Sign convention for work and heat

Question 1

Work done by a system on the surroundings is pos or neg?

Answer 1

Work done by a system on the surroundings is positive (+)

Question 2

Work done by a system on the surroundings is positive (+) give an example of this

Answer 2

• Expansion: The gas does work on the environment.

Question 3

Work done on a system by the surroundings is positive or negative?

Answer 3

Work done on a system by the surroundings is negative (-)

Question 4

Work done on a system by the surroundings is negative (-). give an example of this

Answer 4

Compression: The environment does work on the system.

Question 5

Heat transfer to a system is normally taken to be positive or negative with respect to the system?

Answer 5

Heat transfer to a system is normally taken to be positive with respect to the system. (+Q)

Question 6

how can energy be transferred in or out of a control system?

Answer 6

Energy may be transferred into or out of a control volume by heat.

Question 7

Heat transfer from a system to the surroundings is normally taken to be positive or negative?

Answer 7

Heat transfer from a system to the surroundings is normally taken to be
negative (-)

Question 8

what is the process in which there is no heat transfer between a system and its surroundings

Answer 8

an adiabatic process