Question

Calculate the value of E in joules for a system that loses 31 J of heat and has 150 J of work performed on it by the surroundings

Answer 1

To calculate the value of \( E \) (the internal energy of the system), we can use the first law of thermodynamics, which states:

\[
\Delta U = Q + W
\]

Where:
- \( \Delta U \) is the change in internal energy (which we can denote as \( E \)).
- \( Q \) is the heat added to the system (if the system loses heat, \( Q \) will be negative).
- \( W \) is the work done on the system (if work is done on the system, \( W \) is positive).

In this case:
- The system loses 31 J of heat, so \( Q = -31 \, \text{J} \).
- The system has 150 J of work performed on it by the surroundings, so \( W = 150 \, \text{J} \).

Now we can substitute these values into the equation:

\[
E = Q + W
\]
\[
E = (-31 \, \text{J}) + (150 \, \text{J})
\]
\[
E = -31 + 150
\]
\[
E = 119 \, \text{J}
\]

Thus, the value of \( E \) is \( 119 \, \text{J} \).