Question

A system receives 225 J of heat to the surroundings while receiving 645 J of work. Calculate the change in the internal energy, δE, of the system in J.

a) 420 J
b) 570 J
c) 870 J
d) 1020 J

Answer 1

The change in the internal energy of the system is 870 J, computed using the first law of thermodynamics with the given heat transfer and work done on the system.

Step-by-step explanation:

To calculate the change in the internal energy (δE) of the system, we use the first law of thermodynamics. This law states that the change in internal energy is equal to the heat added to the system minus the work done by the system. The formula is δE = Q - W, where Q represents the heat transfer and W represents the work done.

In this case, the system receives 225 J of heat from the surroundings (positive Q) and has 645 J of work done on it (negative W since work is done by the system). Thus, we calculate the change in internal energy of the system as follows:

δE = Q - W
δE = 225 J - (-645 J)
δE = 225 J + 645 J
δE = 870 J

Therefore, the change in the internal energy of the system is 870 J.