Answer:
a)
, b) 
Explanation:
a) According to the First Law of Thermodinamics, the system is not reporting any work, mass or heat interactions. Besides, let consider that such box is rigid and, therefore, heat contained inside is the consequence of internal energy.

The internal energy for a monoatomic ideal gas is:

Let assume that cubical box contains just one kilomole of monoatomic gas. Then, the temperature is determined from the Equation of State for Ideal Gases:



The thermal energy contained by the gas is:


b) The physical model for the cat is constructed from Work-Energy Theorem:

The speed of the cat is obtained by isolating the respective variable and the replacement of every known variable by numerical values:



Nuclear fusion is where two Nucluir collide and form a new atom and release a tremendous amount of energy it requires a high activation energy and we cant use it for an energy source as its to dangerous
hope that helps

Explanation:
Natural length of a spring is
. The spring is streched by
. The resultant energy of the spring is
.
The potential energy of an ideal spring with spring constant
and elongation
is given by
.
So, in the current problem, the natural length of the spring is not required to find the spring constant
.

∴ The spring constant of the spring = 
Answer:
C
Explanation:
Energy is neither created or destroyed, but it can change forms...
Answer:

Explanation:
Given:
- mass of the body stretching the spring,

- extension in spring,

- velocity of oscillation,

- initial displacement position of equilibrium,

<u>According to given:</u>



<u>we know frequency:</u>



Now, for position of mass in oscillation:


at 
∴
∵ at 
