# Acceleration Get the acceleration value (milli g-force) in one of three dimensions, or the combined force in all directions (x, y, and z). Find the acceleration of the @boardname@ (how fast it is speeding up or slowing down). ```sig input.acceleration(Dimension.X); ``` ## ~hint You measure acceleration with the **milli-g**, which is 1/1000 of a **g**. A **g** is as much acceleration as you get from Earth's gravity. ## ~ Watch this video to learn how the accelerometer on the @boardname@ works: https://www.youtube.com/watch?v=byngcwjO51U ## Parameters * **dimension**: the direction you are checking for acceleration, or the total strength of force. >`x`: acceleration in the left and right direction.<br/> `y`: acceleration in the forward and backward direction.<br/> `z`: acceleration in the up and down direction.<br/> `strength`: the resulting strength of acceleration from all three dimensions (directions). ### ~hint **Forces in space** Since we don't live on a flat world, forces happen in three dimensional space. If the movement of an object isn't exactly in the direction of one axis, we need a way to calculate its acceleration from the values measured for all the axes together. If you put your @boardname@ on a level table and push it diagonally, you have an acceleration in two dimensions. You can find the acceleration in that direction just like how you calculate the long side of a triangle using the two shorter sides (**X** and **Y**): ```strength2D = Math.sqrt((accelX * accelX) + (accelY * accelY))``` If you decide to lift your @boardname@ off the table, then you've just added another dimension, so insert the acceleration value for the **Z** axis into the equation: ```strength3D = Math.sqrt((accelX * accelX) + (accelY * accelY) + (accelZ * accelZ))``` This calculation is called the [Euclidean norm](https://en.wikipedia.org/wiki/Euclidean_norm) of acceleration. ### ~ ## Returns * a [number](/types/number) that means the amount of acceleration. When the @boardname@ is lying flat on a surface with the screen pointing up, `x` is `0`, `y` is `0`, `z` is `-1023`, and `strength` is `1023`. ## Example: bar chart This example shows the acceleration of the @boardname@ with a bar graph. ```blocks basic.forever(() => { led.plotBarGraph(input.acceleration(Dimension.X), 1023) }) ``` ### Example: quake meter Every 5 seconds, with the @boardname@ facing upward on a flat surface, show how much the earth is shaking (if at all). ```blocks basic.forever(() => { basic.showNumber(input.acceleration(Dimension.Strength)) basic.pause(5000) }) ``` ## See also [set accelerometer range](/reference/input/set-accelerometer-range), [compass heading](/reference/input/compass-heading), [light level](/reference/input/light-level)