**MCQ on Angular momentum :**

**MCQ on Angular momentum :**

**1. The dimensional formula for angular momentum is________**

(a) L² M¹ T-¹

(b) L¹ M¹ T-²

(c) L² M² T-²

d) L³ M⁰ T-²

**Answer: A**

**2. The SI unit of angular momentum is________**

(a) kg m/s

(b) kg m²/s

(c) kg² m/s²

(d) kg m²/s²

**Answer: B**

**3. What is moment of momentum?**

(a) Moment of a force

(b) Moment of inertia

(c) Torque

(d) Angular momentum

**Answer: D**

**4. A child is sitting near the edge of a rotating platform. If the child starts moving from the circumference towards the centre of the platform, then the angular velocity of the platform will_______**

(a) increase

(b) decrease

(c) become zero

(d) not change

**Answer: A**

**5. A dancer on ice starts spinning faster, when she folds her arms. This is due to________**

(a) decrease in friction at the skates

(b) increase in angular momentum

(c) decrease in angular momentum

(d) constant angular momentum and decrease in moment of inertia

**Answer: D**

**6. If a person, sitting on a rotating table, with his arms outstretched, suddenly lowers his hands, then____**

(a) his angular velocity decreases

(b) his angular velocity doesnot change

(c) his angular momentum increases

(d) his moment of inertia decreases

**Answer: D**

**7. A horizontal disc is rotating about a vertical axis passing through its centre. A piece of wax falls on it and sticks to it at a point which is very near to its edge. In this case the angular velocity of the disc______**

(a) will decrease

(b) will increase

(c) will become zero

(d) will remain unchanged

**Answer: A**

**8. Angular momentum is________**

(a) a scalar

(b) an axial vector

(c) a polar vector

(d) a null vector

**Answer: B**

**9. When the divers, jump from the diving board of a swimming pool they have to use the principle of conservation of_____**

(a) Mass

(b) Energy

(c) Angular momentum

(d) Linear momentum

**Answer: C**

**10. Angular momentum is_________**

(a) a scalar

(b) a vector directed along the radius

(c) a vector directed along the axis of rotation

(d) a veector perpendicular to the axis of rotation

**Answer: C**

**11. Angular momentum is the product of________**

(a) mass x acceleration

(b) mass x velocity

(c) moment of inertia and angular acceleration

(d) moment of inertia and angular velocity

**Answer: D**

**12. L² M¹ T-¹ is the dimensional formula for__________**

(a) Force

(b) Moment of Inertia

(c) Work

(d) Angular Momentum

**Answer: D**

**13. If the external torque acting on a body is zero, then its_________**

(a) angular momentum is zero

(b) angular momentum is conserved

(c) angular momentum is maximum

(d) angular acceleration is maximum

**Answer: B**

**14. When the external torque acting on a system is zero, then there will be conservation of_______**

(a) total energy

(b) angular momentum

(c) linear momentum

(d) mass

**Answer: B**

**15. When a torque acting on a system is increased, then which one of the following quantities will increase_________**

(a) linear momentum

(b) Angular momentum

(c) force

(d) Displacement

**Answer :B **

**16. The angular momentum of a system of particles is not conserved if_______**

(a) a net external force acts upon the system

(b) a net external torque acts upon the system

(c) a net external impulse acts upon the systemn

(d) a pseudo force acts upon the system

**Answer: B**

**17. A man standing on a rotating horizontal circular table, suddenly sits down. What is conserved in this process?**

(a) kinetic energy

(b) angular speed

(c) angular momentum

(d) linear momentum

**Answer: C**

**18. A particle performs a uniform circular motion with angular momentum L. If its angular frequency is halved and the rotational kinetic energy is doubled, then the new angular momentum will be_____**

(a) 2L

(b) 3L

(c) 4L

(d) L/4

**Answer: C**

**19. A body of mass 2 kg is rotating on a circular path of radius 0.5 m, with an angular velocity of 20 rad/s. If the radius
of the path is doubled, then the new angular velocity will be_______**

(a) 5 rad/sec.

(b) 2.5 rad/sec.

(c) 10 rad/sec.

(d) 8 rad/sec.

Answer: A

**20. When a mass is rotating in a plane about a fixed point, its angular momentum is directed along_______**

(a) its radius

(b) the tangent to the orbit

(c) the axis of rotation

(d) at an angle of 45 to the plane of rotation

Answer: C

**21. A circular disc rotates about an axis passing through its centre with a certain angular velocity. Suddenly a small piece of the disc is broken from the edge and falls down. Then_________**

(a) Its M.I will increase and angular velocity will decrease

(b) Its M.I will decrease and the angular velocity will increase

(c) Both the M.I. and the angular velocity will increase

(d) Both the M.I and the angular velocity will deerease

Answer: B

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