This page documents an OPTIMADE Unit Definition. See https://schemas.optimade.org/ for more information.

**ID: https://schemas.optimade.org/defs/v1.2/units/si/1970/temporary/gal**

`gal`

**Unit name:** gal

**Latin symbol:** Gal

**Display symbol:** Gal

**Description:** A unit of acceleration equal to 1 centimeter per second squared (1 cm/s²), defined according to the 1967 SI units.

The gal unit appears in the International System of Units (SI), 1st ed. (1970) defined as "1 Gal = 1 cm/s² = 10⁻² m/s²" with the footnote "The gal is a special unit of acceleration employed in geodesy and geophysics to express acceleration due to gravity."

- The International System of Units (SI), 1st ed. (1970) categorizes the unit as "units in use temporarily".
- The International System of Units (SI), 7th ed. (1998) changes the categorisation to "derived CGS units with special names".
- The International System of Units (SI), 9th ed. (2019) moves the unit definition to the margin aside the table for Non-SI units accepted for use with the SI units. It is not clear how to interprete the categorization intended with this placement of the unit.

**Resources:**

- Definition in the International System of Units (SI), 1st Edition
- Wikipedia article describing the unit

**JSON definition:**

```
{
"$id": "https://schemas.optimade.org/defs/v1.2/units/si/1970/temporary/gal",
"$schema": "https://schemas.optimade.org/meta/v1.2/optimade/physical_unit_definition.json",
"title": "gal",
"symbol": "Gal",
"display-symbol": "Gal",
"description": "A unit of acceleration equal to 1 centimeter per second squared (1 cm/s\u00b2), defined according to the 1967 SI units.\n\nThe gal unit appears in the International System of Units (SI), 1st ed. (1970) defined as \"1 Gal = 1 cm/s\u00b2 = 10\u207b\u00b2 m/s\u00b2\" with the footnote \"The gal is a special unit of acceleration employed in geodesy and geophysics to express acceleration due to gravity.\"\n\n- The International System of Units (SI), 1st ed. (1970) categorizes the unit as \"units in use temporarily\".\n- The International System of Units (SI), 7th ed. (1998) changes the categorisation to \"derived CGS units with special names\".\n- The International System of Units (SI), 9th ed. (2019) moves the unit definition to the margin aside the table for Non-SI units accepted for use with the SI units.\n It is not clear how to interprete the categorization intended with this placement of the unit.",
"resources": [
{
"relation": "Definition in the International System of Units (SI), 1st Edition",
"resource-id": "https://www.bipm.org/en/publications/si-brochure"
},
{
"relation": "Wikipedia article describing the unit",
"resource-id": "https://en.wikipedia.org/wiki/Gal_(unit)"
}
],
"defining-relation": {
"base-units": [
{
"symbol": "m",
"id": "https://schemas.optimade.org/defs/v1.2/units/si/1960/base/metre"
},
{
"symbol": "s",
"id": "https://schemas.optimade.org/defs/v1.2/units/si/1967/base/second"
}
],
"base-units-expression": "m*s^-2",
"scale": {
"exponent": -2
}
},
"x-optimade-definition": {
"label": "gal_si_1970_temporary",
"kind": "unit",
"format": "1.2",
"version": "1.2.0",
"name": "gal"
}
}
```