Question

an open system starts with 52 j of mechanical energy. the energy changes to 45 j of mechanical energy and 2 j of thermal energy. what is the final total energy of the system?
a. 9 j
b. 54 j
c. 47 j
d. 50 j

Explanation:

Step1: Identify energy components

The final - state has mechanical energy and thermal energy.

Step2: Calculate total energy

The total energy $E$ is the sum of mechanical energy $E_m$ and thermal energy $E_t$. Given $E_m = 45\ J$ and $E_t=2\ J$, so $E = E_m + E_t$.
$E=45 + 2$
$E = 47\ J$

Answer:

C. 47 J