- #36
Arjun Singh
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So what would be mass of a body represented in let's say 10 kgs?wolf1728 said:You said
force=weight x acceleration
No.
force = MASS * acceleration
So what would be mass of a body represented in let's say 10 kgs?wolf1728 said:You said
force=weight x acceleration
No.
force = MASS * acceleration
10kgArjun Singh said:So what would be mass of a body represented in let's say 10 kgs?
I was going to give this answer a like, but then I decided it was the easiest question ever asked in the history of PhysicsForums.A.T. said:10kg
In tribute to this thread may I say that 10 kg is not its mass, that's its weight or an acquired downward force balanced by its center of gravity calculated by a pressure sensitive mechanical device, a resultant effect of Earth's gravitational field, atmospheric pressure and may we also add the effect of unseen matter or cosmic energy that may have variable effects on the interactive potential of a body of mass on different planets based on their precise location in the solar system. But to calculate an applied force on a body of weight 10 kg, weight would play the 'mass' unit. If I may say mass is actually the total volume of matter contained within a defined shape or body not including its planetary signatures. Am I right to some extent?russ_watters said:I was going to give this answer a like, but then I decided it was the easiest question ever asked in the history of PhysicsForums.
No. The kilogram is a unit of mass, not weight.Arjun Singh said:In tribute to this thread may I say that 10 kg is not its mass, that's its weight or an acquired downward force balanced by its center of gravity calculated by a pressure sensitive mechanical device, a resultant effect of Earth's gravitational field, atmospheric pressure and may we also add the effect of unseen matter or cosmic energy that may have variable effects on the interactive potential of a body of mass on different planets based on their precise location in the solar system. But to calculate an applied force on a body of weight 10 kg, weight would play the 'mass' unit. If I may say mass is actually the total volume of matter contained within a defined shape or body not including its planetary signatures. Am I right to some extent?
Then what is the unit of weight?russ_watters said:No. The kilogram is a unit of mass, not weight.
https://en.wikipedia.org/wiki/Kilogram
Newtons.Arjun Singh said:Then what is the unit of weight?
I assume you're talking about the power or thrust maximum ratings. Since the engine supplier doesn't know which propeller is going to be used, or other relevant variables, it's simpler in the case of propeller-driven aircraft to specify maximum rated power. The designer multiplies power by estimated propulsive efficiency to arrive at thrust available.Arjun Singh said:I was trying to understand various engine output comparisons between various aircrafts in an attempt to understand what factors affect the type of an engine selected for a specific aircraft.
True with jet engines. Piston engines and direct drive electric motors are often designed to provide lots of torque at low speed. A slow-turning propeller can produce thrust more efficiently.russ_watters said:Aircraft engines tend to need high rpm and low torque,
Confusingly, engineers often say mass when they mean weight. If a body is said to "weigh" 10 kg, it is understood colloquially to mean the amount of gravitational force the body would experience near the Earth's surface.Arjun Singh said:So what would be mass of a body represented in let's say 10 kgs?
So what is the road legal HP?CWatters said:Short answer no. Not in a road legal car.
Just for info.. Googke says Top fuel drag racers are running 11,000HP or just over 8MW. They burn 11 gallons a second so even the fuel pump is wicked.
Among road legal sports cars this one has a lot HP:Arjun Singh said:So what is the road legal HP?
A.T. said:Among road legal sports cars this one has a lot HP:
https://de.wikipedia.org/wiki/Bugatti_Chiron
I don't know about other types of vehicles though.
That's a cool car. Saying the obvious, a lot to depend on development of road networking suitable for high speed cars, for them to become production staples. Let's see how the progress happens. Currently the present public commute systems likes buse networks, need a serious upgrade in India for super cars to really get proper torquing opportunity :) Will do some research on cool public commute engines and share for comments.cjl said:There's no real legal limit, other than that it becomes increasingly difficult to meet any kind of emissions standards and reliability. That having been said, I bet you're thinking of the (claimed) 5000 horsepower Devel Sixteen. I'll be surprised if it ever actually happens though...
On road (Not race course) top speeds may accommodate maximum speeding of 150-200 mph in bursts, that too on specially built speedways, if I am not being conservative. So a 5000hp engine would run let's say on 10-15% output power on average using the momentum of the vehicle. No matter how powerful an engine is, there must be some scientific RPM limit for on-road driving right? I wonder what speeds would a 5,000 HP engine would extract in full throttle?cjl said:With that car, it's not a case of road infrastructure. It's that 5000hp is likely not possible in a way that would be either pleasant to drive or remotely reliable. It's not that hard for a modern engine to make 5000hp for a few seconds on a dyno, but it's a very different thing to make it so you can drive it 10,000 miles without a complete engine rebuild.
Are there any straight jet engines used these days? I thought they were more like Fan engines these daysruss_watters said:jet engines just move air.
Elaborate.sophiecentaur said:Are there any straight jet engines used these days? I thought they were more like Fan engines these days
- quieter and at least as efficient.
You just differentiated high bypass and low bypass jet engines right? If I am not mistaken 4th generation fighters are all working on turbojets. Is turbofan the 5th generation upgrade? Also turbofans are bulkier than turbojets ain't they?cjl said:Turbojet engines have 100% of the flow pass through the core of the engine, where it is heated (by burning fuel), just enough power is extracted to power the compressors, then it is passed through a nozzle to accelerate it out the rear of the engine. These are fairly low thrust and very inefficient until you get up to extremely high speeds, and I don't believe they're used at all any more even on things like jet fighters. Turbofans add additional turbines after the combustor to extract more energy from the core flow, and they use this to power a large front fan. This greatly increases thrust and efficiency at low speeds, at the cost of high speed performance. Since we aren't flying around at mach 2 all the time, this is a very worthwhile tradeoff. Even modern fighter jets use turbofans, but they use much smaller front fans with a much higher proportion still flowing through the core in order to keep the high speed performance acceptable.
Probably, but either way I consider that semantics. A turbo fan "just moves air" even if some is bypassed around the jet part. Does that make it similar to a turboprop or turbo shaft on a helicopter? Perhaps. Yes, the line between types of engines and naming conventions can be blurry.sophiecentaur said:Are there any straight jet engines used these days? I thought they were more like Fan engines these days
- quieter and at least as efficient.
All US 4th gen fighters (F14, 15, 16, and 18) run afterburning turbofans. It's true that they're bulkier than turbojets, but in jet fighters, they tend to run a pretty low bypass ratio which minimizes the extra bulk.Arjun Singh said:You just differentiated high bypass and low bypass jet engines right? If I am not mistaken 4th generation fighters are all working on turbojets. Is turbofan the 5th generation upgrade? Also turbofans are bulkier than turbojets ain't they?
The Wiki article sort of confirms how I remembered it. There is a massive difference between (most if no all) jet engines and rockets. A lot of the the thrust that's delivered comes from a 'fan' which makes it very little different from a propellor. A gas turbine can drive another mechanism (copter rotor or alternator) but that isn't relevant to this thread (I think).russ_watters said:Probably, but either way I consider that semantics. A turbo fan "just moves air" even if some is bypassed around the jet part. Does that make it similar to a turboprop or turbo shaft on a helicopter? Perhaps. Yes, the line between types of engines and naming conventions can be blurry.
cjl said:There's no real legal limit, other than that it becomes increasingly difficult to meet any kind of emissions standards and reliability. That having been said, I bet you're thinking of the (claimed) 5000 horsepower Devel Sixteen. I'll be surprised if it ever actually happens though...
Cool Helicopter.cosmik debris said:Tyres would be expensive. I've heard of US$20000 for tyres of some of the Supercars.
Cheers
cosmik debris said:Tyres would be expensive. I've heard of US$20000 for tyres of some of the Supercars.
Cheers
What makes a good tyre apart from the quality of rubber polymer used? I am a novice in this category and though this thread is for the discussion about aviation technology yet automobiles are quite similar.cjl said:Yeah, though there's really no reason why tires should be anything close to that. Pretty much any of the supercars should work fine on something like Michelin Cup2 or Pilot Sport 4S tires, which (in supercar-ish sizes) tend to run around $400-600 per tire.
So overall two primary components of tyre as a product. Material and Tread pattern, which as you say is specific to application. What I understand is, wet weather tyre would have different tread pattern from a hot weather tyre. Or a standard tarmac tyre would have different tread pattern from offroading type. Same between ones for high speed cars and regular cars. Also, vehicles with different center of gravity or weight or application will use tyres with different tread patterns. I am assuming that tyre material in all the mentioned categories can remain the same or with minor differences, right? And how do they differ in shape as all tyres are round and visible differ only in thickness?cjl said:There are a number of factors - the rubber compounds, the internal construction of the tire (materials used to reinforce both the sidewall and the tread area), the overall shape of the tire, the tread pattern that is cut into it, etc. There's also not one "best" design - it's heavily application specific.
cjl said:Yeah, though there's really no reason why tires should be anything close to that. Pretty much any of the supercars should work fine on something like Michelin Cup2 or Pilot Sport 4S tires, which (in supercar-ish sizes) tend to run around $400-600 per tire.
cosmik debris said:I agree, but in some countries, mine included, insurence and various certificates of fitness require the tyres to be speed rated at the top speed of the car regardless of whether you would actually drive that fast.
Cheers