3. A 3.0 g bullet traveling at a speed of 400 m/s enters a tree and exits the other side with a speed of 200 m/s. Where did the I bullet's lost KE go, and what was the energy transferred? Solution:

I had two questions: 1) Shouldnt the equation be : Change of internal energy= Change in Ke or KEi +Ui=KEf+Uf .. I cant seem to understand how the change in KE+ Change in Internal Energy equals 0 2) Also, it has a note which says that if the bullet alone was chosen as a system, then work would be done on it and the heat transfer woudl occur. How would one formulate an equation for this?

Explanation:

are there answer choices to this question? this seems like a question where you have options to choose from.