# Speed

The Speed of an object is the rate at which the object's position is changing with time, relative to a reference point determined by the object's Relative to property. In terms of vector mathematics, the Speed is the magnitude of the object's Velocity Vector.

## Property Details

### Location

The Speed property for an object can be found in the Motion section of the Overview tab, or near the top of the Motion tab. For Galaxy objects, the Speed property is located in the Properties section of the Galaxy tab, and refers specifically to the Black Hole's Speed. For Galaxy Nebula objects, the Speed property is located in the Motion section of the Nebula tab. In the Motion tab, the Speed property can be expanded to show the object's Velocity Vector.

The Speed is also displayed in an object's mini-info panel. This Speed is always displayed relative to the Simulation Origin.

### Units

Speed can be viewed or edited using the following properties:

• The Speed of Light (lightspeed) = 2.99792458×108 m/s
• Kilometers per Second (km/s) = 1000 m/s
• Meters per Second (m/s) is the SI unit for speed
• Kilometers per Hour (km/h) = 0.2778 m/s

## Simulation Effects

### Motion

An object will a constant speed, V, will move a distance D in a period of time T, where

However, in the presence of forces like gravity, the speed of an object is usually not constant, and its motion is more complex.

### Collisions

The speed of an object affects both its momentum and kinetic energy, which determine the outcome of a collision with another object.