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Balikashram road, Opposite New Arts college boys hostel, Ahmednagar, Cell : 9850600386/9511626194, UNIT TEST, XII-2020-21, , PHYSICS, , ROTATIONAL DYANAMICS, , Time : 90 min, Marks-35, , *All questions are compulsory*, , SECTION ‘A’, Q.1. Select & write correct answer of the following questions., (i), , The diffrence in tension in the string at lowerst and highest point in the path of particle of mass ‘m’ performing, vertical circular motion., a) 2 mg, , (ii), , (iv), , c) 6 mg, , d) 8 mg, , b) 8 m, , c) 6 m, , d) 4 m, , Let I1 and I2 be the moment of inertia of two bodies of identical shape, the first made up of aluminion and, second of iron then, a) I1 < I2, , b) I1 = I2, , c) I1 > I2, , d) Relation between I1 and I2 depends on the actual shapes of bodies., , Angular momentum of two bodes of moment of inertia I1 and I2 (I1 > I2) is same. If E1 and E2 are, rotational KE then, a) E1 = E2, , (v), , b) 4 mg, , Wheel of mass 10 kg hads moment of inertia of 160 kgm2 about its own axis. The radius of guration., a) 10 m, , (iii), , [05], , b) E1 > E2, , c) E1 < E2, , d) E1 > E2, , The radius of guration of a solid sphere of mass M and radius R rotating about an axis with its diameter., , a), , 1, R, 5, , b), , 2, R, 5, , c), , 3, R, 5, , d), , 7, R, 5, , Q.2 Answer the following questions., , [05], , (i), , A car of mass 1500 kg round a curve of radius 250 m at 90 km/hr. Calculate the centripetal force acting, on it., , (ii), , If the radius of sphere is doubled by keeping the mass constant, compare the moment of inertia about any, diameter., , (iii), , State the expression for moment of inertia of a solid cylinder of uniform cross-section about its own axis, of symmetry., , (iv), , About which axis would a uniform cube have its minimum moment of inertia., 1

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SECTION ‘B’, Attempt any ‘FIVE’ questions., , [10], , Q.3. A racing car competes 5 rounds of a circular track in 2 minutes. Find the radius of the track if the car has, uniform centripetal aceleration of p2 m/s2., Q.4. Distinguish between centripetal force and centrifugal force., Q.5 State the following terms :, (i) Simple pendulum, , (ii) Conial pendulum, , Q.6. A flat curve on a highway has a radius of curvature 200 m. A car goes around a curve at a speech of, 32 m/s. What is the minimum value of coefficient of friction that will prevent the car from sliding?, (g = 9.8 m/s2), Q.7. Draw a diagram to represent conical pendulum in a non-inertial frame of reference and state the equation, of centrifugal force on the bob., Q.8. What is meant by mass tied to a rod? How is it differnent from mass tied to a string?, Q.9. State right hand thumb rule and find the direction of angular dispertion, , SECTION ‘C’, Attempt any ‘THREE’ questions., , [09], , Q.9. Explain the expression for upper limit on the speed when vehicle is at the top of a convex overbridge., Q.10. Derive an expression for kinetic energy of a rotating body ., Q.11. A solid cylinder of mass 20 kg rotates about its axis with angular speed 100 rad s–1. The radius the, cylinder is 0.25 m. What is the kinetic energy associated with the rotation of the cylinder? Why is the, mangitude of angular momentum of the cylinder about its axis?, Q.12. State and prove theorem of perpendicular axes., , SECTION ‘D’, Attempt any ‘TWO’ questions., , [06], , Q.12. State and prove theorem of parallel axes about moment of inertia., Q.13. i) What will be the duration of the day, if the earth sunddely shrinks to 1/27 of its orignal volume, mass, remaining unchanged?, ii) Prove the principle of conservation of angular momentum., , 2