What Is G-Force? How to Calculate G-Forces (2024)

On April 29, 2001, CART (Championship Auto Racing Teams) officials canceled a race at the Texas Motor Speedway because the drivers experienced dizziness after as few as 10 laps. The combination of high speeds and tight turns at Texas Motor Speedway can produce forces of almost 5 g in the turns.

At 5 g, a driver experiences a force equal to five times their weight. For instance, during a 5 g turn, there are 60 to 70 pounds (27 to 32 kg) of force pulling the driver's head to the side. Let's see how to calculate how many g a car pulls in a turn and how these Champ cars can stay on the track under so much force.

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Calculating the g-forces on the drivers is quite simple. We just need to know the radius of the turns and the speed of the cars. According to Texas Motor Speedway's Track Facts, the turns on the track have a radius of 750 feet (229 meters). During practice, the cars turned laps at around 230 miles per hour (370 kph).

When a car goes around a turn, it accelerates the whole time (this is why, when you make a turn in your own car, you feel a force pulling your body toward the outside of the car). The amount of acceleration is equal to the velocity of the car squared divided by the radius of the turn:

Let's run the numbers:

  • 230 mph is 337 feet per second (f/s).
  • (337 f/s)2 / 750 feet = approximately 151 f/s2.
  • The acceleration due to gravity (1 g) is 32 f/s2.
  • 151 / 32 = 4.74 g experienced by the drivers.
Banked Turns

How can the car stay on the track under this kind of force? It's because of the banked turns.

The Texas Motor Speedway has 24-degree banking in the turns. The banking doesn't affect how we calculate the g-forces on the driver, but without the banking, the cars could never go around such a tight turn at 230 mph.

If a Champ Car tried to make a flat turn at 230 mph, it would slide right off the track because it doesn't have enough traction. Traction is proportional to the weight on the tires (the more weight, the more traction).

Banking a turn allows some of the g-forces created in the turn to increase the weight on the tires, increasing the traction. To figure out what portion of the g-force gets adds weight to the tires, you multiply the g-forces by the sine of the banking degree.

So, with a 24-degree banking, 1.93 g adds weight to the wheels. In addition, a portion of the 1 g from Earth's gravity also puts some weight on the tires: 1 g x cos24° = 0.91 g. Together, 2.84 g (or 2.84 times the car's weight) push down on the car during the turn, helping it stick to the track.

Downforce

The car's aerodynamics also create significant downforce at 230 mph. On an airplane, the wings provide lift. A Champ Car has spoilers like upside-down wings, providing the opposite of lift: downforce. The downforce keeps the car glued to the track with a downward pressure provided by the front and rear wings, as well as by the body itself.

The amount of downforce is amazing — once the car is traveling at 200 mph (322 kph), there is enough downforce on the car that it could actually adhere itself to the ceiling of a tunnel and drive upside down! In a street-course race, the aerodynamics have enough suction to lift manhole covers — before the race, all of the manhole covers are welded down to prevent this from happening!

Between the downforce and the g-forces, well over four times the weight of the car holds the tires to the track when it goes around one of those 24-degree banked turns at 230 mph.

Final Thoughts

Drivers take an enormous amount of punishment on a track like this. This level of acceleration is higher than most people ever experience. Even the space shuttle only develops 3 g when it takes off. Even more impressive is how long these drivers tolerate this kind of force.

The Texas Motor Speedway is 1.5 miles (2.4 km) long: The front stretch is 2,250 feet (686 m) long, and the backstretch is 1,330 feet (405 m) long.

At 230 mph (337 f/s), the drivers take about 6.5 seconds to go down the front stretch, and then they are slammed by almost 5 g of force for the next 6.5 seconds as they go around the turn. It only takes about 4 seconds to make it down the backstretch before the next turn and another 6.5 seconds of almost 5 g.

If the planned 600-mile (966 km) race had taken place, the drivers would have gone back and forth between 5 and nearly zero g a total of 800 times.

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What Is G-Force? How to Calculate G-Forces (2024)

FAQs

What Is G-Force? How to Calculate G-Forces? ›

The g-force produced by any massive object can be calculated by using a formula derived from Isaac Newton's law of gravity: g = G m / r 2 . In this formula: g is the acceleration due to gravity, in m / s 2 .

How to calculate G-forces? ›

The g-force produced by any massive object can be calculated by using a formula derived from Isaac Newton's law of gravity: g = G m / r 2 . In this formula: g is the acceleration due to gravity, in m / s 2 .

What is the g-force explained? ›

A g-force is a measure of acceleration. 1G is the acceleration we feel due to the force of gravity. It's what keeps our feet firmly planted on the ground. Gravity is measured in metres per second squared, or m/s2. On Earth, the acceleration of gravity generally has a value of 9.806 m/s2 or 32.1740 f/s2.

What is the g-force at 70 mph? ›

A car hitting a barrier at 70 mph (112 kilometers/hr) generates 100Gs. The launch acceleration of an arrow from a bow is 215Gs. A golf club hitting a golf ball creates a whopping 5114Gs!

How fast is 10 g-force in mph? ›

If you could remain at 10g for an entire second - you'd be going at 220mph. In 3.5 seconds of sustained 10g acceleration you'd be going faster than the speed of sound.

How fast is 7 g's? ›

A '7g' acceleration is seven (7) times the one 'g' rate. In U.S. Customary Units the acceleration due to gravity is about 32.2. feet per second per second, often written a 32.2. ft/sec^2.

How many G's can a human take? ›

Most of us can withstand up to 4-6G. Fighter pilots can manage up to about 9G for a second or two. But sustained G-forces of even 6G would be fatal. Astronauts endure around 3G on lift-off, one G of which is Earth's own pull.

What is the highest G force a human has survived? ›

A witness said it was "absolutely inconceivable anybody could go that fast, then just stop, and survive." But Stapp did—in fact, he went on to live another 45 years, dying quietly at home in 1999 at the age of 89—and he experienced a record-breaking 46.2 G's.

What car pulls the most G's? ›

The Demon is officially capable of pulling 1.8 Gs. The driveline sees 11,164 pound-feet of firing gear torque, thus resulting in the massive amount of G force. For reference, that's slightly more than the Bugatti Veyron (1.55G), and more than half that of a space shuttle (3G).

What does G force do to your body? ›

For example, as significant downward G-forces are applied to the human body, blood is forced from the head to the lower extremities, quickly overwhelming the heart's capacity to pump it to the brain. On the other hand, extreme negative or upward G-forces force blood from the extremities up toward the head.

How many gs is 500 mph? ›

When you're traveling 500 mph straight and level, you're pulling ONE G — just like when you're sitting in your recliner in your living room.

How many gs is 100 mph? ›

100 mph is about 45 m/s, so the accelleration would be a little under 0.5g. 100 km/h is about 28 m/s, so the accelleration would be a little under 0.3g.

How many gs is 7000 mph? ›

None. G's, or “g-forces,” are a measurement of acceleration. 7000 mph is a speed. If you are moving at a constant speed, you are not accelerating, and thus you would feel no g-forces.

How many GS can a fighter jet pull? ›

Acceleration is described in units of the force called “Gs.” A pilot in a steep turn may experience forces of acceleration equivalent to many times the force of gravity. This is especially true in military fighter jets and high-performance, aerobatic aircraft where the acceleration forces may be as high as 9 Gs.

How many G force is Mach 3? ›

At Mach 3, an object is traveling three times the speed of sound. At this speed, the g-forces can vary depending on the maneuvering of the aircraft, but typically it's around 9 g's. This means the aircraft experiences a force 9 times that of gravity.

How is the value of g calculated? ›

In Newton's law of universal gravitation, the attractive force between two objects (F) is equal to G times the product of their masses (m1m2) divided by the square of the distance between them (r2); that is, F = Gm1m2/r2. The value of G is (6.6743 ± 0.00015) × 1011 m3 kg1 s2.

How much force is 1 g? ›

One g is the force per unit mass due to gravity at the Earth's surface and is the standard gravity (symbol: gn), defined as 9.80665 metres per second squared, or equivalently 9.80665 newtons of force per kilogram of mass.

How fast is 5 g-force in mph? ›

G is a measure of acceleration due to gravity. On Earth it is 9.8 m/s/s (9.8 metres per second every second). 5G is 5 times this, so 49m/s/s. Which is 109.6 mph per second.

How do you calculate gravity g? ›

g = GM/R²
  1. Mass (M) lb. To enter exponents, use the e notation (for example, 3e24 = 3×10²⁴).
  2. Radius (R) mi. This is the distance between the centers of objects.
  3. Acceleration due to gravity (g) ft/s²
Jul 1, 2024

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