A potato cannon has the fuel combusted, generating a lot of heat and pressure, which launch a potato. The combustion process _____ the internal energy, while launching the potato _____ the internal energy of the potato cannon. (a) increases, increases
(b) increases, decreases
(c) decreases, increases
(d) decreases, decreases

Video Transcript

This is College Physics Answers with Shaun Dychko. In a potato cannon, some fuel is combusted like maybe some hair spray is burned with piezoelectric lighter from a barbecue which I have done and it's fun and it generates a lot of heat and pressure, and it launches a potato and the combustion process increases the internal energy because it adds heat. As you know you've Delta U equals heat added to the system minus work done by the system and so the combustion is a positive Q so it increases internal energy or as launching the potato means the potato cannon is doing work on the potato and so that makes a positive W which reduces internal energy and so the answer is B.