11. | The escape velocity from the earth’s surface is 11 km/sec. A certain planet has a radius twice that of the earth but its mean density is the same as that of the earth. The value of the escape velocity from this planet would be (a) 22 km/sec (b) 11 km/sec (c) 5.5 km/sec (d) 16.5 km/sec |

12. | The escape velocity from earth is 11.2 km per sec. If a body is to be projected in a direction making an angle 45° to the vertical, then the escape velocity is (a) 11.2 ´ 2 km/sec (b) 11.2 km/sec (c) 11.2 ´ (d) 11.2 ´ |

13. | What would be the duration of the year if the distance between the earth and the sun gets doubled? (a) 1032 days (b) 129 days (c) 365 days (d) 730 days |

14. | If escape velocity from the earth’s surface is 11.2 km/sec. then escape velocity from a planet of mass same as that of earth but radius one fourth as that of earth is (a) 11.2 km/sec (b) 22.4 km/sec (c) 5.65 km/sec (d) 44.8 km/sec |

15. | A thin uniform, circular ring is rolling down an inclined plane of inclination 30° without slipping. Its linear acceleration along the inclined plane will be (a) g/2 (b) g/3 (c) g/4 (d) 2g/3 |

16. | A artificial satellite moving in a circular orbit around the earth has a total (kinetic + potential) energy E (a) 2E (b) E (c) 1.5 E (d) -E |

17. | The distance between centre of the earth and moon is 384000 km. If the mass of the earth is 6 ´ 10 (a) 1 km/sec (b) 4 km/sec (c) 8 km/sec (d) 11.2 km/sec |

18. | When body is raised to a height equal to radius of earth, the P.E. change is (a) MgR (b) (c) 2 MgR (d) none of these |

19. | A planet has twice the radius but the mean density is 1/4 (a) 3 : 1 (b) 1 : 2 (c) 1 : 1 (d) 2 : 1 |

20. | The masses of two planets are in the ratio 1 : 2. Their radii are in the ratio 1 : 2. The acceleration due to gravity on the planets are in the ratio. (a) 1 : 2 (b) 2 : 1 (c) 3 : 5 (d) 5 : 3 |

Answer

11. Ans.: (a)

12. Ans.: (b)

13. Ans.: (a)

14. Ans.: (b)

15. Ans.: (c)

16. Ans.: (a)

17. Ans.: (a)

18. Ans.: (b)

19. Ans.: (c)

20. Ans.: (a)