During the construction of a building, the lightning conductor was left hanging in the air by mistake will it be effective? Explain.

During a thunder storm the movement of water molecules within the clouds creates friction partially causing the bottom part of the clouds to become negatively charged. This implies that the bottom of the cloud and the ground act as a parallel plate cpacitor . If the electric field between the cloud and ground exeeds the dielectric breakdown of the air (3xx10^(6)Vm^(-1)) lightning will occur. (a) If the bottom part of the cloud is 1000 m above the ground determine the electric potential difference that exists between the cloud and ground. (b) In a typical lightning phenomenon around 25 C of electrons are transferred from cloud to ground . How much electrostatic potential energy is transferred to the ground?

Take a small stone. Hold it in your hand. We know that the force gravity due to the earth acts on each and every object. When we were holding the stone in our hand, the stone was experiencing this force, but it was balanced by a force that we were applying on it in the opposite direction. As a result, the stone remained at rest. Once we release the stone from our hands the only force that acts on it is the gravitational force of the earth and the stone falls down under its influence. Whenever an object moves under the influence of the force of gravity alone, it is said to be falling freely. Thus the released stone is in a free fall. In free fall, the initial velocity of the object is zero and goes on increasing due to acceleration due to gravity of the earth. During free fall, the frictional force due to air opposes the motion of the object and buoyant force also acts on the object. Thus, true free fall is possible only in vacuum. For a freely falling object, the velocity on reaching the earth and the time taken for it can be calculated by using Newton's equations of motion. For free fall the initial velocity u=0 and the acceleration a=g . Thus, we can write the equations as v="gt",s=1/2"gt"^(2),v^(2)=2gs For calculating the motion of an object thrown upwards, acceleration is negative, i.e. in a direction opposite to the velocity and is taken to be -g. The magnitude of g is the same but the velocity of the object decreases due to -ve acceleration. The moon and the artificial satellites are moving only under the influence of the gravitational field of the earth. Thus they are in free fall. What is the initial velocity and what is the effect of gravitational acceleration on the object in free fall?