[DKG]

Originally Posted by amit_purohit20

To understand Torque and rpm:

Torque = Force X Radius

The above equation doesnot contain rpm so torque and rpm are not dependent directly.

The above equation does not factor in the load either without which torque does not apply. RPM and the resultant angular momentum in my opinion play a role in affecting the resultant load a shaft experiences. That in turn determines how much torque is applied.

I see torque and angular momentum as one "generating" the other.

[DKG]

Amit your example of a block appears illogical.

You have said that it's a frictionless system

A block moving at 1m/s does not require any inputs from the hand. It will stay so indefinitely. The 10 N may have taken it from zero to 1m/s but once it reaches that speed even if the force is removed it will stay at 1m/s

Any force applied to a moving object (same direction) must necessarily accelerate the object. Be it the 10 or 20 N

If you say there is a physical limitation that the hand cannot move beyond 1m/s then clearly it cannot apply the 20N. For that matter it cannot apply the 10N either given the block is already moving at 1m/s

[DKG]

The torque applied by a open diff to a free wheel that is not rotating is determined by the moment of inertia the wheel has. Once the wheel starts spinning, in a frictionless system it applies a zero load back in the shaft and torque will be zero (frictionless system). Therefore the torque drops off in an open diff.

Now in real world scenario where there are friction losses and angular momentum is not conservable in a rotating wheel there is a quantum of torque needed to keep it spinning at the same rate.

As you rev more (incremental torque applied to once again counter the moment of inertia at the speed at which we rev more) the wheel spin is accelerated once again to a higher speed and the torque drops off. Torque is applied on a spinning wheel only when you are accelerating it. None of the torque you apply as you accelerate a free wheel is enough to budge the other wheel on the ground.

[VeyronSuperSprt]

How can you have a poll on a scientific fact?

You can have a poll on an opinion (such as which car do you feel should be the tbhp car of the year) which is why it is called an Opinion Poll.

You cannot have an opinion on a scientific fact as it does not convert a correct fact into an incorrect fact even if the majority voted wrongly.

It would only serve to show those with wrong opinions as ignorant and that is not a good thing (whereas if you have a different opinion on the tbhp car etc it does not show you in a bad light.)

In the interests of team-bhp, please delete the poll.

[Samurai]

This poll is not about the scientific fact. It is about how many people understand the scientific fact.

Read the poll question again, it says "Select all the statements that apply to you". You is the keyword here. We are not trying to decide science. Instead we are trying to figure out how many members understand it.

[VeyronSuperSprt]

Firstly, by stating that a wrong scientific fact applies to me, does in no way make the fact applicable to me. So if your objective is to know how many people have understood then the question should be rephrased as "Which of the statements do you think is right?" rather than asking which applies to you.

Secondly, how are you going to determine who is right and who is wrong? You have assumed that you have understood it correctly but what happens if your understanding is wrong? How will the stated objective of the poll be achieved in determining which members have understood it right?

As I said earlier, the majority voting for a wrong answer doesn't make it a right one.

[ampere]

Originally Posted by amit_purohit20

To understand Torque and rpm:
Torque = Force X Radius

The above equation doesnot contain rpm so torque and rpm are not dependent directly.

Torque can also be defined as I * Alpha. Where I is the Moment of Inertia of the Geometry and Alpha the Angular acceleration. So in other words as DKG mentioned torque can also be seen as rate of change of Angular Momentum.

When you say Torque = F X R, the F term has embedded in it rate of change of Momentum. And then the point from where its applied to where its effect is scene creates the angular momentum aspect.

[Samurai]

Originally Posted by VeyronSuperSprt

Firstly, by stating that a wrong scientific fact applies to me, does in no way make the fact applicable to me.

I agree. Fact won't change by voting against it. So that is not my intention at all.

Originally Posted by VeyronSuperSprt

So if your objective is to know how many people have understood then the question should be rephrased as "Which of the statements do you think is right?" rather than asking which applies to you.

You still haven't read the whole question (including the options), have you? The first two options are ascertaining whether the member has read the first 9 pages. Just to get a reference point.

Next 4 options are asking what the member believes to be right. Just like you wanted. You want me to add "I think" or " I beleive" to the last two options too?

Originally Posted by VeyronSuperSprt

Secondly, how are you going to determine who is right and who is wrong?

I am not going to give a verdict, I am not an expert in this field. I will leave it to the experts who can plainly see who is right.

Originally Posted by VeyronSuperSprt

You have assumed that you have understood it correctly but what happens if your understanding is wrong?

My understanding isn't important. Correct understanding is important. If I am on the wrong side and somebody proves it with scientific proof, I will jump ship in a moment.

Originally Posted by VeyronSuperSprt

How will the stated objective of the poll be achieved in determining which members have understood it right?

We both agree there is only one truth, right? This poll will determine how many people understand it. I could be on the wrong side, I'll risk that. I don't mind looking stupid in the pursuit of truth.

Originally Posted by VeyronSuperSprt

As I said earlier, the majority voting for a wrong answer doesn't make it a right one.

True.

[ex670c]

Hi Guys,

After all the scientific discussions I was very confused, so I decided to have a chat with a person, who professionally makes Gearboxes and drive's off-road, someone who can explain the most complicated of theories in the simplest of Language - Suresh Stephen.

My Question to him was -
Q1) How much torque will go to one wheel, with 3 locked differentials, with 3 wheels in the air?
Answer - 100% (excluding windage)

Q2) Why will the torque go to the one wheel.
Answer - For any WORK to be done there has to be a RESISTANCE the reason for the work being done, and to do the work you have to apply POWER

Now the question remains how much difference in torque will be there across and 4.5ft Axle Shaft? Since they are rotating at the same speed.

Similar Question for the Front Axle engagement in the Part-Time 4WD, where the Transmission Shaft is barely 12-15" Long, and Rotating at the same speed.

Regards,

Arka

[Samurai]

Great, so Suresh Stephen has also validated my understanding. Torque will go where there is resistance.

Arka, did you also ask him about the engine? Did he say whether engine can generate torque without load (resistance)?

[ex670c]

Originally Posted by Samurai

Torque will go where there is resistance.

Hi Sharath,

If Torque goes to where there is resistance?

Why Don't Open Differentials do Work, when one wheel is Lifted in the air?

Regards,

Arka

[tsk1979]

Originally Posted by ex670c

Hi Sharath,

If Torque goes to where there is resistance?

Why Don't Open Differentials do Work, when one wheel is Lifted in the air?

Regards,

Arka

Actually, Arka that statement is true if there is only one wheel.
What sharath meant to say "You can apply torque to increase speed or fight against resistance"

If you have open diff, it will transfer torque given by engine to wheel which is free.
So at rest, the torque will increase spinning speed of your free wheel. As RPMs increase, and rate of increase of RPM drops, less and less torque will be generated.

So with engine at 5000rpm, the torque will be low, rev limiter will cut off fuel, and only that much torque will be generated as to keep the free feel spinning at constant rate to counter drivline resistance.

you have to understand DIFF is a device which allows wheels to spin at different RPMs. The way it does that is that all engine power is transmitted to the wheel with lower resistance. So with one wheel free you get stuck.

Engine will initially generate torque and give torque to the freely spinning wheel increasing its RPM.

If you lock the diff, all the torque engine is capable of generating will go to the stuck wheel with traction.

[DKG]

Originally Posted by Samurai

whether engine can generate torque without load (resistance)?

Sharath if you were to simply take the quantum of air and fuel in an full intake stroke without compression and light it you won't get anything even remotely close to the explosion that occurs on full compression. We experience this daily at our kitchen stoves when we light it for cooking. Very mild explosion with negligible motive power. In other words without the load of compressed air your IC engine won't fire. So that is your first major resistance the engine deals with.

Then you have the resistance of the rings against cylinder walls and the crank inertial mass (include pistons, pins, con rods, bolts etc) plus the resistance of the crank bearings plus the flywheel inertial mass. All this is major resistance in an IC engine. Try turning a crank with your fingers you will know what I mean by load in an IC engine.

So what makes you think that there is no load in an IC engine prior to the flywheel? Without your initial compression load you have no engine !!

So to answer your question an engine develops torque because it internally is operating under load or resistance.

Now going back to my original question the fascinating relationship is between torque and angular momentum. All the torque generated at the crank gets stored as angular momentum in the flywheel. Everything else that follows in a drivetrain is like a brake to the flywheel, of course coupled with some torque multiplication via gears.

[ex670c]

Originally Posted by tsk1979

you have to understand DIFF is a device which allows wheels to spin at different RPMs. The way it does that is that all engine power is transmitted to the wheel with lower resistance. So with one wheel free you get stuck.

Hi Tanveer,

How does the Differential allow the wheels to spin and different RPMs?

How does the Differential transfer power to the Wheels?What happens inside the differential?

Regards,

Arka

[tsk1979]

Originally Posted by ex670c

Hi Tanveer,

How does the Differential allow the wheels to spin and different RPMs?

How does the Differential transfer power to the Wheels?What happens inside the differential?

Regards,

Arka

There are very nice videos on how differential works on youtube.
I think that is orthogonal to torque generation principle.

Your talk with the expert has actually answered the question perfectly!