Practice Test 9 - AP Physics 2

20 questions. Answer them in any order, then submit to see your score and every explanation.

Start practice test

1. A sealed piston-cylinder contains a gas (the system). Use $\Delta U=Q-W$ with $Q>0$ into the gas and $W>0$ done by the gas. In one process, $\Delta U=-120\ \text{J}$ while $Q=+50\ \text{J}$. Which statement correctly describes the work $W$?
2. A $+1.5\,\mu\text{C}$ charge moves from X at $V_X=-40\,\text{V}$ to Y at $V_Y=+10\,\text{V}$ due to an external agent. As the charge moves from X to Y, the electric potential energy will:
3. A thin diverging lens has focal length $f=-30\ \text{cm}$. An object is placed 90 cm in front of the lens. Which statement best describes the image?
4. A soap film (index greater than air) has air on both sides. Light reflects from the top and bottom surfaces and recombines in air. For normal incidence with wavelength $600\,\text{nm}$ in air, which thickness minimizes reflected light?
5. A student compares two ripple-tank setups with identical barriers and slit widths. Setup 1 uses waves with longer wavelength than setup 2. Both have the same amplitude. Which setup shows greater diffraction after the slit?
6. A $12\,\text{V}$ ideal battery powers a circuit where junction J splits into two branches that rejoin at K. Branch 1 contains a single resistor $R_1=3\,\Omega$. Branch 2 contains two series resistors $R_2=3\,\Omega$ and $R_3=3\,\Omega$. Which statement correctly compares the current in Branch 1 to the current in Branch 2?
7. Two identical bulbs are connected in series to an ideal battery and glow for $20\ \text{s}$. The same current flows through each bulb, and each bulb has the same resistance $R$. Compared to one bulb alone connected to the same battery, the power in each series bulb is
8. A $4\ \Omega$ resistor has a measured potential difference of $8\ \text{V}$ across it for several seconds. Which statement about its power is correct?
9. A wall section is replaced with either material M or N of equal thickness and area. Same indoor–outdoor $\Delta T$. $k_M>k_N$ but $c_M=c_N$. Which reduces heat loss rate?
10. In a wire, $1.0\ \text{C}$ of negative charge passes a point every $0.20\ \text{s}$, with electrons moving left steadily. Which statement best describes the current?
11. A sealed, rigid container holds liquid water at $60^\circ\text{C}$. A metal spoon at $10^\circ\text{C}$ is submerged and the container is insulated from the room. After a long time, the spoon and water reach equilibrium. Which statement best describes the thermal energy flow during the process?
12. A fixed amount of gas in a piston-cylinder is the system. Use $\Delta U=Q-W$ ($Q>0$ into gas, $W>0$ by gas). During a process, the gas releases $75\ \text{J}$ of heat ($Q=-75\ \text{J}$) and does $25\ \text{J}$ of work ($W=+25\ \text{J}$). Which statement correctly describes $\Delta U$?
13. An unstable $^{18}_{9}\text{F}$ nucleus becomes $^{18}_{8}\text{O}$ with unchanged mass number. Which particle is emitted?
14. A speaker emits a steady tone toward two hallways separated by a wall with an opening. Opening X is $0.20\,\text{m}$ wide and opening Y is $1.0\,\text{m}$ wide. The sound wavelength is about $0.34\,\text{m}$. Which opening produces greater spreading into the hallway?
15. A warm cup of coffee at $60^\circ\text{C}$ is left on a table in a $20^\circ\text{C}$ room. Over time it cools to room temperature; this cooling is spontaneous. Which statement best explains why the cooling occurs?
16. A narrow beam reflects from a flat mirror. The incident direction makes a $50^\circ$ angle with the surface, and the reflected direction leaves on the other side of the normal. What is the reflected angle with the surface?
17. A fixed amount of ideal gas is taken from state 1 to state 2 in a cylinder. The temperature is held constant at $300\,\text{K}$ while the volume increases from $1.5\,\text{L}$ to $3.0\,\text{L}$. If $P_1=300\,\text{kPa}$, then $P_2$ is
18. A $2.0\,\text{kg}$ ice block at $0^\circ\text{C}$ melts to liquid water at $0^\circ\text{C}$ while absorbing heat from a $0^\circ\text{C}$ reservoir; the melting is spontaneous at this phase boundary. Which conclusion about entropy is consistent with the second law?
19. Two small spheres are $0.30\ \text{m}$ apart. Sphere A has charge $+q$ and sphere B has charge $-2q$. If the distance is doubled, compared to the original force, the magnitude of the electric force between them is
20. A blackbody spectrum is measured at 1000 K and again at 2000 K. The higher-temperature curve has a shorter-wavelength peak and larger intensity. As temperature increases, what happens to the peak photon energy $E_{\text{peak}}$?

Practice tests