Need help with Physics! Please^_^

  • Thread starter lordroba
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lordroba

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ok, so i have this assingnment that i need to do for physics and i was wondering if some people could help me with it.

Basiicallly i need to decribe a project that a car engineer would be involved in, and how the concepts of forces(Newton's Law) apply to this project.

I also need to know what kind of educational background car engineers need to have, what kind of skills they need, their duties(maybe in previous positions too) and their salary expectations.

Another question is basically explain the physics behind ABS brakes.

I know this is not a really good thing to ask for, but i'm in a pinch and any help is greatly appreciated.

Thank you!
 
Tire design is an excellent example of how physics is applied to vehicle engineering. Just ask Ford SUV drivers.
 
Right now I'm designing a Formula SAE car here at school (oregon state university). I'm doing A Arms, which is a good example, I have to take the loading from the tires and figure out how it transfers into the suspension components, all of which is done with F=ma (although with a lot of forces and slightly complicated geometry). Once you've got forces figured out you can decide what size all of the a arm components need to be so they don't break.

Figuring out how much load transfer you are going to get under acceleration or braking is a good one too, and possibly something you could do yourself depending on how much physics you have taken.

By physics behind ABS, do you mean the physics of how ABS brakes function, or the physics of why you would want them? I could explain why they are good, but I honestly have no idea how the physical mechanism works :)
 
There's not much 'physics' to ABS is there? I mean, it's just a computer system... :confused:

I'd like to know their expected salary because I want to be an engineer :lol:
 
iceburns288
There's not much 'physics' to ABS is there? I mean, it's just a computer system... :confused:
Click to expand...

There's physics behind why you would want antilock brakes in the first place.

There's also physics in the system, first a computer sitting in a car can't decide what to do with the brakes unless it is getting data about what the car is doing, and a computer can't stop the car, a physical system has to do that.

For a high school physics class, why you would want antilock brakes would probably be more interesting.
 
The physics behind ABS brakes: A tire that is in a state of negative acceleration while rolling will transfer more negative-accelerative force to a car than a tire that is motionless and in a no-grip situation, sliding across the pavement. This is especially true in adverse conditions.

It's basically the same idea as "wheelspin hurts acceleration," but backwards.

If you didn't know already, ABS is a computer-controlled system that monitors wheel movement. If the system detects that a wheel has stopped rotating, yet the vehicle is still moving, the computer tells the brake on that wheel to let go, and then clamp again, and then let go, and then clamp again...(etc.)...very rapidly. If I'm not mistaken, ABS systems can be "confused" into thinking the car has simply stopped if all wheels lock up simultaneously. If that's true, I don't know if this has changed on modern systems...
 
Hi lordroba,

Good question on the ABS. The basic components are a rotary encoder on each wheel, and a device called a modulator (not moderator).

The modulator is a device which sits usually in the engine bay. The brake master cylinder(s) are connected to it, then the brake lines emerge from it and go to the wheels.

The encoders measure the individual wheel speeds, part of the ECU will then monitor the speeds. Older systems would look for wheels that became stationary whilst others were in motion whilst the brakes were active. Nowadays they also look at how quickly the wheels stop, as in did they immediately lock up or come to a progressive halt. This is how modern ABS works if all 4 wheels lock up.

In the situation above the ECU will activate a number of solenoid valves in the modulator. Typically one on each wheel's brake line for a decent system. This valve will apply and remove pressure from the brake line, activating and deactivating the brakes at hundreds of cycles per second.

There's not much F=ma in there, but it might be a good project.

And I apologise for the hideous modulator-moderator joke.

Kurtis.
 
Wolfe2x7
If I'm not mistaken, ABS systems can be "confused" into thinking the car has simply stopped if all wheels lock up simultaneously. If that's true, I don't know if this has changed on modern systems...
Click to expand...

I don't see how the system would know the difference between a car at standstill, and a car that is moving with all wheels locked, so that might be true. On the other hand, it's nigh on impossible to lock all four wheels simultaneously on a street car. (Icy roads exempt; ABS won't help you there anyway.)
 

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