Answer:
10000 V
0.00225988700565 m²

Explanation:
E = Electric field = 
d = Gap = 2.5 mm
Q = Charge = 80 nC
= Permittivity of free space = 
Potential difference is given by

The potential difference between the plates is 10000 V
Area is given by

The area of the plate is 0.00225988700565 m²
Capacitance is given by

The capacitance is 
v = initial velocity of launch of the stone = 12 m/s
θ = angle of the velocity from the horizontal = 30
Consider the motion of the stone along the vertical direction taking upward direction as positive and down direction as negative.
v₀ = initial velocity along vertical direction = v Sinθ = 12 Sin30 = 6 m/s
a = acceleration of the stone = - 9.8 m/s²
t = time of travel = 4.8 s
Y = vertical displacement of stone = vertical height of the cliff = ?
using the kinematics equation
Y = v₀ t + (0.5) a t²
inserting the values
Y = 6 (4.8) + (0.5) (- 9.8) (4.8)²
Y = - 84.1 m
hence the height of the cliff comes out to be 84.1 m
It's the energy your body spends to just keep you breathing and your heart beating ... just being alive, without trying to DO anything.
1. friction between water molecules
2. the wave spreads out onto a larger and larger area, so per unit area, the energy of the wave goes down