What will be the change in internal energy when work done by the system is 50 kJ and heat absorbed is 140 kJ?
Correct answer: D. 90 kJ
- A. -190 kJ
- B. 190 kJ
- C. -90 kJ
- D. 90 kJ
Explanation
According to the first law of thermodynamics, if a system absorbs 140 kJ of heat energy (Q) and uses 50 kJ to do work (W) on its surroundings, its internal energy would increase by 90 kJ.Mathematically,∆Q = ∆W + ∆U140 kJ = 50 kJ + ∆U∆U = (140 - 50) kJ∆U = 90 kJConventionally, heat absorbed, work done by the system on surroundings, and increase in internal energy are all taken as positive.
Last updated
About First Law of Thermodynamics
The first law relates heat supplied, work done and the change in internal energy through energy conservation. Problems use sign conventions and apply the law to isothermal, adiabatic, isobaric and isochoric processes. Internal energy is a state function, while heat and work depend on the path followed.
Practise Thermodynamics
714 free Thermodynamics MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
110 J of heat is added to a gaseous system, whose internal energy change is 40 J, then the amount of external work done is
1st law of thermodynamics is consequence of conservation of
A Carnot engine operates between reservoirs at 600 K and 300 K. Its maximum possible efficiency is
A carnot engine working between 200k and 400k has a work output of 600 J per cycle. How much heat energy is supplied to the engine from the source of each cycle.
A chemical system is sealed in a strong rigid container at room temp and then heated vigorously change in work done during the process is: