Rotational Dynamics (MCQ) PDF

Rotational Dynamics (MCQ) 1. In a uniform circular motion, the direction 9. A body of mass 0.4 kg is revolved in a of linear velocity is along the horizontal circle of radius 5m. If it a) Tangent to the curve path performs 120 rev/min, the cent...

Rotational Dynamics (MCQ) 1. In a uniform circular motion, the direction 9. A body of mass 0.4 kg is revolved in a of linear velocity is along the horizontal circle of radius 5m. If it a) Tangent to the curve path performs 120 rev/min, the centripetal b) Radius vector towards the centre force acting on it is. c) Perpendicular to the plane of the a) 42 N b) 82 N c) 162 N d) 322 N circular motion 10. A body of mass 1 kg is tied to a string and d) Radius vector revolved in a horizontal circle of radius 2. For a particle performing UCM, the 100 cm. If the breaking tension of the physical quantities are constant string is 100 N, the maximum velocity a) Speed and angular velocity with which the body can be revolved is b) Kinetic energy and radius vector a) 100 m/s b) 10 m/s c) 1 m/s d) 0.1 m/s c) Angular velocity and Kinetic energy 11. A stone of mass m is tied to the end of a d) ‘a’ and ‘c’ string of length l. When whirled in a 3. In a uniform circular motion, the velocity, horizontal circle, the tension in the string position vector and angular velocity are 1 is F. To whirl it in a radius of 𝑙 with half 2 a) Parallel to each other the initial angular velocity, the new b) Mutually perpendicular to each other tension in the string should be c) They are co-planer 1 1 1 d) The angle between then 450 𝑎)𝐹 𝑏) 𝐹 𝑐) 𝐹 𝑑) 𝐹 2 4 8 4. Angle between radius vector and 12. A car is moving along a horizontal curve centripetal acceleration is of radius 20 cm. If the coefficient of a) 0c b) c c) 2c d) None of these friction between the road and wheels of 5. The ratio of the frequencies of rotation of the car is 0.25, then its maximum safe the hour hand of a clock and the Earth is speed is a) 1: 12 b) 1: 2 c) 2:1 d) 12:1 a) 3 m/s b) 5 m/s c) 7 m/s d) 9 m/s 6. The angular speed of the wheels of a 13. The maximum safe speed of a vehicle on a bicycle is 8π rad/s. Their period of rotation circular track is 15 km/h. When the track is becomes wet, the maximum safe speed is a) 0.25 s b) 0.4 s c) /4 s d) 4s 10 km/h. the ratio of coefficient of friction 7. A car goes round a circular track of radius of dry track to that of the wet track is 50m with a speed of 25 m/s. its angular a) 2:3 b) 3:2 c) 9:4 d) 1:1 speed is 14. Angle of banking is independent of a) 0.5 rad/s b) 2 rad/s a) Velocity of vehicle c) 5 rad/s d) 1250 rad/s b) Radius of curvature 8. Two cars, A and B, take the same time to c) Mass of vehicle go around two concentric tracks of radii d) Width of road R1 and R2, respectively. The ratio of the 15. A car is traveling on a circular banked speed of car A to that of car B is road. The centripetal acceleration of a car 𝑅1 𝑅2 is provided by 𝑎) 1 𝑏) 𝑐) 𝑑) 2 𝑅2 𝑅1 a) Normal reaction b) Weight of a car c) Horizontal component of normal reaction  Rotational Dynamics (MCQ) d) Vertical component of normal reaction 22. A bucket of water, tied to a rope is to be 16. At what angle should a road be banked so rotated without spilling in a vertical circle that the vehicle may a bend of radius 10 m of radius 5 m. The minimum speed of the traveling with a speed of 10 m/s (g = 10 bucket at the highest position should be m/s2) a) 0.7 m/s b) 2 m/s c) 4 m/s d) 7 m/s a) 800 b) 450 c) 600 d) 900 23. A motorcyclist rides in a vertical circle in 17. A car can take a turn on a flat circular a hollow sphere of radius 5m. the roadway relying on friction with a minimum speed required so that he does maximum speed v. The car now takes a not lose contact with the sphere at the turn on another flat circular roadway of highest point is twice the radius. If the coefficient of a) 4.6 m/s b) 7 m/s c) 7.5 m/s d) 8 m/s friction between the tyres and the road 24. A small body of mass m, tied to a string surface is the same as before, the and revolved in a vertical circle is just able maximum speed at which the car can now to reach to the top of the path and be driven is complete the circle. The tension in the v v string at the lowest point of the path is a) 2v b) √2v c) d) √2 2 a) mg b) 2mg c) 4 mg d) 6 mg 18. An empty truck can take certain level turn 25. A particle moves in a circular path of at a maximum safe speed of 12 m/s radius 0.2 m with an angular speed 2 rad/s. without skidding. When the truck is If it has a constant angular acceleration of carrying a load equal to its own weight, 4 rad/s2 for 0.5 s, its angular speed the maximum speed at which the truck can becomes safely take the turn is a) 0.4 rad/s b) 2 rad/s c) 4 rad/s d) 8 rad/s a) 3 m/s b) 6 m/s c) 12 m/s d) 24 m/s 26. A flywheel rotates about a fixed axis and 19. The maximum speed with which a car can slows down from 400 4rpm to 200 rpm in be driven safely along a curve road of one minute. How many revolutions does radius 17.32 m and banked at 300 with the the flywheel complete in the same time? horizontal is a) 200 rev b) 400 rev c) 300 rev d) 500 rev a) 5 m/s b) 10 m/s c) 15 m/s d) 20 m/s 27. An object of mass 2 kg is whirled round in 20. The tangent of the banking angle is a vertical circle of radius 1m with a a) Proportional to v constant speed of 4m/s. then the maximum b) Inversely proportional to v2 tension in the string is (g = 10 m/s2 ) c) Proportional to the radius of the turn a) 32 N b) 52 N c) 72 N d) 92 N d) Proportional to v2 28. Two particles, whose masses are in the 21. The period of a conical pendulum, T, is ratio 7:3, go around two concentric tracks given by whose radii are in the ratio 1:2 If their L cos θ L sin θ linear speeds are in the ratio 1:2, their a) 2π√ b)2π√ centripetal accelerations are in the ratio g g a) 7:6 b) 1:1 c) 1:2 d) 1:4 g L cos θ 29. A small bob of mass m is tied to a string c)2π√ d) 2π√ and revolved in a vertical circle of radius L cos θ g  Rotational Dynamics (MCQ) r. If its speed at the highest point is √3𝑟𝑔, the tension in the string at the lowest point is a) 5 mg b) 6 mg c) 7 mg d) 8 mg 30. What will be the maximum speed of a car when it safely driven along a curve road of radius 100 m? (  0.2) a) 14 m/s b) 12 m/s c) 13 m/s d) 11 m/s