The switch in the circuit in Fig. has been closed for a long time. At $t=0$, the switch is opened. a) Find $v_o$ for $t \geq 0$. b) Find $i_o$ for $t \geq 0$.

The reaction $2 \mathrm{Mg}(s)+\mathrm{O}_2(g) \longrightarrow 2 \mathrm{MgO}(s)$ is highly spontaneous and has a negative value for $\Delta S^{\circ}$. The second law of thermodynamics states that in any spontaneous process there is always an increase in the entropy of the universe. Is there an inconsistency between the above reaction and the second law?

Water at 70 kPa and $100^\circ C$ is compressed isentropically in a closed system to 4 MPa. Determine the final temperature of the water and the work required, in kJ/kg, for this compression.

Indicate whether the following statements are true or false. Explain. A closed system exergy balance consists of three major contributions: exergy change, exergy transfer, and exergy destruction.

A block of copper at a temperature of $50^{\circ} \mathrm{C}$ is placed in contact with a block of aluminum at a temperature of $45^{\circ} \mathrm{C}$ in an insulated container. As a result of a transfer of 2500 J of energy from the copper to the aluminum, the final equilibrium temperature of the two blocks is $48^{\circ} \mathrm{C}.$ What is the change in the energy of the Universe?

The switch in the circuit shown in Fig. has been closed for a long time. The switch opens at $t=0$. Find $v_e(t)$ for $t \geq 0$.

The switch in the circuit in Fig. has been closed for a long time and is opened at $t=0$. Find $i(t)$ for $t>0$.

The following exercise involves the Fundamental Counting Principle.

A restaurant offers the items listed in the table. How many different meals consisting of a main course, a drink, and a dessert can be selected at this restaurant?

In your own words, state the Pythagorean Theorem .

In Fig. P2.71 gate $A B$ is $3 \mathrm{~m}$ wide into the paper and is connected by a rod and pulley to a concrete sphere $(\mathrm{SG}=$ 2.40). To keep the gate closed, what will be the sufficient diameter of the sphere ?

In your own words, state the Pythagorean Theorem.

Which of the following accounts would be closed at the end of the year using the perpetual inventory system?

• a. Cost of Goods Sold
• b. Merchandise Inventory
• c. Accounts Receivable
• d. Accounts Payable

Nitrogen at $900\ \mathrm{kPa}$ and $300^{\circ} \mathrm{C}$ is expanded adiabatically in a closed system to $100\ \mathrm{kPa}$. Find the minimum nitrogen temperature after the expansion.

The switch in the circuit shown in Fig. has been closed for a long time. The switch opens at $t=0$. Find a) $i_o(t)$ for $t \geq 0$. b) $v_e(t)$ for $t \geq 0$