# thermodynamics act

Name: ______________________YR.&amp;SEC. __________________Date: ________________ SCORE: ______
THERMODYNAMICS
1. What is thermodynamics?
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2. Differentiate heat and work.
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3. Define the First Law of Thermodynamics.
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Problem Solving : Show all calculations.
1. A system releases 125 kJ of heat while 104 kJ of work is done on the system. Calculate the change in internal
energy (in kJ). (2pts)
2. Calculate w for a system that absorbs 260 kJ of heat and for which ∆U= 157 kJ. Is the work done on or by the
system? Does the system expand or contract? (4pts)
3. You add coal to an old steam engine on a train. The coal adds 150kJ of energy into the engine. The engine then
does 120kJ of work. What is the change in internal energy of the engine?
4. An engine does 40J of work while losing 20J of thermal energy to its surroundings. What is the change of internal
energy of the engine?
5. 125 kJ of energy is added to a system while 104 kJ of work is done by the system. Calculate the change in internal
energy (in kJ).