What Does 8.9876e+3 Joules Mean?

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In summary, the conversation discusses the energy yield of an average human cell when annihilated, which is calculated to be 8.9876e+3 joules. The participants then try to determine the real-world significance of this figure, with one suggesting it is comparable to the energy of dropping objects such as a brick or a D battery. However, they also mention that this amount is only about 2 calories, similar to the energy stored in an AA battery. The conversation concludes with some suggestions for estimating potential energy changes and trying out different equations to better understand the concept of comparable energy.
  • #1
GrayBush
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Hey there, not sure if I am posting this in the right place, so I apologize if I am not.

So after some calculation I came up with an average human cell yielding
8.9876e+3 joules if annihilated.

But what does that figure mean in the real world? I suppose I am looking for an analogy here along with a more refined number. Is it equal to the energy of somebody dropping a brick or a D battery or...
 
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  • #2
http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy) should give you some idea of what's in the neighborhood. I'm not sure if you mean by "annihilation" that the cell is converted into its rest energy by [itex]E = mc^2[/itex] or some more subtle process.

But really, you should be able to figure out the potential energy changes from dropping objects by [itex]mgh[/itex] also, for a rough estimate. I figure a 100 kg man dropped from a height of 10 meters (about 3 stories) is in the same ballpark as far as the energy goes.

If you really want to blow your mind, though, you can see from wiki that this is only on the order of ~2 calories. Yes, calories from food. Or about the same energy as that stored in a AA battery.
 
  • #3
Yeah, it was resting energy figured using E=mc^2. Okay, so if translated into kinetic energy what would that (8.9876e+3 joules) be comparable to?
 
  • #4
GrayBush said:
Yeah, it was resting energy figured using E=mc^2. Okay, so if translated into kinetic energy what would that (8.9876e+3 joules) be comparable to?

Save yourself some grief and decide that if you're looking for "comparable", you'll be OK with +/- 20%... And think about 1e+4 joules instead of 8.9876e+3 joules because it's way less work and won't change the comparables.

Now you can try it in a few standard equations. For example:

Gravity at the surface of the earth: [itex]E=mgh[/itex]: 104J is what happens when you drop a 10kg weight from a height of 100 meters, or a 100kg weight from a height of 10 meters, or a 1000kg weight from a height of one meter.

Kinetic energy: [itex]E=\frac{1}{2}mv^{2}[/itex]: 104J is 200 kg moving at 10m/sec (imagine a horse running into you at full speed), or 2 kg moving at 100m/sec (a cannonball from an 18th century light cannon at long range), or 20 grams moving at 1000m/sec (a modern rifle bullet).
 
  • #5


I can provide some context and clarification for the value of 8.9876e+3 joules. First, let's break down what this notation means. The "e+3" indicates that the number is written in scientific notation, where the "e+3" represents the number of zeros that follow the first number. In this case, it means there are three zeros, so the number is actually 8,987,600 joules.

Now, what does this number mean in the real world? Joules (J) is a unit of energy, specifically the amount of energy required to exert a force of one newton through a distance of one meter. To put this into perspective, the average human cell contains around 10 trillion joules of energy, so 8,987,600 joules is a relatively small amount in comparison.

In terms of an analogy, it may help to think of 8,987,600 joules as the amount of energy needed to power a light bulb for about 25 minutes. It is also equivalent to the energy released by a small car traveling at a speed of 100 km/h for about 2 seconds.

Overall, 8,987,600 joules is a significant amount of energy, but it may not seem like much when compared to larger values. However, in the context of a human cell, it is a considerable amount of energy that plays a crucial role in our daily functions. I hope this helps to clarify the meaning and significance of 8.9876e+3 joules.
 

1. What is the meaning of "8.9876e+3 Joules"?

"8.9876e+3 Joules" is a notation used to represent the amount of energy in the unit of Joules. The "e+3" indicates that the number should be multiplied by 10 to the power of 3, making the value equal to 8,987.6 Joules.

2. How is 8.9876e+3 Joules different from 8,987.6 Joules?

They are essentially the same value, just represented in different notations. The "e+3" notation is commonly used in scientific and mathematical calculations to make large numbers more manageable to read.

3. Can you provide an example of when 8.9876e+3 Joules would be used?

8.9876e+3 Joules can be used to represent the amount of work or energy required to move an object with a mass of 1 kilogram at a speed of 300,000 meters per second.

4. How does 8.9876e+3 Joules relate to other units of energy?

8.9876e+3 Joules is equivalent to 8.9876 kilojoules (kJ) or 0.0089876 megajoules (MJ). It is also equal to 2.1378 kilocalories (kcal) or 8.9876 x 10^3 watt-hours (Wh).

5. Why is it important to use scientific notation like 8.9876e+3 Joules?

Using scientific notation allows for easier manipulation and comparison of large numbers in scientific calculations. It also helps to avoid confusion and errors when working with very small or large quantities.

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