17.Consider a parallel-plate capacitor of plate area A and plate separation. A potential difference Vo is applied between the plates. The battery is then disconnected, and a dielectric slab of thickness b and dielectric constant k is placed between the plates. Assuming A 100cm² , d 1.00cm, Vo 90V, b 0.8cm, k 2.00. What is the capacitance with the slab in place? ( )
(A)14.8pF
(B)16.8pF
(C)17.9pF
(D)20.9pF
(E)21.9pF 

13.A thin rod whose length L is 10cm and whose mass m is 100g, suspended at its midpoint from a long wire. Its period Ta of angular SHM (Simple Harmonic Motion) is measured to be 2.50 s. An irregularly shaped object is then hung from the same wire and its period Tb is found to be 5.0s. What is the rotational inertia of the irregular object about its suspension axis? (The rotational inertia for a rod is  mL2  ) (A) (B) (C) (D) (E)

14.In high-speed motion through air, the resisting force is approximately  F = cv2 . For a human body falling through air in a spread-eagle position, c is about 0.25kg/m. An 80kg sky diver jumps out of an airplane and reaches terminal speed before opening the parachute. What is the terminal speed? (A)49m/s (B)56m/s (C)72m/s (D)84m/s (E)98m/s

15.A neutral water molecule (H2O) in its vapor state has an electric dipole moment of magnitude  6.2 ́ 10Cm. How far apart are the molecule’s center of positive and negative charge? (A)1.9pm (B)2.9pm (C)3.9pm (D)4.9pm (E)5.9pm .

16.In a mass spectrometer, the initally stationary ion is accelerated by the electric field due to a potential V. The ion enters a separator chamber in which a uniform magnetic field B is perpendicular to the path of the ion. The magnetic field causes the ion to move in a semicircle, striking a photographic plate at distance x from the entry slit. Suppose that B 80mT and V 1000 Volts, and ion of charge q +1.60 ́ C strikes the plate at x 1.63m, what is the mass of the ion? (A)185.7u (B)204.9u (C)224.6u (D)241.5u (E)267.8u

18.A 200g top spinning at 20 rev/s makes an angle of 30° to the vertical and precesses at a rate of 1 rev per 10.0s. If its CM (Center of Mass) is 4.0cm from its tip along its symmetry axis, what is the moment of inertia of the top? (A) (B) (C) (D) (E)

19.A phone cord is 4.00m long. The cord has a mass of 0.200kg. If a transverse wave pulse travels from the receiver to the phone box in 0.100s, what is the tension in the cord? (A)50.0N (B)60.0N (C)70.0N (D)80.0N (E)90.0N

20.A thermodynamic system undergoes a process in which its internal energy decreases by 500J. If at the same time, 220J of work is done on the system, what is the thermal energy transferred to or from it? (A)280J (B)280J (C)720J (D)720J (E)1220J

21.A dipole for which p m is in a uniform field E 7 104 N /C  . What is the external work needed to rotate the dipole from alignment with the field to angle 60° to the field? ( cos60 o 0.5;sin 60o 0.9   ) (A)(B)  (C)   (D) (E)

22.A 5A current flows in a circular loop of radius 2cm. The axis of the loop is at 30° to a uniform field 0.06T. What is the magnitude of the torque on the loop? (A) (B) (C) (D) (E)

23.A 15pF parallel-plate capacitor is connected to a 50V battery. The area of each plate is 80cm2 . What is the energy density in the fiele? ( ) (A)  (B) (C)  (D) (E)