What is change in internal energy if 30j of heat are released from a system that does 50j of work on its surroundings

-80 J

Explanation:

The first law of thermodynamics states that:

where

is the change in internal energy of the system

Q is the heat absorbed by the system

W is the work done by the system

In this problem, we have:

Q = -30 J is the heat released by the system (negative because the system releases it)

W = +50 J is the work done by the system on the surrounding (positive since it is done by the system)

Therefore, the change in internal energy is

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.