|
|
Post by the light works on May 18, 2013 15:42:02 GMT
In the years I have been driving larger vehicles, I have come to wonder if trucks have sufficient mass to form a gravity well. It happens often enough to seem like it is all the time, that as I drive behind a car, the car is unable to accelerate; and sometimes even seems to be unable to maintain speed, and gradually slows down until it is traveling 10-15MPH under normal highway speed. this only seems to affect the car immediately in front of the truck. cars in the slow lane and cars ahead of the car in question seem to have no trouble pulling away from the truck.
|
|
|
|
Post by GTCGreg on May 18, 2013 20:22:19 GMT
If the truck is affecting the car, I would think it would be more an aerodynamic issue rather than gravity. It could also be a psychological effect of the car's driver seeing a large truck in his rearview mirror.
|
|
|
|
Post by the light works on May 18, 2013 21:17:11 GMT
I try not to get that close, but if I got close enough for an aerodynamic effect, I would think it would be a pressure wave.
I would suspect it might turn out to all be a matter of perception, but it leads to some "come on, my 20 ton truck can accelerate/corner faster than that" moments.
|
|
|
|
Post by srmarti on May 18, 2013 21:33:11 GMT
My guess is it would take the best equipment in the world to detect a gravitational effect if it's possible at all. I don't think it is. I'm pretty certain any a effect a driver could feel is aerodynamic, not gravitational. Or imaginary  |
|
|
|
Post by OziRiS on May 23, 2013 23:06:23 GMT
I remember in the Disco show "How the Universe Works" they once mentioned a specific mass an object has to reach before it gains its own gravitational field and starts drawing in material on its own. I don't remember exactly how much that is, but I'm pretty sure it's more than any truck I've ever heard of.
|
|
|
|
Post by GTCGreg on May 23, 2013 23:29:17 GMT
Well, it's easy enough to figure out. If you had a 20 ton truck and a 2 ton car, and they were 5 feet apart from center of gravity to center of gravity, which would mean they are almost touching, the force of attraction between them would be: 0.000000234 pounds of force. I don't think that's going to have a noticeable effect on slowing down the car. Here's a website that has a calculator where you can plug in the values and see for yourself. www.ajdesigner.com/phpgravity/newtons_law_gravity_equation_force.php |
|
|
|
Post by srmarti on May 23, 2013 23:36:16 GMT
Well, it's easy enough to figure out. If you had a 20 ton truck and a 2 ton car, and they were 5 feet apart from center of gravity to center of gravity, which would mean they are almost touching, the force of attraction between them would be: 0.000000234 pounds of force. I don't think that's going to have a noticeable effect on slowing down the car. Here's a website that has a calculator where you can plug in the values and see for yourself. www.ajdesigner.com/phpgravity/newtons_law_gravity_equation_force.phpSo my intuition was mostly right? Nifty link! |
|
|
|
Post by c64 on May 28, 2013 22:41:27 GMT
If the truck is affecting the car, I would think it would be more an aerodynamic issue rather than gravity. It could also be a psychological effect of the car's driver seeing a large truck in his rearview mirror. Worse than the "sleepers" are the "Synchronous drivers" which drive on a lane right next to you and speed up and slow down as you do denying you the ability to switch lanes. Most of them do that fully automatically, they don't intend to annoy you. You need to accelerate or brake relative hard to break the sync. And most annoying to any trucker are the "precision speedometer drivers" which make their speedometer point to the exact speed limit but all standard speedometers read a bit too much making the truck driver foaming with anger because his calibrated speedometer reads a few miles less - enough to waste a lot of miles during driving time, too less to pass them on the fast lane. And most of the time, your preplanned "sleep" spot can't be reached in time and the police reading out your speedometer card give you a ticket for driving too long between breaks! And they can even do that after 3 weeks! |
|
|
|
Post by the light works on May 29, 2013 0:48:38 GMT
If the truck is affecting the car, I would think it would be more an aerodynamic issue rather than gravity. It could also be a psychological effect of the car's driver seeing a large truck in his rearview mirror. Worse than the "sleepers" are the "Synchronous drivers" which drive on a lane right next to you and speed up and slow down as you do denying you the ability to switch lanes. Most of them do that fully automatically, they don't intend to annoy you. You need to accelerate or brake relative hard to break the sync. And most annoying to any trucker are the "precision speedometer drivers" which make their speedometer point to the exact speed limit but all standard speedometers read a bit too much making the truck driver foaming with anger because his calibrated speedometer reads a few miles less - enough to waste a lot of miles during driving time, too less to pass them on the fast lane. And most of the time, your preplanned "sleep" spot can't be reached in time and the police reading out your speedometer card give you a ticket for driving too long between breaks! And they can even do that after 3 weeks! no, the most annoying ones are the "thermostat" drivers, who will accelerate to about 2 MPH above the limit, and then gradually slow down to 2 MPH under the limit, and repeat ad nauseum. if you add slowing down halfway through corners, and at the bottom of upgrades, you've almost got the perfect bad driver (without getting dangerous) |
|
|
|
Post by srmarti on May 29, 2013 3:32:22 GMT
no, the most annoying ones are the "thermostat" drivers, who will accelerate to about 2 MPH above the limit, and then gradually slow down to 2 MPH under the limit, and repeat ad nauseum. if you add slowing down halfway through corners, and at the bottom of upgrades, you've almost got the perfect bad driver (without getting dangerous) I'm not sure you could even count on cruise control holding the speed tighter than that. Two things many seem to forget is they aren't the only ones on the road going somewhere and a highway is not a race track. |
|
|
|
Post by the light works on May 29, 2013 13:56:26 GMT
no, the most annoying ones are the "thermostat" drivers, who will accelerate to about 2 MPH above the limit, and then gradually slow down to 2 MPH under the limit, and repeat ad nauseum. if you add slowing down halfway through corners, and at the bottom of upgrades, you've almost got the perfect bad driver (without getting dangerous) I'm not sure you could even count on cruise control holding the speed tighter than that. Two things many seem to forget is they aren't the only ones on the road going somewhere and a highway is not a race track. mine does. in fact, there is about 4 MPH deviation between going up an upgrade and down a downgrade. my entire beef abour "thermostat drivers" is that you CAN'T use cruise control behind them, because you are always resetting it. |
|
|
|
Post by srmarti on May 29, 2013 17:00:09 GMT
I'm not sure you could even count on cruise control holding the speed tighter than that. Two things many seem to forget is they aren't the only ones on the road going somewhere and a highway is not a race track. mine does. in fact, there is about 4 MPH deviation between going up an upgrade and down a downgrade. my entire beef abour "thermostat drivers" is that you CAN'T use cruise control behind them, because you are always resetting it. OK yours just manages to hold +/- 2mph. different cars have different masses etc, so even if the have the same tolerance, the won't react EXACTLY the same. That's life and just a very minor issue when I consider what I normally encounter on the road. |
|
|
|
Post by the light works on May 30, 2013 0:30:12 GMT
mine does. in fact, there is about 4 MPH deviation between going up an upgrade and down a downgrade. my entire beef abour "thermostat drivers" is that you CAN'T use cruise control behind them, because you are always resetting it. OK yours just manages to hold +/- 2mph. different cars have different masses etc, so even if the have the same tolerance, the won't react EXACTLY the same. That's life and just a very minor issue when I consider what I normally encounter on the road. I once followed a guy for about thirty miles, both of us on cruise control. let me spell it out for you. I tried an experiment once. I stepped full throttle until I hit 60. then I took my foot off the throttle until I had coasted down to 50. I repeated the process, and I paced the "thermostat driver" perfectly. this is NOT people with wonky cruise controls, because it has no connection to times when cruise controls lag or when they allow the car to coast over the set point. |
|
|
|
Post by srmarti on May 30, 2013 0:42:08 GMT
OK yours just manages to hold +/- 2mph. different cars have different masses etc, so even if the have the same tolerance, the won't react EXACTLY the same. That's life and just a very minor issue when I consider what I normally encounter on the road. I once followed a guy for about thirty miles, both of us on cruise control. let me spell it out for you. I tried an experiment once. I stepped full throttle until I hit 60. then I took my foot off the throttle until I had coasted down to 50. I repeated the process, and I paced the "thermostat driver" perfectly. this is NOT people with wonky cruise controls, because it has no connection to times when cruise controls lag or when they allow the car to coast over the set point. That sounds like someone playing games with you. Not sure how this explains "thermostat driver" It sounds more like someone not using cruise control, but some with their foot on the gas and losing focus on maintaining a constant speed. |
|
|
|
Post by the light works on May 30, 2013 11:50:23 GMT
I once followed a guy for about thirty miles, both of us on cruise control. let me spell it out for you. I tried an experiment once. I stepped full throttle until I hit 60. then I took my foot off the throttle until I had coasted down to 50. I repeated the process, and I paced the "thermostat driver" perfectly. this is NOT people with wonky cruise controls, because it has no connection to times when cruise controls lag or when they allow the car to coast over the set point. That sounds like someone playing games with you. Not sure how this explains "thermostat driver" It sounds more like someone not using cruise control, but some with their foot on the gas and losing focus on maintaining a constant speed. you've never paid attention to how the thermostat in your house works, have you? if you set it at 65 degrees, it will have a temperature variance of 2- 10 degrees depending on the type of thermostat. then the temperature reaches the low point, it turns the heater on. when the temperature reaches the high point, it turns it back off. until you get to certain new types of heating system, there is no regulation; it is all or nothing. thermostat drivers do the same thing. they accelerate until they notice they are going too fast, then they coast until they notice they are going too slow. |
|
|
|
Post by the light works on May 30, 2013 12:38:29 GMT
since we have drifted to general velocity related griping, there are two other groups that annoy the heck out of people in heavy rigs:
those who go slowly when it is illegal to pass them, and then it's off to the races in passing zones.
those who ALWAYS drive 40 MPH. in heavy traffic on a two lane road, it may take MILES to get an opportunity to get around them, and then when you go through a town with a lower speed limit, you are stuck in a conundrum between speeding to stay in front or starting the process all over again.
|
|
|
|
Post by srmarti on May 30, 2013 13:57:46 GMT
That sounds like someone playing games with you. Not sure how this explains "thermostat driver" It sounds more like someone not using cruise control, but some with their foot on the gas and losing focus on maintaining a constant speed. you've never paid attention to how the thermostat in your house works, have you? if you set it at 65 degrees, it will have a temperature variance of 2- 10 degrees depending on the type of thermostat. then the temperature reaches the low point, it turns the heater on. when the temperature reaches the high point, it turns it back off. until you get to certain new types of heating system, there is no regulation; it is all or nothing. thermostat drivers do the same thing. they accelerate until they notice they are going too fast, then they coast until they notice they are going too slow. Well there's your problem. My thermostat holds within a degree of the set point. Sounds like you are describing a driver that NOT using cruise control. That makes the thermostat analogy confusing. |
|
|
|
Post by the light works on May 30, 2013 14:17:21 GMT
you've never paid attention to how the thermostat in your house works, have you? if you set it at 65 degrees, it will have a temperature variance of 2- 10 degrees depending on the type of thermostat. then the temperature reaches the low point, it turns the heater on. when the temperature reaches the high point, it turns it back off. until you get to certain new types of heating system, there is no regulation; it is all or nothing. thermostat drivers do the same thing. they accelerate until they notice they are going too fast, then they coast until they notice they are going too slow. Well there's your problem. My thermostat holds within a degree of the set point. Sounds like you are describing a driver that NOT using cruise control. That makes the thermostat analogy confusing. well, I DID coin the term back in the 80s. and yes, I am describing a driver who is not using cruise control. I would have thought that was obvious. |
|
|
|
Post by srmarti on May 30, 2013 14:33:07 GMT
Well there's your problem. My thermostat holds within a degree of the set point. Sounds like you are describing a driver that NOT using cruise control. That makes the thermostat analogy confusing. well, I DID coin the term back in the 80s. and yes, I am describing a driver who is not using cruise control. I would have thought that was obvious. Nope, not to me. It sounds quite the opposite. You set a thermostat and leave it there. You are describing someone constantly changing speed. The thermostat analogy would be two or more people fighting about the temperature and constantly fiddling with the setting or someone manually trying to maintain the temperature by turning the heater on and off. |
|
|
|
Post by OziRiS on May 30, 2013 18:14:09 GMT
Ever notice how some people just don't seem to get the rather basic physics (gravity 101) behind driving up inclines? They go along at the speed limit and then hit an incline but it never dawns on them to press the gaspedal a little harder, since they're now fighting gravity a little harder, so they lose speed while going up. On the other hand, they don't get it either when they're going the other way, so they're speeding whenever they go down hill.
Easily one of the most annoying things in traffic, because once you've observed this more than once from the same driver, you just know that the person behind the wheel is a complete dunce! I mean, how hard can it be? After all, gravity IS the first of the four major forces you learn about while still very young, so it can't be THAT much of a mystery why the car is slowing down!
|
|
