How to find time using acceleration and displacement/distance

we can find time using equations of motion

Explanation:

We know that distance traveled by a moving object with given initial velocity, travel time and acceleration is given by the formula  

where u = initial velocity,

a = acceleration due to gravity,  

t = travel time and  

s = distance

Now if the object starts from rest,

we can write initial velocity = 0  

i.e u = 0  

and substitute it in the given formula which makes  

u*t = 0 and gives us

which can be written in terms of time as

or

So, if initial velocity is said to be zero or the object starts from rest point then we can find the time using acceleration and distance/displacement

the answer is neither ball has a charge.

because if they were both positively charged, they will repel each other.

if they were positively and negatively charged, they will seek.