Practice Test 5 - AP Physics 2

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

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1. Two blocks, P and Q, have equal mass and start at $20^\circ$C. Each absorbs $600$ J. $c_P=900$ J/(kg·K), $c_Q=450$ J/(kg·K). Which ends cooler?
2. A resistor has constant resistance $R$. Over a short time, the current through it decreases from $3I$ to $I$. Compared to before, the power dissipated by the resistor becomes
3. A blackbody source is heated so its spectrum's peak shifts left (to shorter wavelength) and the area under the curve increases. As temperature increases, which statement correctly describes the spectrum?
4. A nucleus has 10 protons and 12 neutrons. After $\beta^{-}$ decay, its daughter has:
5. A closed single-loop circuit has an ideal $3.0\,\text{V}$ battery and a $6.0\,\Omega$ resistor. Which statement best describes the current in the circuit?
6. A capacitor is initially charged and then discharging through a resistor $R$ after a switch closes at $t=0$. Which statement best describes the energy stored in the capacitor as time increases?
7. A single loop includes an ideal $24\,\text{V}$ battery and two series resistors $R_1=4.0\,\Omega$ and $R_2=8.0\,\Omega$. Conventional current $I$ is clockwise. Traverse clockwise: battery from $-$ to $+$ is $+24$; each resistor with $I$ is $-IR$. Which equation correctly represents the loop?
8. A gamma-ray photon scatters from a nearly free electron, and the scattered photon has a longer wavelength than the incident photon. This supports the inference that the photon
9. A microwave beam in air travels horizontally. A detector shows the electric field oscillates vertically while the magnetic field oscillates into and out of the page. Which statement best describes electromagnetic waves?
10. Gamma rays of wavelength $2.00\ \text{pm}$ scatter from electrons; at $60^\circ$ the wavelength becomes $2.49\ \text{pm}$. The wavelength increase occurs because the photon
11. A fixed source charge $+Q$ is at the origin. Point A is at $r=0.20\,\text{m}$ and point B is at $r=0.40\,\text{m}$. A tiny test charge is placed at each point. Compared to B, the electric field magnitude at A is
12. Two small spheres are $0.30\,\text{m}$ apart: sphere 1 has charge $+q$ and sphere 2 has charge $-q$. Without changing the charges, the separation is doubled to $0.60\,\text{m}$. Compared to the original force magnitude, the new electrostatic force magnitude is
13. In Compton scattering, an incident photon of wavelength $\lambda$ scatters from an electron and emerges with wavelength $\lambda'>\lambda$. Which conclusion about light is supported by observing $\lambda'>\lambda$?
14. A sphere with charge $+q$ exerts an electrostatic force of magnitude $F$ on a second sphere with charge $+q$ at distance $d$. If the second sphere's charge becomes $-q$ while $d$ stays the same, the force on the second sphere is
15. A $50\ \text{g}$ piece of wax at $55^\circ\text{C}$ is placed in contact with a $200\ \text{g}$ metal block at $15^\circ\text{C}$ inside an insulated box. Which statement best describes the thermal energy flow?
16. A laser of wavelength $650\ \text{nm}$ passes through a single slit of width $0.20\ \text{mm}$ onto a distant screen. The slit width is then reduced to $0.10\ \text{mm}$ with the same laser. Compared to before, the central bright region on the screen becomes
17. An electron is released from rest in a region of space where there is a uniform electric field. It moves through a potential difference of $+100 \text{ V}$. What is the change in the kinetic energy of the electron?
18. A sample contains $^{60}\mathrm{Co}$, which undergoes beta-minus decay to $^{60}\mathrm{Ni}$ and emits an electron. Which statement best describes what changes in the nucleus?
19. A heat engine operates in a cycle between a hot reservoir at $500\,\text{K}$ and a cold reservoir at $300\,\text{K}$, absorbing $Q_h$ each cycle (spontaneous when running). Which conclusion is consistent with the second law?
20. A sound wave in air has $v=340\ \text{m/s}$ and $f=680\ \text{Hz}$. Which statement best describes its wavelength?

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