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Q21. Correct statement about warm-base glaciers:
Warm-base glaciers have water at the bed, allowing them to slide over the bedrock, unlike cold-base glaciers which are frozen to the bed.
Q22. The angle of inclination of the remanent magnetization of a volcanic rock measured at a location is 45°. The magnetic latitude of the location of the volcanic rock at the time of its magnetization is _________ °N. [round off to 1 decimal place]
Tan(Inclination) = 2 * Tan(Latitude). Tan(45) = 1. 1 = 2 * Tan(Lat). Tan(Lat) = 0.5. Lat = arctan(0.5) approx 26.56 degrees.
Q23. Assuming the rate of rotation of the Earth is 7.27 * 10^-5 radians/s and the radius of Earth is 6371 km, the centrifugal acceleration at 60 degrees latitude for a spherically rotating Earth is ______ * 10^-3 m/s2. [round off to 1 decimal place]
Centrifugal acceleration a = w^2 * R * cos(latitude). w = 7.27e-5, R = 6.371e6 m, lat = 60. a = (7.27e-5)^2 * 6.371e6 * 0.5 = 5.285e-9 * 3.1855e6 = 0.01683 m/s^2 = 16.8 * 10^-3 m/s^2.
Q24. The difference in arrival times of P- and S-waves generated by an earthquake and recorded at a seismological station is one second. Assuming a homogeneous and isotropic Earth, a P-wave velocity (VP) of 3 km/s, the ratio of P- to S-wave velocities (VP/VS) of 2.0, the distance between the station and the hypocenter is __________km. [round off to 1 decimal place]
Given Vp/Vs = 2, Vs = Vp/2 = 1.5 km/s. Time difference T = D/Vs - D/Vp = 1. D(1/1.5 - 1/3) = 1. D(2/3 - 1/3) = 1. D(1/3) = 1. D = 3 km.
Q25. For a productive alluvial aquifer with hydraulic conductivity = 105 m/day and hydraulic gradient = 0.01, the flow rate is _________ m/day. [round off to 2 decimal places]
Darcy's law gives the specific discharge (Darcy velocity) q = K * i. Calculation: 105 * 0.01 = 1.05 m/day.
Q26. The average bulk density of a fully saturated sandstone reservoir with a fractional porosity of 0.23 is ______ g/cc. [round off to 2 decimal places] [Assume matrix density for sandstone = 2.63 g/cc and fluid density = 1.05 g/cc]
Bulk density = (1 - porosity) * matrix_density + (porosity * fluid_density). Calculation: (0.77 * 2.63) + (0.23 * 1.05) = 2.0251 + 0.2415 = 2.2666. Rounded to 2 decimal places: 2.27.
Q27. A mineral of uniform composition is cut into a wedge shape. The birefringence of the wedge section is 0.012. The retardation at 40 µm thickness of the wedge is _______ nm. [in integer]
Retardation = Thickness * Birefringence. Thickness = 40 micrometers = 40,000 nm. Retardation = 40,000 * 0.012 = 480 nm.
Q28. The cross section of a river channel is approximated by a trapezium. The river has an average channel width of 40 m and average depth of 3 m. If the average flow speed is 2 m/s, the discharge rate is _________ m3/s. [in integer]
Discharge Q = Area * Velocity. Approximating Area = Width * Depth = 40m * 3m = 120 m^2. Q = 120 * 2 = 240 m^3/s.
Q29. If the shrinkage factor of a crude oil is 0.7, its formation volume factor is _____. [round off to 1 decimal place]
The formation volume factor (Bo) is the inverse of the shrinkage factor (1/S) or related to the volume change from reservoir to surface. Bo = 1 / 0.7 approx 1.43.
Q30. The strike and dip of the axial plane of a reclined fold is 022° and 28° SE, respectively. The plunge direction (in whole circle bearing) of the axis of the reclined fold is ______ degrees. [in integer]
In a reclined fold, the fold axis plunges down the dip of the axial plane. If the axial plane dips SE with a strike of 022, the dip direction is 022 + 90 = 112 degrees. Therefore, the plunge direction is 112 degrees.