# Speed measurement with IR sensor GP2Y0A02YKOF (Python)

This tutorial guides you through calculating a relative velocity by using the distance measurement of the GP2Y0A02YKOF infrared sensor over the time.

In order to be able to measure a speed at all, we must first be able to measure a distance to an object. Ultimately, the infrared distance sensor can do no more. Therefore, first read Speed measurement with IR sensor GP2Y0A02YKOF (Python).

## Calculating the speed

Let's take another closer look at the triangle from the previous chapter: So we need

`Speed = Distance / Time`

However, we do not want to go to the speed of sound now and check whether there is a deviation here.

I will show you how to measure the speed of movement of an object using this sensor. For that purpose we need to take two distance measurements in a short time apart and we have:

`distance2 - distance1 = distance speed at a given time`

If we make the measurements in a time period of 1 second, then we get the speed of movement of the object in cm/s.

When the object is moving in the opposite direction, the speed represented on the display has a negative sign.

## Programming the speed measurement

We change our code from the previous example as follows:

```import spidev
import time

spi = spidev.SpiDev()
spi.open(0,0)
spi.max_speed_hz=1000000

val = spi.xfer2([1,(8+channel)<<4,0])
data = ((val&3) << 8) + val

return data

if __name__ == "__main__":
dist1 = (16.2537 * v1**4 - 129.893 * v1**3 + 382.268 * v1**2 - 512.611 * v1 + 301.439) * 0.01

time.sleep(1)