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$54. At what depth below the earth surface the value of g reduces to one half of its value on the earths surfacea) R_{e} / 2 b) R_{e} / 4 c) R_{e} d) 2 R_{e}$  $62. The weight of a man in an elevator moving down with an acceleration of 9.8 \mathrm{~m} / \mathrm{s}^{2} will becomea) Doubleb) Halfc) Zerod) Unchanged$  $A body of moment of inertia I=0.80 \mathrm{~kg} \mathrm{} \mathrm{m}^{2} about a fixed axis rotates with a constant angular velocity of 100 rad s^{-1} . Calculate its angular momentum L and the torque to sustain this motion.$  $9. When a body moves in a circle the angle between its linear velocity and angular velocity is always.a) 180^{\circ} b) 0^{\circ} c) 90^{\circ} d) 45^{\circ}$  $Explain how many minimum number of geo-stationary satellites are required for global coverage of T . V transmission?$  $45. The value of gravitational constant was determined bya) Newtonb) Keplerc) Cavendishd) Maxwell$  $A student holds two dumb-bells without stretched arms while sitting on a turn table. He is given a push until he is rotating at certain angular velocity. The student then pulls the dumbbell towards his chest (Fig. 5.25). What will be the effect on rate of rotation?$  