The distance, measured from one edge of a black band to the same edge of the next band, is 5.0 cm. what additional information is needed to determine the average speed of the picket fence as t moves through the photo gate?

In order to find the average speed we will use the formula

now here we know that distance from one edge to other edge is given as

now in order to find the average speed as per the formula above we need to know the time taken from one edge to other edge

so using above equation

here time can be found just by using the photo gates

If the photo gate will measure the time interval from one position to other then it will help to find the average speed

i think the answer is a, hope this : )