# Signals and Units¶

Many commands allow you to specify arguments in terms of well-known physical quantities. This page gives an overview of each quantity and its unit.

## Time¶

## Angles and angular motion¶

### angle: deg¶

All angles are measured in degrees (deg). One full rotation corresponds to 360 degrees.

For example, the angle values of a `Motor`

or
the `GyroSensor`

are expressed in degrees.

### rotational speed: deg/s¶

Rotational speed, or *angular velocity* describes how fast something rotates,
expressed as the number of degrees per second (deg/s).

For example, the rotational speed values of a `Motor`

or the
`GyroSensor`

are expressed in degrees
per second.

While we recommend working with degrees per second in your programs, you can use the following table to convert between commonly used units.

deg/s | rpm | |

1 deg/s = | 1 | 1/6=0.167 |

1 rpm = | 6 | 1 |

### rotational acceleration: deg/s/s¶

Rotational acceleration, or *angular acceleration* describes how fast the
rotational speed changes. This is expressed as the change of the number of
degrees per second, during one second (deg/s/s). This is also commonly written
as \(deg/s^2\).

For example, you can adjust the rotational acceleration setting of a `Motor`

to change how smoothly or
how quickly it reaches the constant speed set point.

## Distance and linear motion¶

### distance: mm¶

Distances are expressed in millimeters (mm) whenever possible.

For example, the distance value of the `UltrasonicSensor`

is measured in millimeters.

While we recommend working with millimeters in your programs, you can use the following table to convert between commonly used units.

mm | cm | inch | |

1 mm = | 1 | 0.1 | 0.0394 |

1 cm = | 10 | 1 | 0.394 |

1 inch = | 25.4 | 2.54 | 1 |

### dimension: mm¶

Dimensions are expressed in millimeters (mm), just like distances.

For example, the diameter of a wheel is measured in millimeters.

### speed: mm/s¶

Linear speeds are expressed as millimeters per second (mm/s).

For example, the speed of a robotic vehicle is expressed in mm/s.

### linear acceleration: mm/s/s¶

Linear acceleration describes how fast the speed changes. This is expressed as the change of the millimeters per second, during one second (deg/s/s). This is also commonly written as \(mm/s^2\).

For example, you can adjust the acceleration setting of a
`DriveBase`

to change how
smoothly or how quickly it reaches the constant speed set point.

## Approximate and relative units¶

### percentage: %¶

Some signals do not have specific units. They range from a minimum (0%) to a maximum (100%). Specifics type of percentages are relative distances or brightness.

Another example is the sound volume, which ranges from 0% (silent) to 100% (loudest).

### relative distance: %¶

Some distance measurements do not provide an accurate value with a specific unit, but they range from very close (0%) to very far (100%). These are referred to as relative distances.

For example, the distance value of the `InfraredSensor`

is a relative distance.

### brightness: %¶

The perceived brightness of a light is expressed as a percentage. It is 0% when the light is off and 100% when the light is fully on. When you choose 50%, this means that the light is perceived as approximately half as bright to the human eye.

## Force¶

### force: N¶

Force values are expressed in newtons (N).

While we recommend working with newtons in your programs, you can use the following table to convert to and from other units.

mN | N | lbf | |

1 mN = | 1 | 0.001 | \(2.248 \cdot 10^{-4}\) |

1 N = | 1000 | 1 | 0.2248 |

1 lbf = | 4448 | 4.448 | 1 |

## Electricity¶

### voltage: mV¶

Voltages are expressed in millivolt (mV).

For example, you can check the voltage of the battery.

### current: mA¶

Electrical currents are expressed in milliampere (mA).

For example, you can check the current supplied by the battery.

### energy: J¶

Stored energy or energy consumption can be expressed in Joules (J).

### power: mW¶

Power is the rate at which energy is stored or consumed. It is expressed in milliwatt (mW).

## Ambient environment¶

### frequency: Hz¶

Sound frequencies are expressed in Hertz (Hz).

For example, you can choose the frequency of a beep to change the pitch.

### temperature: °C¶

Temperature is measured in degrees Celcius (°C). To convert to degrees Fahrenheit (°F) or Kelvin (K), you can use the following conversion formulas:

\(°\!F = °\!C \cdot \frac{9}{5} + 32\).

\(K = °\!C + 273.15\).