What is G-forces: Definition and 22 Discussions

The gravitational force equivalent, or, more commonly, g-force, is a measurement of the type of force per unit mass – typically acceleration – that causes a perception of weight, with a g-force of 1 g (not gram in mass measurement) equal to the conventional value of gravitational acceleration on Earth, g, of about 9.8 m/s2. Since g-forces indirectly produce weight, any g-force can be described as a "weight per unit mass" (see the synonym specific weight). When the g-force is produced by the surface of one object being pushed by the surface of another object, the reaction force to this push produces an equal and opposite weight for every unit of an object's mass. The types of forces involved are transmitted through objects by interior mechanical stresses. Gravitational acceleration (except certain electromagnetic force influences) is the cause of an object's acceleration in relation to free fall.The g-force experienced by an object is due to the vector sum of all non-gravitational and non-electromagnetic forces acting on an object's freedom to move. In practice, as noted, these are surface-contact forces between objects. Such forces cause stresses and strains on objects, since they must be transmitted from an object surface. Because of these strains, large g-forces may be destructive.
Gravity acting alone does not produce a g-force, even though g-forces are expressed in multiples of the free-fall acceleration of standard gravity. Thus, the standard gravitational force at the Earth's surface produces g-force only indirectly, as a result of resistance to it by mechanical forces. It is these mechanical forces that actually produce the g-force on a mass. For example, a force of 1 g on an object sitting on the Earth's surface is caused by the mechanical force exerted in the upward direction by the ground, keeping the object from going into free fall. The upward contact force from the ground ensures that an object at rest on the Earth's surface is accelerating relative to the free-fall condition. (Free fall is the path that the object would follow when falling freely toward the Earth's center). Stress inside the object is ensured from the fact that the ground contact forces are transmitted only from the point of contact with the ground.
Objects allowed to free-fall in an inertial trajectory under the influence of gravitation only feel no g-force, a condition known as zero-g (which means zero g-force). This is demonstrated by the "zero-g" conditions inside an elevator falling freely toward the Earth's center (in vacuum), or (to good approximation) conditions inside a spacecraft in Earth orbit. These are examples of coordinate acceleration (a change in velocity) without a sensation of weight. The experience of no g-force (zero-g), however it is produced, is synonymous with weightlessness.
In the absence of gravitational fields, or in directions at right angles to them, proper and coordinate accelerations are the same, and any coordinate acceleration must be produced by a corresponding g-force acceleration. An example here is a rocket in free space, in which simple changes in velocity are produced by the engines and produce g-forces on the rocket and passengers.

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  1. Gwen49

    I Generate a trackmap with speed and g forces

    Hello everyone, I hope you are all great. I am writing down to all of you concerning a problem of mine. I am struggling to generate a trackmap based on Speed (m/s) and G-Forces on excel. I followed a topic created 12 years ago but unfortunately it is closed ...
  2. W

    Trying to calculate G-Forces in LUA

    There's a game that I like to play that has planes and code, and collects things like angle of attack and speed. I was wondering how it'd be possible to get the rate of g-forces experienced within a climbing turn; I already understand from this thread...
  3. solarmidnightrose

    B Understanding G-Force: x,y and z Components Explained

    I've been to the amusement park recently, and one day I decided to use an app (Physics Toolbox), to collect some data. I downloaded the data, and it gave it to me in a .csv format. This table of data showed that there were x,y and z values for G-Force. I don't understand how G-Force has x,y...
  4. C

    B G-forces exposed during maximum perfomance Takeoff (Heli)

    Hello Folks I'd like to know if anyone of you guys know how to calculate the gforces in a glider (in this case helicopter) during maximum performance acceleration? Tonight I had a very serious discousion with a relative of mine who doubt that it's possible to accelerate from 0 to 140 kts within...
  5. M

    B Do Gravitational Slingshots cause G-forces

    Hi all, I am currently reading 'The Science of Interstellar' by Kip Thorne. Kip says that cooper could navigate around the Gagantua system using Gravitational Slingshots with Intermediate-Mass-Black-Holes. However these interactions would accelerate/decelerate the ranger by up to 22% of the...
  6. D

    Human capacity for G-forces, Energy calculation, and thrust

    I hope this is the right place for this... Question #1. How much can the human body stand multiple rapid G-force changes. Like let's say I made a vehicle that you could make sure all your body parts were 100% secured and it could move freely in space in any direction what would be the result of...
  7. A

    Physics - Human Tolerance to g-forces, acceleration limits, physiology

    Hi all, Does anyone know what physics limits human tolerance to extreme g-forces? I know the average human can take g-forces 5-7 g, and a fighter pilot, with training and a G-suit can maybe get up to 12 g. And people can survive g-forces higher than this for a very short time. I know all the...
  8. B

    How do I calculate g-forces on a roller coaster?

    Homework Statement I have constructed a small scale roller coaster for my physics class. I was given the task of finding a track design with a safe and enjoyable ride. For times sake I plan to simply calculate the changes in g-force. I am using a hotwheels car and plastic track. I simply need...
  9. C

    What's Happening on this Roller Coaster?

    Homework Statement The PDF graph shows the g-force values of a roller coaster at specific times during the ride. The normal g-force value during this assignment is -1 because the acceleration due to gravity on Earth is -10 m/s^2. We have to assign each time value from the PDF graph to...
  10. J

    G-Forces in Space and the Human Body

    Having an infuriating time trying to explain physics to co works. The debate is as follows: to get to Pluto in a quick time, say less than a year, you would have to travel extremely fast. If it were possible to reach such a speed via rockets/ion drive the human body would be crushed under the...
  11. A

    How to calculate g-forces on pilots in climbs, dives, outer space

    Hi all, I was working on same basic physics with calculate the apparent weight of a pilot in a turn. Let's have the plane be oriented such that the cockpit faces the sky, the belly faces the ground to start off with. Now, "Positive G-forces" are for a plane that begins to climb, or to put...
  12. I

    User_6Calculating G-Forces on Amusement Park Ride

    Hi, I'm trying to figure out the G-Forces a rider will experience whilst riding an amusement park ride. The track is 200m long and the 'pod' (What the rider is in) accelerates uniformly at a rate I found to be 5.1m/s2. So, to calculate the G-Force, I planned to use the formula g's = a /...
  13. B

    Proving Negative G-Forces with an Example

    Hi, nice forum. I was thinking how I would go about proving with an example, that negative Gs are occurring? Homework Statement Say a stunt pilot is doing a maneuver that will expose him to negative Gs. It could look like this...
  14. M

    Calculating Thrill Ride Velocity Using Potential and Kinetic Energy

    I have a question. Would it be possible to calculate the velocity of a thrill ride at any given time, given the rate of change in g-forces and the velocity of the ride at the start (or if there's a hill at the start, the velocity of the car going uphill)?
  15. O

    G-Forces on a Rollercoaster Ride: Exploring Centripetal Acceleration

    Homework Statement A rollercoaster car is going over a hill, with a person sitting with -no- restraints. The velocity of the car and radius of the hill are such that the centripetal acceleration of the cart is 15 m/s^2. What is the relative g environment (for the rider) and how many g's does...
  16. D

    Are G-forces smaller when traveling in space?

    Are G-forces smaller when traveling in space?
  17. G

    Proper acceleration and g-forces

    proper acceleration is the acceleration actually felt/experienced by an accelerating body. the integral of this gives the proper velocity. this makes intuitive sense. but the derivation of the formula for proper acceleration doesn't make intuitive sense to me. I'm very confused about how one...
  18. P

    Terminal velocity and g-forces

    Hi, I need a little help with my understanding of g-forces. From what I can gather, this "force" is the acceleration experienced by the object expressed as a multiple of g (the usual acceleration due to gravity). What has confused me, though, is the Wikipedia page, which says that "A...
  19. G

    What's the G-forces in a black hole event horizon?

    As the tile says, anyone's got an idea what the g-forces might be at the boundary of a black hole's event horizon? I got a formula to calculate the event horizon radius but not the the gravitational forces. Equivalence to Earth G's would be nice or in m/s2 = meter per second squared! Is it...
  20. F

    Trouble understanding g-forces

    Im having a bit of trouble understanding g-forces. I get that you divide the forces acting upon an object by 9.8 to obtain the number of g's but does that include forces like force normal? I am also having trouble applying them in situations when acceleration is in different directions such as...
  21. M

    How many g-forces are experienced by this object

    Hello everyone. I know this may be a simple problem for some, however I am having a hard time figuring it out. I need to figure out how many g-forces are experienced when dropping a 210 pound (95.2kg) object a distance of 1.5 feet. Thus I can figure out how much that object "weighed" at the...
  22. W

    Spacecraft Maneuverability: G-Forces in Space?

    I was watching Star Wars and started to wonder. If a man were flying a spacecraft in space, would he be able to turn quickly and speed up quickly? Or would there still be a G force like in jets on earth? Kind of hard for me to explain it. I know that the jets now days can turn faster than the...