Question

A system absorbs 50 J of heat and does 10 J of work. What is the change in internal energy (\(\Delta U\)) of the system?

• A. \(\Delta U = 60 \, \text{J}\)
• B. \(\Delta U = 40 \, \text{J}\)
• C. \(\Delta U = 50 \, \text{J}\)
• D. \(\Delta U = -10 \, \text{J}\)

Hint:

Remember, the first law of thermodynamics states that the change in internal energy is equal to the heat added to the system minus the work done by the system.

Answer 1

The Correct Option is B

According to the first law of thermodynamics: \[ \Delta U = Q - W \] Where: - \(\Delta U\) is the change in internal energy,
- \(Q\) is the heat absorbed by the system,
- \(W\) is the work done by the system.
Given:
- \(Q = 50 \, \text{J}\) (heat absorbed),
- \(W = 10 \, \text{J}\) (work done by the system). Substitute the values into the equation: \[ \Delta U = 50 \, \text{J} - 10 \, \text{J} = 40 \, \text{J} \] Therefore, the change in internal energy is \(40 \, \text{J}\).