A g-force is a measure of acceleration. On Earth, the acceleration of gravity generally has a value of 9. Since this is just a different scale for measuring acceleration, it not only applies to gravity, but can be used to quantify any acceleration.
See also: What is a connected car. As mentioned, you can configure the Geotab telematics Device to produce immediate audible feedback in response to excessive driving behaviors such as harsh acceleration, harsh braking, and harsh cornering.
When setting up harsh driving rules in MyGeotab, adjusting the level of sensitivity will affect when feedback is given for a harsh driving event — either a beep or a spoken alert if you have GO TALK installed. A smaller number e. A larger number e. Moving the slider to the right increases the sensitivity of monitoring. A sports car can safely take a corner faster than a truck. For a table of the average g-force exertions for various vehicle classes, see the Geotab Product Guide.
We recommend starting in the middle of the specific vehicle class and adjusting from there based on your fleet objectives and the unique aspects of your fleet. For example, if you are seeing too many harsh driving events and you want to manage that, you might select a more sensitive setting. Similarly, to closely monitor an ambulance carrying an EMT and patients in the back, you would increase the sensitivity. On the other hand, for a box truck carrying paper towels, a lower sensitivity might be sufficient.
If we look at the three harsh driving rules, we can do some simple calculations to find out how fast a driver would need to take a corner or accelerate from a stop sign to break these rules. The harsh acceleration and harsh braking rules are really the same thing and measure how quickly you are speeding up or slowing down. The least sensitive setting in the default rule for acceleration is 0.
To get a better understanding of linear acceleration and g-forces, check out this handy Acceleration Calculator. Harsh cornering is a little trickier to both calculate and grasp intuitively. Any time you change velocity you are undergoing an acceleration.
In The Empire Strikes Back, the Falcon's jump to hyperspace throws Artoo across the deck and into the open engine pit. Perhaps some of Han's "special modifications" need a tune-up.
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But acceleration is technically any change in the velocity of an object: speeding up, slowing down, and changing direction are all types of acceleration. That's why, on a rollercoaster, you feel G forces when you round tight bends and are thrown against the side of your seat a change in direction as much as when you plunge from the heights accelerate or grind to a halt decelerate. You feel the thrill, but don't black out, because the coaster's creators designed it to be well within the G-force tolerance of the average person.
The amount of G forces that are tolerable differs by individual. But for all of us it depends on three factors: the direction in which the G forces are felt, the amount of G's involved, and how long those G's last. Roller coasters are precisely calibrated so average people can enjoy the spine-tingling effects of G forces and few of the ill effects. Depending on which way your body is oriented when it accelerates, you can feel G forces front-to-back, side-to-side, or head-to-toe.
Or, in each case, vice versa—for example, toe-to-head. Each of us can tolerate the two horizontal axes a lot better than the vertical, or head-toe, axis. Facing forward in his seat on that final run, Stapp felt front-to-back G forces as he accelerated and back-to-front G forces as he decelerated, and as we've seen, he endured well over 10 times the G's my daughter and I encountered in the glider.
But vertical forces are another matter, and it has everything to do with blood pressure. At sea level, or 1 G, we require 22 millimeters of mercury blood pressure to pump sufficient blood up the foot or so distance from our hearts to our brains. In 2 G's, we need twice that pressure, in 3 G's, three times, and so on. Most of us would pass out with head-to-toe G forces of just 4 or 5 because our hearts can't summon the necessary pressure.
Blood pools in our lower extremities, and our brains fail to get enough oxygen. Fighter pilots can handle greater head-to-toe G forces—up to 8 or 9 G's—and for longer periods by wearing anti-G suits. These specialized outfits use air bladders to constrict the legs and abdomen during high G's to keep blood in the upper body. Fighter pilots can further increase their G-tolerance by training in centrifuges, which create artificial G's, and by learning specialized breathing and muscle-tensing techniques.
All of us, fighter pilots included, can handle only far lower toe-to-head, or negative, G forces. Facing a mere -2 or -3 G's, many of us would lose consciousness as too much blood rushed to our heads. Spinning at high speed, NASA's G research centrifuge at California's Ames Research Center can simulate up to 20 times the normal force of gravity we feel at sea level.
Courtesy NASA. Magnitude and duration are as critical as direction. While John Stapp showed that people can withstand much higher G forces than had long been thought, there is a limit to what anyone can take. Princess Diana tragically proved that. Experts estimate that, in the car accident that killed her, the G forces on her chest were about 70 G's and G's on her head. That acceleration was enough to tear the pulmonary artery in her heart, an injury almost impossible to survive.
If Diana had been wearing a seatbelt, the G forces would have been in the neighborhood of 35 G's, and she may have lived. Diana's death notwithstanding, Stapp proved that people can often survive high G forces for very brief periods. We're all familiar with this to a certain degree.
According to a article in the journal Spine , the average sneeze creates G forces of 2. If you jump from three feet up and land stiff-legged, write the authors of the book Physics of the Body , you'll feel about G's momentarily.
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