B Question about real world examples of 2.7 megajoules

[ArmChairPhysicist]

Recently I decided to combine three of my favorite things, physics, machines that propel things, and videogames.

The game in question: Space engineers.

Machine in question: A device of my own creation that abuses the marvel of artificial gravity to accelerate a projectile at high speeds.

The physics? How much energy can one of my cannons deliver in the form of kinetic energy.

After building a small cannon for testing and dusting off my physics textbook I came up with these variables.

Mass of the projectile: 20 tons or 18143.695 kilograms.

Acceleration due to the gravitational forces I've enslaved: 1177.20 m/s^2

Total distance of acceleration: 125 meters.

After a bit more math I found that the final velocity of the slightly unrealistic 20 ton shell is 542.4942396 m/s.
If needed I can put a link to the thread I found my velocity from acceleration and distance work on.

Now using the lovely 1/2mv^2 I came to a kinetic energy of 2,669,844,719 j, or 2.7 mj.

Now here is my problem. My mathematically inclined brain says that's a lot. But physics brain is saying that's not all that much energy.
How much energy is 2.7 megajoules?
Is there any good real world examples of something with this kind of energy?
Many thanks in advance.

 

[ArmChairPhysicist]

More information about the device that wasn't pertinent to the question. What I constructed today is an infinitesimal launcher compared to some of my builds. Today's only utilized 120 generators in game. My biggest have used many thousands of generators, each outputting 9.81m/s^2 acceleration within their fields. One of these days I'll build one of these larger ones and do the math on their kinetic energy outputs. But this becomes tricky due to uneven acceleration fields along the "barrel" due to overlap of thousands of generators.

 

[fresh_42]

Is there any good real world examples of something with this kind of energy?

Such energies are often compared to "tons of TNT": (1 kg TNT = 4 MJ)
https://en.wikipedia.org/wiki/TNT_equivalent

The meteor of Chelyabinsk had more than 500 kilotons.

 

[phyzguy]

I think you mean 2.7 Gigajoules. 2.7 Megajoules isn't that much energy - it's about the amount of food energy in a cheeseburger (600 calories). For reference, 1 Kilowatt-Hour is 3.6 Megajoules.

 

[ArmChairPhysicist]

Evidently all of my school work has leaked out of my head while I slept, there was my mistake. I apparently can't differentiate between 2.7 million and 2.7 billion

 

[ArmChairPhysicist]

And to ask again, 2.7 gigajoules? Just how much better is that?

 

[hilbert2]

You could calculate how much water that energy can heat from room temperature to boiling point, by using the heat capacity $C_{H_2 O} \approx 4000$ JK^-1kg^-1.

 

[Adas Aulendil]

2.7Mj is energy of 1.4 tonne car speeding 150km/h. You have 2.7Gj so it's eneegy of about 1000 cars speeding fast on highway.

 

[hutchphd]

or Wimpy says 1000 cheeseburgers viz

cheeseburger (600 calories)

(Of course this is 600kcal in physics calories)

 

[Vanadium 50]

What an odd necropost.

But a food calorie is a kilocalorie. I stick of dynamite = 1 stick of butter = 1 MJ.

 

[hutchphd]

Didn't see that it was necro (blinded by the cheese)......

It suddenly strikes me that Nuclear Weapon Yield might sound less scary if reported in butter equivalent energy. I know I would rest easier.

 

[Vanadium 50]

A kiloton of butter would probably give you a heart attack too -just for a different reason.

 

[hutchphd]

I realize that part of my motivation for this unit of destructive power can be traced directly to the existence of the "The Butter Battle Book" by Dr. Seuss.

I presume it is still allowed in school libraries in some places

 

[russ_watters]

But a food calorie is a kilocalorie. I stick of dynamite = 1 stick of butter = 1 MJ.

Or 1 Fat Man = 88 million sticks of butter. Oof.

 

[Vanadium 50]

Fat Man

Called that for a reason.

 

[Drakkith]

Let's crank it up a notch.

1 foe = 10^44 J = 10^38 MJ = 10^34 tons of TNT = 10^28 megatons of TNT.
1 kilocalorie = 4,184 joules and a 113 g stick of butter has 810 kilocalories, or 3.389 MJ.
So 1 foe = roughly 3x10^37 sticks of butter.

I propose a new unit: 1 foebutter (fb) = 10^44 grams of butter = 4.728x10^43 MJ of energy.
Inconveniently, the megafoebutter is shortened to Mfb, possible causing confusion with @mfb. By mass, one mfb is much less than one Mfb, but I suspect the former has a greater words per minute (WPM) if their post count is any indication.

 

[Vanadium 50]

I've created a monster.