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.

m= 5 kg g= 9.8 m/s²h= 2.1 m

Substitute the values into the formula.

Multiply the numbers together.

1 kilogram square meter per square second ( 1 kg*m²/s²) is equal to 1 Joule (J). So, our answ er of 102.9 kg*m²/s² is equal to 102.9 J

The book has 102.9 Joules of gravitational potential energy.

Remains same. Here according to law of conservation of momentum, the system have momentum conserved and remains constant.
Given by the popular equation,
m1v1=m2v3
m1=Mass of billiard ball 1
m2= Mass of the 2nd ball
v1,v2 are the velocity of the ball 1,2 respectively.