13. As a solid disk rolls over the top of a hill on a track, its speed is 80 cm/s. If friction is negligible, how fast is the disk moving when it is 18 cm below the top?
(A) 5.2 m/s
(B) 3.5 m/s
(C) 2.4 m/s
(D) 1.7 m/s
(E) 0.2 m/s

9. For a uniform-density, spherical object with a mass M and a radius R. what is its gravional potential energy?(A) -5GM²/3R (B) -GM²/5R (C) -3GM²/4R (D) -2GM²/3R (E) -3GM²/5R

10. Calculate the kinetic energy of a photon with a wavelength of 500 nm and the kinetic energy of an electron that has the same momentum as the photon . What is the ratio of ? The Planck cont is is h =. (A) 4.1×10⁻⁵ (B) 4.1×10⁻² (C) 4.1×10² (D) 4.1×10³ (E) 4.1×10⁵

11. How does the spectrum of a molecule differ from the spectrum of an atom? (A) A molecule does not have spectral lines due to electrons changing energy levels. (B) A molecule has additional spectral lines due to changes in its rotational and vibrational energies. (C) Molecules only have spectral lines at ultraviolet wavelengths. (D) Most atoms only have spectral lines at infrared wavelengths. (E) An atom has a wider range of spectral lines than molecules.

12. What is the kinetic energy of an electron moving with a speed of v = 0.85c? (A) 0.511 MeV (B) 0.370 MeV (C) 0.464 MeV (D) 0.185 MeV (E) 0.821 MeV

14. A point explosion with thermal energy E occurs at time t = 0, driving a spherical shock wave into a uniform medium of density p. From dimensional analysis, the radius of the shock R should have a time dependence of (A)(B)(C)(D) R ∝ t (E)

15. Consider a surface water wave with a wavelength λ (and thus a wavenumber k = 2π/λ) propagating in the ocean with a depth H. The gravitational acceleration is g. In the case of λ<<H, the wave velocity is (A) (B)(C)(D)(E)

16. A copper can of negligible heat capacity contains 1.0 kg of water just above the freezing point. A similar can contains 1.0 kg of water just below the boiling point. The two cans are brought into thermal contact. What is the change in entropy of the system? The specific heat capacity of water is 4180 J . (A) +404 J/K (B) +202 J/K (C) +101 J/K (D) The entropy is unchanged (E) -202 J/K

17. What is the work done by the magnetic force on a straight wire 10 cm long carrying a current of 12 A that moves by 2 m in a magnetic field of 2 T perpendicular to the wire? (A) 2.4 J (B) 1.2 J (C) 7.2 J (D) 4.8 J (E) 0

18. Find the center of mass of a right circular cone (as shown in the figure) of height h, radius r, and constant density. (A) h/4 (B) h/3 (C) 2h/3 (D) h/5 (E) 2h/5

1. Which of the following is TRUE regarding Rhizobium-legume symbiosis?(A) The plant supplies nitrogen to the bacteria(B) The bacteria convert ammonia to nitrate for plant use(C) The plant provides carbohydrates and low-oxygen conditions(D) The bacteria live freely in the xylem vessels