How much energy is generated by a federal warship?

Question

Hi! physics question! 10 points If ya' can awnser! How many joules of energy does a federal frigate (such as the U.S.S. Wabash http://www.unionnavy.org/img48.gif) have the potential to create?
The engine generates about 1000 horsepower and it is armed with 54 nine inch guns. If she was under full steam, the galley stove was on, and she fired all her guns at once, approximately how many joules of energy would this create?

Fine! If you physics people want to be like that, then how many joules of energy does it RELEASE?

Answer 1

Perhaps your URL reference has the needed info to work this, but I'm not going there. You can look up the necessary numbers if you've a mind to.

But, first, you gave us HP and power is energy over time P = E/t; so Pt = E the energy spent to move the ship. 1 HP ~ 745 J/sec; so you can figure the energy in Joules once you decide how long the ship will be steaming full. [See source.]

Second, what's the galley stove burning...wood, coal, gas, oil...what? Each material has a different heat of combustion; therefore, each expends energy at a different rate (MJ/kg).

Heat of Combustion
Fuel MJ/kg
Hydrogen 141.9
Gasoline 47
Diesel 45
Ethanol 29.8
Propane 49.9
Butane 49.2
Wood 15
Coal 15-27
Natural Gas ~54 [See source.]

And, of course, you failed to let us know how much fuel (kg) is being burned in that t time you've also failed to provide. For example, from above, if your ship burned one kg of wood in your time t, 15 MJ (mega joules) would be expended.

Finally, your cannons. As a WAG, since you've not provided the necessary info, I'm speculating the energy per mass rate of ordinary gunpowder (not high velocity, which was not available back in Wabash days) is less than that of gasoline, which is 47 MJ/kg, but greater than coal at 27 MJ/kg. So, let's WAG it at 30 MJ/kg.

Nine inch guns are big, but not nearly so big as the 16 inch guns on the WWII battleships, like the Iowa or Missouri. Each barrel of these guns could take a 1/2 ton of powder sacks...about 500 kg. The nine inchers are about half the size of the 16 inchers; so I'll WAG 250 kg of powder each. So each gun, based on these WAG's, would expend about 7,500 MJ per blast...you multiply this by 54 to get the total spent.

So there you are, fix a time t and the amount of fuel burned in that time t for the stove, and you can work the problem. Just add up the energy spent each for the engines, stove, and cannons.

Answer 2

Ha ha - good one. First of all, 1,000 hp for a warship?

C'mon - a railway locomotive has about 5,000 hp, and a frigate would have *much* more than that. I think you missed a few zeroes on this one.

The 54 nine inch guns is a hoot!. Where on earth would you put them all?

A frigate would be more likely to have two guns in the 3 to 5 inch range.

Thanks for the chuckles.

Answer 3

try again at least with the HP part.

Power is Joules / time, so for what interval of time are you wanting to add up the engine power to get the total Joules???

Answer 4

I admit I would fail this Q, I have no idea


Now why would you shoot a screen Worf?

Answer 5

zero. You can't "create" energy.