Answer:
20 J
Explanation:
Given:
Weight of the book is,
Height or displacement of the book is,
The work done on the book to raise it to a height of 2 m on a shelf is against gravity. The gravitational force acting on the book is equal to its weight. Now, in order to raise it, an equal amount of force must be applied in the opposite direction.
So, the force applied by me should be equal to weight of the body and in the upward direction. The displacement is also in the upward direction.
Now, work done by the applied force is equal to the product of force applied and displacement of book in the direction of the applied force.
Therefore, work done is given as:
Therefore, the work done to raise a book to a height 2 m from the floor is 20 J.
The resistance of a conductor is inversely proportional to the cross sectional area of the conductor.
<u>Explanation:</u>
The resistors are used to resist or block the flow of current in any circuit. As per Ohm's law, resistance is inversely proportional to the current flow or charge in the circuit. But the resistance of a conductor will depend on the length of the conductor and cross sectional area of the conductor along with specific resistance of the material with which the conductor is made.
Here, Rho is the specific resistance, L is the length of the conductor and A is the cross sectional area of the conductor.
As the resistance offered by the conductor will be directly proportional to the length of the conductor and inversely proportional to the cross sectional area of the conductor. So the resistance of a conductor is inversely proportional to the cross sectional area of the conductor.