Answer:
To calculate the mechanical energy of the book just before it hits the ground, we need to consider its potential energy and kinetic energy.
The potential energy (PE) of the book at a height of 0.9 m can be calculated using the formula: PE = mgh, where m is the mass of the book, g is the acceleration due to gravity, and h is the height.
Step-by-step explanation:
Given:
Mass of the book (m) = 1.2 kg
Height (h) = 0.9 m
Acceleration due to gravity (g) = 9.8 m/s^2 (approximate value on Earth)
Now we can calculate the potential energy:
PE = mgh
= 1.2 kg * 9.8 m/s^2 * 0.9 m
≈ 10.584 J
The mechanical energy just before the book hits the ground is equal to its potential energy, which is approximately 10.584 J.
Among the given options, the closest value to 10.584 J is option C: 10.6 J.