person's body if he or she jumped from a chair to the floor (assume that the chair is 0.50 m from the ground and that all of the energy from the fall is absorbed by the person).

Video transcript

Hey everyone in this example, we have two parts in part a. We need to figure out the energy absorbed by 65 kg human exposed to 25.9 Reagan's of radiation. So we can interpret for part a these 25.9 residents in terms of 0.01 jewels of energy per kilogram of body tissue. We are then going to expand this and multiply by the weight given as 65 kg in the numerator. So this will allow us to cancel our units of kg, leaving us with our units of jewels for energy. And this is going to give us a results for part a equal to 16.835 jewels of energy absorbed. So this is going to be our first answer for part A. Now we can move on to Part B. Part B is asking the amount of energy absorbed by 65 kg human who jump from a stool with a height of 650.45 m to the floor, assuming that the entire force of the ball is taken in by the person sorry, of the fall is taken in by the person. So solving for part B. Here below, we are going to recall the falling formula where energy is equal to Faraday's constant times our distance. And when we take Faraday's constant times distance, we can say that this is also equivalent to the mass times gravity times distance. And so plugging in what we know, we can say that energy That is absorbed is equal to our mass given as 65 kg in the prompt. We're going to multiply this by our value for gravity which we recall is 9.8 meters per second squared. And then according to part B, our distance value is 0.45 m. So for our units we can go ahead and cancel out meters and what we're going to get here is a result equal to 286.65. We're left with units of actually we will not cancel out those units of meters because they are both in the numerator. So we actually will have units of kilograms times meters squared, divided by seconds squared. And we have meters squared because we have meters being multiplied by meters here, both in the numerator. So we should recognize that these units are equivalent to one Juul. So we can reinterpret this answer and say that we have 286.65 jewels of energy that is absorbed for part B. As our final answer for Part B. So now we can move on to Part C. Which asks us how the allowable or how the amount of energy in Part A differs from Part B. Now for part C. We want to recall that radiation is very ionizing and therefore is damaging yeah to human tissue and as we can see in part A we have energy that is a lower value compared to in part B, where our energy is a higher value. So we can say based on what we've outlined here, thus the allowable radiation exposures Arlo and for part B we have a higher energy because falling has we can say higher energy but it is not ionizing. So we have more energy in part B. Because we aren't exposed to any radiation as we are in part A. So to complete this example, we can just highlight for part C. This portion for our final answer. So I hope that everything I explained was clear. If you have any questions, just leave them down below and I will see everyone in the next practice video.