Home
Class 11
PHYSICS
To maintain a rotor at a uniform angular...

To maintain a rotor at a uniform angular speed of 200 rad s-1, an engine needs to transmit a torque of 180 N m. What is the power required by the engine ? (Note: uniform angular velocity in the absence of friction implies zero torque. In practice, applied torque is needed to counter frictional torque). Assume that the engine is 100% efficient.

Text Solution

Verified by Experts

`36kW`
Promotional Banner

Topper's Solved these Questions

  • SYSTEMS OF PARTICLES AND ROTATIONAL MOTION

    NCERT GUJARATI|Exercise EXERCISES (TRUE OR FALSE)|5 Videos

  • SYSTEMS OF PARTICLES AND ROTATIONAL MOTION

    NCERT GUJARATI|Exercise EXERCISES (TRUE OR FALSE)|5 Videos

  • PHYSICAL WORLD

    NCERT GUJARATI|Exercise EXERCISES|8 Videos

  • THERMAL PROPERTIME OF MATTER

    NCERT GUJARATI|Exercise EXERCISES|31 Videos

Similar Questions

Explore conceptually related problems

A 100 turn closely wound circular coil of radius 10 cm carries a current of 3.2 A. (a) What is the field at the centre of the coil? (b) What is the magnetic moment of this coil? The coil is placed in a vertical plane and is free to rotate about a horizontal axis which coincides with its diameter. A uniform magnetic field of 2T in the horizontal direction exists such that initially the axis of the coil is in the direction of the field. The coil rotates through an angle of 90^@ under the influence of the magnetic field. (c) What are the magnitudes of the torques on the coil in the initial and final position? (d) What is the angular speed acquired by the coil when it has rotated by 90^@ ? The moment of inertia of the coil is 0.1 kg m^2 .

On a circular turn, table rotating about its center horizontally with uniform angular velocity rad/s placed two blocks of mass 1kg and 2kg, on a diameter symmetrically about center. Their separation is 1m and friction is sufficient to avoid slipping. The spring between them as shown is stretched and applied force of SN. lf f_(1) and f_(2) are values of friction on 1 kg & 2kg block respectively:-

Separation of Motion of a system of particles into motion of the centre of mass and motion about the centre of mass : (a) Show p=p_(i).+m_(i)V where p_(i) is the momentum of the ith particle (of mass m_(i) ) and p_(i).=m_(i)v_(i). . Note v_(i). is the velocity of the i^(th) particle relative to the centre of mass Also, prove using the definition of the centre of mass Sigmap_(i).=0 (b) Show K=K.+(1)/(2)MV^(2) where K is the total kinetic energy of the system of particles, K. is the total kinetic energy of the system when the particle velocities are taken with respect to the centre of mass and (1)/(2)MV^(2) is the kinetic energy of the translation of the system as a whole (i.e. of the centre of mass motion of the system). The result has been used in Sec. 7.14). (c ) Show vecL=vecL.+vecRxxvec(MV) where vecL.=Sigmavec(r_(i)).xxvec(p_(i)). is the angular momentum of the system about the centre of mass with velocities taken relative to the centre of mass. Remember vec(r._(i))=vec(r_(i))-vecR , rest of the notation is the velcities taken relative to the centre of mass. Remember vec(r._(i))=vec(r_(i))-vecR rest of the notation is the standard notation used in the chapter. Note vecL , and vec(MR)xxvecV can be said to be angular momenta, respectively, about and of the centre of mass of the system of particles. (d) Show vec(dL.)/(dt)=sumvec(r_(i).)xxvec(dp.)/(dt) Further, show that vec(dL.)/(dt)=tau._(ext) where tau._(ext) is the sum of all external torques acting on the system about the centre of mass. (Hint : Use the definition of centre of mass and Newton.s Thrid Law. Assume the internal forces between any two particles act along the line joining the particles.)

NCERT GUJARATI-SYSTEMS OF PARTICLES AND ROTATIONAL MOTION-EXERCISES
  1. (a) A child stands at the centre of a turntable with his two arms outs...

    Text Solution

    |

  2. A rope of negligible mass is wound round a hollow cylinder of mass 3 k...

    Text Solution

    |

  3. To maintain a rotor at a uniform angular speed of 200 rad s-1, an engi...

    Text Solution

    |

  4. From a uniform disk of radius R, a circular hole of radius R/2 is cut ...

    Text Solution

    |

  5. A metre stick is balanced on a knife edge at its centre. When two coin...

    Text Solution

    |

  6. A solid sphere rolls down two different inclined planes of the same he...

    Text Solution

    |

  7. A hoop of radius 2 m weighs 100 kg. It rolls along a horizontal floor ...

    Text Solution

    |

  8. The oxygen molecule has a mass of 5.30 × 10^(-26) kg and a moment of i...

    Text Solution

    |

  9. A solid cylinder rolls up an inclined plane of angle of inclination 30...

    Text Solution

    |

  10. As shown in Fig.7.40, the two sides of a step ladder BA and CA are 1.6...

    Text Solution

    |

  11. A man stands on a rotating platform, with his arms stretched horizonta...

    Text Solution

    |

  12. A bullet of mass 10 g and speed 500 m/s is fired into a door and gets ...

    Text Solution

    |

  13. Two discs of moments of inertia I(1) and I(2) about their respective a...

    Text Solution

    |

  14. (a) Prove the theorem of perpendicular axes. (b) Prove the theorem o...

    Text Solution

    |

  15. Prove the result that the velocity v of translation of a rolling body ...

    Text Solution

    |

  16. A disc rotating about its axis with angular speed ω(o) is placed light...

    Text Solution

    |

  17. Explain why friction is necessary to make the disc in Fig. 7.41 roll i...

    Text Solution

    |

  18. A solid disc and a ring, both of radius 10 cm are placed on a horizont...

    Text Solution

    |

  19. A cylinder of mass 10 kg and radius 15 cm is rolling perfectly on a pl...

    Text Solution

    |

  20. Separation of Motion of a system of particles into motion of the centr...

    Text Solution

    |