6. Suppose an ice skater is soing at 0.8 revolutions (rev) per second with her arns extended. She has a moment of ineria of 2.34 kg • m² with her arms extended and of 0.363 kg • m² with her a close to her body (appropriate for a 60-kg skater). What is her angular velocity in revolutions per second after she pulls in her arms?
(A) 2.2 rev/s
(B) 3.2 rev/s
(C) 4.2 rev/s
(D) 5.2 rev/s
(E) 6.2 rev/s

2. The Moon orbits Earth each 27.3 days and it has an average distance of 3.84×108 m from the center of Earth. Calculate the period of an artificial satellite orbiting at an average altitude of 1500 km above Earth's surface. The radius of Earth is 6380 km. (A) 0.57 hr (B) 1.9 hr (C) 5.7 hr (D) 19 hr (E) 57 hr

3. What is the final speed of the roller coaster shown in the figure if it starts from rest at the top of the 20.0 m hill and work done by frictional forces is negligible? The gravitational acceleration on Earth's surface is 9.8 m s-2. (A)2.4 m/s (B) 4.9 m/s (C) 9.8 m/s (D) 19.8 m/s (E) 29.4 m/s

4. The escape velocity (minimum velocity to escape the Earth's gravitational potential) for a 100-kg object on Earth is about 11 km/s. What is the escape velocity of a 50-kg object on the surface of Earth? (A) 11 km/s (B) 22 km/s (C) 5.5 km/s (D) 44 km/s (E) 2.75 km/s

5. At what temperature would helium atoms have an rms speed enough to escape the Earth's gravitational potential? The proton mass is kg. (A) 200 K (B) 600 K (C) 2×103 K (D) 6×103 K (E) 2×104 K

7. A block of mass oscillates at the end of a horizontal spring on a frionless surface. Al maximum extension,an identical block drops onto the top of the first block and sticks to it. How does the new period Tnew compare to the original period,T0? (A) Tnew = 0.5 T0 (B) Tnew = T0 (C) Tnew = √2 T0 (D) Tnew = 2 T0 (E) Tnew = 3 T0

8. What is the ratio of the ectrostatic force between an electron and proton separated by m to to the gravitational force between them? Their separation is the average separation in a bydrogen atom. The electron has a mass of  kg and a charge of . The gravional constant is G=N and the Coulomb constant is k = 8.99x109 N . (A) (B) (C) 2.3×10⁹ (D) 2.3×10¹⁹ (E) 2.3×10³⁹

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