XA 2 2.1.4 Quiz: First Law of Thermodynamics
Question 2 of 10
2 Points
Which of the following situations would cause the greatest increase in the
motion of molecules in a system?
A. Q = +50 J, W = -50 J
O B. Q = +50 J, W = +50 J
O c. Q = -50 J, W = -50 J
O D. Q = -50 J, W = +50 J

A.

Q = +50 J, W = -50 J

Explanation:

According to first law of thermodynamics, which can be expressed as;

dU = Q - W

Where

dU = change in internal energy

Q = added heat

W = work done by the system

If W is positive, work is done on the system. And if Q is negative, the system loses heat to the surrounding.

In the question above, the situation that would cause the greatest increase in the motion of molecules in a system will be option A

Q = +50 J, W = -50 J

Since the system gained heat and work is been done by the system.