Answer:
minimum two photogate
Explanation:
The photogate allows us to activate the measurement of time, so we must place at least two of them, one at the beginning of the movement to measure the initial time and another at the end of the movement to measure the final time, of course we must have measured the distance. This gives us the average speed between the two photocells
For measurements with more changes curves, slopes, one photogate must be placed at the beginning of the curve or slope and another at the end.
