Question

In a closed system where kinetic, potential, and thermal energy are changing, the kinetic
energy decreases by 54 J, and the thermal energy increases by 13 J. What is the
change in the potential energy?

Answer 1

system is closed
so if
Ke = kinetic
U = potential
T = thermal
then
Ke + U + T = constant

Ke1 + U1 + T1 = Ke2 + U2 + T2
Ke2 = Ke1 - 54
T2 = T1 + 13

Ke1 + U1 + T1 = Ke1-54 + U2 + T1+13
so
41 = U2-U1