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:

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.

there are no contact forces mentioned on the list of choices that you've provided.