Answer:
E = 8.5 * 10^6 V/m
Explanation:
In general we have the following relation between the Electric Field and the Elecric Potential:

Due to the vector nature of the electric filed, we can only know the mean Electric field E across the membrane, and take it out from the integral, that is:
E = (ΔV)/L
Where L is the thickness of the membrane and ΔV is the potential difference.
Therefore:
E = 8.53933*10^6 V/m
rounding to the first tenth:
E = 8.5 * 10^6 V/m
I am not sure what this is
Here as we know that there is no loss of energy
so we can say that maximum kinetic energy will become gravitational potential energy at its maximum height
So here we have

here we have
v = 20 m/s
m = 8000 kg
now from above equation we have



so maximum height is 20.4 m