Urgent !!! Physics Help.....Car Guys can come in here too!! Its related to both!

[mAdD INDIAN]

Ok I have a question here that relates to a question I have on my Physics assignment. (I'm not gonna post the original question because its too big and you need a diagram for it)

Anyway here's my question:: If the co-efficient of friction is greater, does that mean you have more traction or less traction to the ground?

Because the greater the weight over the drive wheels, the smaller the co-efficient of friction will be. Am I right on this? Therefore, the smaller the co-efficient of friction, the greater the traction?

Thanks...

 

[Soybomb]

To my understanding you have it opposite. A great coefficient of friction means better traction. A large drag coefficient of drag means you're driving an suv, etc

 

[FrogDog]

I'm thinking since
Force of Friction (Ff) = weight X coefficient of friction,
then the bigger the coeffient, the better the traction, and greater the Ff.

 

[Jumpem]

They're right the larger coefficient of friction means that you have more traction.

 

[Handle]

I'm not familiar with the exact definition of traction, but I do know that the force of friction increases as the coefficient of friction increases. Remember though that the coefficient of friction is really only a simplification of the complex interactions which occur between two surfaces in contact.

And for the second part, the weight over the wheels has nothing to do with the coefficient of friction. The coefficient of friction has to do with the two surfaces in contact. They are totally independent of each other.

 

[Thom]

Yes, the guys are right, you have it backwards.

More traction results from a higher coefficient of friction.

 

[Thom]

Oops, noticed second part. Coefficient from what i remember is a constant for any given surfaces. Ie, it is a multiplier.

ice will have a lower coefficient than, er, sandpaper, no matter what the weight on them.

 

[mAdD INDIAN]

I see.. thanks for correcting my mis-conception.

The part of the question that relates to this is "b) What is the smallest value of the co-efficient of static friction, that will prevent the wheels from slipping? Assume that each of the two drive wheels on the tractor bears 1/3 of the tractor's weight."

we don't have any values, just variables..this is a question that tests our understanding of physics.

So what would we do? This is what I did::
Fn on each wheel = 1/3mg
Fn on both wheels = 2/3mg

Ffriction = co-efficient * normal force
Ffriction = co-efficient * 2/3mg
co-efficient = 2Ffriction / 3mg

therefore, the greater hte mass, the smaller hte co-efficient?

 

[Handle]

Increased mass will increase friction but the coefficient of friction is independent of all other variables. It is a factor ONLY of the two surfaces in contact. Weight cannot change a coefficient of friction.

 

[FrogDog]

Coeffients of friction are just numbers that people assigned to certain surfaces. I don't believe they get manipulated by anything.

 

[CirekL]

umm... doesn't a tractor have 4 wheels?

 

[dcdomain]

I have a science question related to light and cars too...

Why do the wheels of a car look like it is spinning backwards when going at high speeds? I remember asking this in my 7th grade science class... the teacher didn't have an answer...

 

[mAdD INDIAN]

CirekL: yes..most tractors have 4 drive wheels but this question assumed that the tractor only had 3 drive wheels.

Btw, drive wheels mean wheels which have engine power applied to them.

So how would I solve this question? Anyone know?

 

[CirekL]

First question is, when I did high school physics regarding friction, we were always given an inclined slope. Is that the situation here? If so, you need to adjust your normal force to MG sin(angle of inclination) first. Frictional Force = (mu)N. And yes, the larger the coefficient, the more traction. I remember being asked the question, "so if I drive this nail through this board, and the board is now nailed to the table, does that mean the nail has a frictional coefficient of 1 with the board?"

 

[ManSnake]

I have a friend, his friend's friend's friend knows physics!

 

[mAdD INDIAN]

This question does not have any inclined platforms, we already had other questions which had that.

This one is quite tough, there are like 5 parts to it.

 

[Handle]

If the board is nailed to the table, then it is attached by an entity which can transmit both forces and moments.

 

[CirekL]

dcdomain: because the human eye can only perceive at 24-30 frames per second, so we see certain parts of the wheel making ALMOST 1 full rotation per frame, and it seems that it's really going backwards, but it's just going really really fast, usually in the thousands or RPMs, or hundreds of Revolutions per second.
You see it in the movies too beause the camera can only catch the wheel making almost a full rotation per frame. By full rotation, I don't mean 1, I just mean it doesn't end up where it started.

 

[Handle]

Then why do we see flicker on monitors at 60Hz?

 

[ApacheXMD]

madindian, can ya post the full question?

-patchy

 

[CirekL]

I personally like the theory of light and relativity. So if John threw the football to Sally faster than the speed of light, then the light bouncing off the football would get to Sally after the football smacks her in da grin!

 

[FrogDog]

<< I personally like the theory of light and relativity. So if John threw the football to Sally faster than the speed of light, then the light bouncing off the football would get to Sally after the football smacks her in da grin! >>



That's kind of a contradiction isn't it? Doesn't Einstein also state that nothing can go faster than the speed of light, which is why everything is 'relative' to it.

 

[CirekL]

Handle: Because sometimes a slow refresh rate means that we might observe faster than the monitor refreshes the whole image. And there's also a bigger timing gap between refreshing (depending on the type of monitor). It's also funny how we can observe contrasts, and relative motion. Put a fan in front of your monitor and you can see the lines being refreshed.
FrogDog: that's exactly why it's impossible for John to throw the football faster than the speed of light. He'd rip Sally's head off, and that just isn't acceptable. However, scientist have found the ability to warp... so instead of travelling faster than the speed of light, we can travel in directions we just can't see. i.e. rip in 3 dimension space continuum.
Get this, if you're on a bullet and shine a flashlight in both the foward and backward directions, the speed of light will still be the same relative to everything. So, the speed of light really isn't realitive to anything we know or see, actually, it's relative to magnetic fields that it generates.

 

[xtreme2k]

It is impossible to travel at speed of light or beyond it due to that fact that as you approach the speed of light, the mass of the object will increase to infinity. If the mass of the object is infinity, you will need infinity force to accelerate it to the speed of light. But we dont have infinity force, therefore we cannot accelerate an object to the speed of light.

 

[Handle]

CirekL: The problem is, the human eye does not perceive &quot;frames&quot; so to speak. We see fluid motion (motion blur... I won't get into it, don't have the time, plus I'm still weary from the arguments about motion blur and 3dfx and how it IS a good thing in theory) and it is certainly not at a fixed frames per second.