3000 J of heat is added to a system and 2500 J of work is done by the system. What is the change in internal energy of the system (in Joule)?

Question

BlackTom AI · Accepted Answer

Using the first law of thermodynamics, ΔU = Q − W, where Q is heat added to the system (positive when added) and W is work done by the system (positive when the system does work on the surroundings).

1) Relevant knowledge points and concepts
- First law of thermodynamics (conservation of energy for a thermodynamic system).
- Sign conventions: Q > 0 when heat is added to the system; W > 0 when the system does work on the surroundings. With this convention ΔU = Q − W gives the change in internal energy.
- Units: energy in joules (J).

2) Step-by-step reasoning
- Identify given quantities: Q = +3000 J (heat added), W = +2500 J (work done by the system).
- Substitute into the first law formula: ΔU = Q − W.

3) Complete calculation with intermediate steps
- Write the formula: ΔU = Q − W
- Substitute numbers: ΔU = 3000 J − 2500 J
- Compute difference: ΔU = 500 J

4) Why the correct answer is correct
- The system receives 3000 J of energy as heat but expends 2500 J doing work; the net energy retained as internal energy is the difference, 3000 − 2500 = 500 J. This directly follows conservation of energy and the chosen sign convention.

5) Why other common answers would be incorrect
- −500 J would be incorrect because that would imply the system lost internal energy; here heat input exceeds work done, so internal energy increases.
- 0 J would be incorrect because Q and W are not equal.
- 5500 J or 3000 J would be incorrect because they ignore subtracting the work done.
- Using the alternate form ΔU = Q + W could give a wrong sign if W is interpreted as work done by the system; that alternate form is valid only when W is taken as work done on the system.

6) Conclusion
- The change in internal energy is ΔU = 500 J, which matches the provided correct answer (500).

3000 J of heat is added to a system and 2500 J of work is done by the system. What is the change in internal energy of the system (in Joule)?数值题

类似问题

6.6 kJ of heat was released by a system, whilst also having 2.9 kJ of work done by it. What is the change in the internal energy of this system after these processes?

2000 J of heat is added to a system and 2500 J of work is done on the system. What is the change in internal energy of the system (in Joule)?

What quantities appear in the first law of thermodynamics?

1.50 moles of an ideal monatomic gas are initially at a temperature of 317 K. If the gas gains 2730 J of heat and performs 780 J of work, what is its final temperature?

The surroundings do 120 J of work on a gas. At the same time, the gas releases 23 J of heat. What is ΔE for this process? 02A

A perfectly insulated system has work done by it at a rate of 20 W. At what rate is the internal energy of the system changing?

A perfectly insulated system has work done by it at a rate of 13 W. At what rate is the internal energy of the system changing?

A system has a heat source supplying heat at a rate of 187 W and is doing work at a rate of 130 W. At what rate is the internal energy of the system changing?

更多留学生实用工具

智能学习助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单