here the charge density of metal plate is given as

now the electric field is given Gauss law

now here E = constant
so we will have

Since total area on both sides of plate will be double and becomes 2A



Now if we will find the electric field inside the metal plate
Then as we know that total charge inside the plate will always be zero
so we have

Answer:
14 m/s
Explanation:
We can solve the problem by using the law of conservation of energy.
At the beginning, when the ball is thrown from the ground, it has only kinetic energy, which is given by

where m = 5.9 kg is the mass of the ball and v is its initial speed.
As the ball goes up, its speed decreases, so its kinetic energy decreases and converts into gravitational potential energy. When the ball reaches its maximum height, the speed has become zero, and all the kinetic energy has been converted into gravitational potential energy, given by:

where g = 9.8 m/s^2 is the gravitational acceleration and h = 10 m is the maximum height reached by the ball.
Since we can ignore air resistance, energy must be conserved, so the initial kinetic energy must be equal to the final potential energy of the ball, so we can write:

And we can solve the equation to find v, the initial speed of the ball:

Answer:
1) The net electric field at any location inside a block of copper is zero if the copper block is in equilibrium.
2) In equilibrium, there is no net flow of mobile charged particles inside a conductor.
3) If the net electric field at a particular location inside a piece of metal is not zero, the metal is not in equilibrium.
Explanation:
1) and 3) A block of copper is a conductor. The charged particles on a conductor in equilibrium are at rest, so the intensity of the electric field at all interior points of the conductor is zero, otherwise, the charges would move resulting in an electric current.
2) The charged particles on a conductor in equilibrium are at rest.