Question

If 150 J of heat is added to a system and the work done by the system is 110 J, then the change in internal energy will be

• A. 40 J
• B. 110 J
• C. 150 J
• D. 260 J

Hint:

The first law of thermodynamics relates the change in internal energy to the heat added and the work done by the system. Remember that work done by the system is subtracted from the heat added to find the change in internal energy.

Answer 1

The Correct Option is A

According to the first law of thermodynamics: \[ \Delta U = Q - W \] where:
- \( \Delta U \) is the change in internal energy,
- \( Q \) is the heat added to the system,
- \( W \) is the work done by the system. Given:
- \( Q = 150 \, \text{J} \),
- \( W = 110 \, \text{J} \). Substituting the values into the formula: \[ \Delta U = 150 \, \text{J} - 110 \, \text{J} = 40 \, \text{J} \]
Thus, the change in internal energy is \( 40 \, \text{J} \). Therefore, the correct answer is: \[ \text{(A) } 40 \, \text{J} \]