We can solve the problem by using the first law of thermodynamics:
where
is the variation of internal energy of the system
Q is the heat added to the system
W is the work done by the system
In this problem, the variation of internal energy of the system is
While the heat added to the system is
therefore, the work done by the system is
Answer:
Explanation:
The center of mass of the system (two girls) is constant, as the velocity of the center of mass of the system is also constant.
<u>The initial velocity of the system is zero, since both girls are at rest.</u> So the velocity of the total system at any point should be zero as well.
This is true, because there is no friction between the girls and the ground. Otherwise, the velocity of the center of mass wouldn't be constant.