Spirituality
30 Dec 11
14 Jan 12
1 edit
Originally posted by sonhouseI don't need any stupid comments from someone who does not have
It looks to me like you don't know that much about thermodynamics either, BTU is a unit of energy, HP is a unit of power, you have to state BTU per unit of time to get hp. So your problem is bollux.
a clue how to solve the problem. I gave enough information to solve
the problem. For your information Thermodynamics has to do with
energy, which has different forms. The ignition of the gas engine
produces energy that has 15 horsepower of force to lift the weight
a certain height. I did not ask how long it was going to take to lift
the weight, so no time is envolved. I asked how much gas is needed
to lift the weight a certain distance.
14 Jan 12
2 edits
Originally posted by RJHindsSo it doesn't matter if it takes one microsecond or one million years? I don't think that kind of problem would be acceptable on an SAT much less a college level physic course, considering one hp is 550 foot pounds/second. That specifies a time inherent in the problem.
I don't need any stupid comments from someone who does not have
a clue how to solve the problem. I gave enough information to solve
the problem. For your information Thermodynamics has to do with
energy, which has different forms. The ignition of the gas engine
produces energy that has 15 horsepower of force to lift the weight
a certain height. I d ...[text shortened]... so no time is envolved. I asked how much gas is needed
to lift the weight a certain distance.
14 Jan 12
Originally posted by sonhouseOkay, so you know the rate of time. But like I said, I am only asking
So it doesn't matter if it takes one microsecond or one million years? I don't think that kind of problem would be acceptable on an SAT much less a college level physic course, considering one hp is 550 foot pounds/second. That specifies a time inherent in the problem.
for the amount of gas needed.
14 Jan 12
Originally posted by sonhouseNo. That is way off. You have to know the following from Physics then
317 ft cubed. 190,200 odd btu. This is an arithmetic problem not a physics problem.
it is a simple problem to solve.
Total work input = useful work/efficiency
The mechanical equivalent of heat is numerically equal to the number of units
of mechanical work required to produce unit quanity of heat.
That is equal to 4.19 joules/cal = 3.09 ft-lb/cal = 778 ft-lb/BTU
14 Jan 12
Originally posted by RJHindsI'm looking at hp, 1 hp=550 ft/lb/sec.
No. That is way off. You have to know the following from Physics then
it is a simple problem to solve.
Total work input = useful work/efficiency
The mechanical equivalent of heat is numerically equal to the number of units
of mechanical work required to produce unit quanity of heat.
That is equal to 4.19 joules/cal = 3.09 ft-lb/cal = 778 ft-lb/BTU
So 15 hp can lift 8250 feet one foot in one second.
15 hp can lift 3000 pounds 2.75 feet in one second.
15 hp lifts 3000 pounds 60 feet in 21.8 seconds.
600 btu/3.4 = 176 watts. If it is 20% efficient, that one ft^3 gives 35.3 watts.
15 hp is 11190 watts continuously applied as long as it takes to do the total work.
316 ft^3 per second. missed that, so 316 X 21.8 seconds= 6910 ft^3.
14 Jan 12
2 edits
Originally posted by sonhouseHere is the Thermodynamics problem again.
I'm looking at hp, 1 hp=550 ft/lb/sec.
So 15 hp can lift 8250 feet one foot in one second.
15 hp can lift 3000 pounds 2.75 feet in one second.
15 hp lifts 3000 pounds 60 feet in 21.8 seconds.
600 btu/3.4 = 176 watts. If it is 20% efficient, that one ft^3 gives 35.3 watts.
15 hp is 11190 watts continuously applied as long as it takes to do the total work.
316 ft^3 per second. missed that, so 316 X 21.8 seconds= 6910 ft^3.
A crane is operated by a 15 hp gas engine. Taking into account the heat
lost by friction in the crane, THE EFFICIENCY OF THE ENGINE IS 20%. If
the combustion value of the gas is 600 BTU per cubic foot, how many
cubic feet of gas must be used to lift 3000 pounds through a height of
60 feet?
P.S. The following is from wikipedia article on BTU
One Btu is approximately:
1.054 to 1.060 kJ (kilojoules)
0.293071 W·h (watt hours)
252 to 253 cal (calories, or "little calories"😉
0.25 kcal (kilocalories, "large calories," or "food calories"😉
25 031 to 25 160 ft·pdl (foot-poundal)
778 to 782 ft·lbf (foot-pounds-force)
I gave you the value in my physics book (778 ft-lb/BTU)
One calorie is approximately 4.19 joules (not needed for problem)
15 Jan 12
Originally posted by RJHinds"energy that has 15 horsepower of force"
... the gas engine
produces energy that has 15 horsepower of force .. ...
so no time is envolved. .
mixing up 3 quantities (energy, power, force) in one sentence - what an idiot!
"no time involved" ??? why introduce power then? (Unit energy per unit time)
15 Jan 12
1 edit
Originally posted by wolfgang59Yep, I already said so in a post a few back.
"energy that has 15 horsepower of force"
mixing up 3 quantities (energy, power, force) in one sentence - what an idiot!
"no time involved" ??? why introduce power then? (Unit energy per unit time)
Originally posted by sonhouse
It looks to me like you don't know that much about thermodynamics either, BTU is a unit of energy, HP is a unit of power, you have to state BTU per unit of time to get hp. So your problem is bollux.
15 Jan 12
1 edit
Originally posted by wolfgang59I studied Physics for the purpose of engineering. And machines need
"energy that has 15 horsepower of force"
mixing up 3 quantities (energy, power, force) in one sentence - what an idiot!
"no time involved" ??? why introduce power then? (Unit energy per unit time)
to use fuel (gas) for energy to produce power and force to do work
for us. That is why it is all mixed up and the person challenged my
knowledge claiming to have a degree in Physics, so I challenged him
back with this simple thermodynamics problem to see how much he
really knew about it.
15 Jan 12
Originally posted by RJHindsBut you need to be vigorous with units if you want to make a valid problem.
I studied Physics for the purpose of engineering. And machines need
to use fuel (gas) for energy to produce power and force to do work
for us. That is why it is all mixed up and the person challenged my
knowledge claiming to have a degree in Physics, so I challenged him
back with this simple thermodynamics problem to see how much he
really knew about it.
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15 Jan 12
Originally posted by RJHindsRigorous is probably what he meant.
What do you mean? Vigorous with units?
Also joining the modern world and using SI units for science would be nice.
However you are all missing the point that the argument with evolution and
thermodynamics is all about the second law and entropy.
Entropy being a measure of information and of order and disorder.
The [bogus] argument against creationism being that disorder must always
increase, and that evolution contradicts this, and thus evolution must be wrong.
No amount of arguing about engineering problems about engine efficiency will deal
with this issue, because it's of absolutely no relevance to it.
RJHinds, you may well be very knowledgeable about engineering, and the physics of
engineering. However we are not dealing with engineering physics, we are talking about
information theory, and it's relationship to biology. Which you have demonstrated time and
time again you don't have the vaguest clue about.