What property of an object can you determine using mass and volume

Can someone explain to me how to do this problem ?

Which of these questions might a character ask if the conflict is man versus self? a. which path should i take to better myself? b. which boulder will be too heavy for me to carry? c. which friend is going to ditch me today? d. all of the above

In a heat engine if 1000 j of heat enters the system and the piston does 500j of work, what is the final internal energy of the system if the inital energy was 2000 j1.write the equation2.list out your known variables 3. plug the numbers into the equations4.solve 5.write your solution statement that includes initial energy and final energy added.