Position vs time calculate the slope of the line on the graph using the formula the slope of the line /s

That was pretty clever, how you neatly and cleanly cut off the part of the photo that shows the formula we're supposed to use.

At time=0, the position is zero, and at time=5 sec, the position is 20 m.

Slope = (change in position)/(change in time)

Slope = (20m - 0m) / (5s - 0s)

Slope = (20m) / (5s)

Slope = 4 m/s

force required to detach it is given by

charges are taken to be fundamental charge

now we have

so above is the minimum distance at which it will detach