# I Question about a g-force meter

1. Mar 6, 2016

### infiniteLoop

I few weeks ago I purchased a new Camaro with a Head's Up Display and among the data presented is a g-force meter. The meter does not show acceleration or deceleration; instead it is strictly lateral. Yesterday I entered a long and banked on-ramp to a freeway and the g-force meter reached 0.46g.

I realize one of the components of the equation for calculating a g-force number is speed. Note I said above the ramp is banked. All things being equal, had the ramp been flat and the same speed would the g-force meter show the same number?

Another question: like I mentioned above, there is no acceleration/deceleration reading - it is all lateral. Suppose, we take the same car to a place like Daytona or Talladega with high banked turns. Will the g-force reading still show? I've never driven on a race track with high banking, but would that not be a downward force rather than a lateral force acting on the car? Would the g-force meter still show a higher reading?

Thank you for your time and any insight into these questions...

2. Mar 6, 2016

### drvrm

how you say it is lateral?
well if your meter has GPS connectivity it can give you acceleration in all three directions-android g-force meters even give the plotted graphs -as to how your velocity /acceleration is changing.

3. Mar 6, 2016

### infiniteLoop

Lateral in the sense it gives a reading when turning. Not when accelerating or decelerating.

Screenshot from the owner's manual:

4. Mar 6, 2016

### A.T.

If "lateral" is relative to the car (as I suspect): no.
If "lateral" is always horizontal: yes.

5. Mar 6, 2016

### Staff: Mentor

So, that's really the question: does it measure the g-force parallel to the earth's surface or parallel to the car's horizontal axis? I would think it is parallel to the car's horizontal axis, since that is what determines if the car will skid through a turn.

6. Mar 6, 2016

### billy_joule

I'd agree.
It would be dangerous/misleading to do otherwise.

7. Mar 6, 2016

### rcgldr

You could try driving slow enough on the banked ramp to see if the lateral acceleration goes to zero or negative on the banked ramp.

8. Mar 6, 2016

### infiniteLoop

Thanks to all your replies. I appreciate it.

Indeed. I'll try the ramp at different speeds and see what happens. Unfortunately the gauge on the HUD is not accurate enough to go negative. It will just read zero.

OK - so here is a twist on my original question: I'm watching the NASCAR race from Las Vegas and the turns there are banked. Would the driver feel a lateral push across the horizontal plane in his seat, or would this be more like an aircraft and the load would be on his arse? I would speculate it would be both...

9. Mar 6, 2016

### rcgldr

I won't show negative, but it may show a positive value if the car is going slow enough that the banked turn is applying an "outwards" force on the car due to the slope.

If following a slow moving pace car, the drivers will feel the car exerting an "outwards" force on their bodies. If at racing speeds, the drivers feel the car exerting an "inwards" force on their bodies. There is a speed between pace and racing speeds where the drivers would only sense an "upwards" force from the car (a coordinated banked turn).

10. Mar 6, 2016

### infiniteLoop

Thank you! :)

And yes, the F1 gauge is much more sophisticated than the one in the production car. That one does measure acce/decel .

11. Mar 6, 2016

### rcgldr

If there is a parking lot with sideways sloped parking slots, and if the slope is sufficient, you may be able to get a non-zero reading from the lateral g-force meter while not moving. It depends on how the g-force meter is implemented.

Formula 1 race cars can sense acceleration and internal forces (like down force from wings, suspension loads) on all 3 axis (forwards / backwards, left / right, up / down).

12. Mar 6, 2016

### infiniteLoop

Interesting! I need to find what you describe. It would be interesting to take a picture of that. Hmmmm...