The 5 kg red book is about to fall from a 2.1 m high bookshelf. What is its PE?

Use g = 9.8 m/s2 for the acceleration due to gravity.

Explanation:

Potential energy is the energy an object possesses due to position. The formula is:

where m is the mass, g is the acceleration due to gravity, and h is the height.

We know the book is 5 kilograms and is on a 2.1 meter high bookshelf. Since this is on Earth, the acceleration due to gravity is 9.8 meters per square second.

Substitute the values into the formula.

Multiply the numbers together.

The book has 102.9 Joules of gravitational potential energy.

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

at positions a, g kinetic energy is maximum.

at position d, potential energy is maximum.