It is by gaining! I just learned this in school. Hope this helps:)
Answer:

Explanation:
The interaction of the piece of copper and water means that the first one need to transfer heat in order to reach a thermal equilibrium with water. Then:

After a quick substitution, the expanded expression is:



The final temperature of the system is:

Answer:
12,750
Explanation:
P = mv
Momentum = Mass x Velocity
Plug it in and finish equation
The atomic number of an element is the number of protons the element has, so the element with the atomic number 55 has 55 protons.