physics

posted by .

1. If our sun shrank in size to become a black hole, using the gravitational force equation, explain why the Earth's orbit would not be affected.
2. Strictly speaking, you weigh a tiny bit less when you are in the lobby of a massive skyscraper than you do at home. Why is this so?
3. Ultimately, the universe may expand without limit, or it may coast to a stop, or it may turn around and collapse to a "big crunch." What is the single most important quantity that will determine which of these fates is in store for the universe?
4. Which requires more fuel - a rocket going from the Earth to the moon or a rocket coming from the moon to the Earth?
I know more fuel is required to go from the earth to the moon but why?

  • physics -

    1. The "gravitational force equation" depends only upon the mass of the central body and the distance from it. The size of the body makes no difference.

    2. There is a lot of mass above you pulling you away fromthe center of the Earth.

    3. The rate of expansion of the universe (Hubble constant) and the density are equally important. See http://en.wikipedia.org/wiki/Critical_density
    The apparent acceleration of the rate of expansion is not understood, not are the roles of dark energy and dark matter. We really cannot make predictions at this time.
    4. Getting to the moon requires much more energy for two reasons:
    (a) Going there, you need to take extra supplies necesary for life support and getting back again.
    (b) The atmosphere of the Earth provides most of the deceleration necessary to land on earth safely, with heat shields, parachutes or lifting-body airplane shapes like Space Shuttle.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. physics (check my answers)

    When the nuclear fuel in the sun is gone, the sun will collapse to a a. black hole b. white dwarf c. supernova d. neutron star My answer: I think its a black hole. If the mass of the Earth were suddenly doubled while the radius was …
  2. Physics

    X-ray pulses from Cygnus X-1, a celestial x- ray source, have been recorded during high- altitude rocket flights. The signals can be interpreted as originating when a blob of ion- ized matter orbits a black hole with a period of 7.84 …
  3. physics question

    A spacecraft in the shape of a long cylinder has a length of 100 m, and its mass with occupants is 1660 kg. It has strayed too close to a black hole having a mass 103 times that of the Sun (Msun = 1.99 x 1030 kg). The nose of the spacecraft …
  4. physics

    Strictly speaking, you weigh a tiny bit less when you are in the lobby of a massive skyscraper than you do at home. Why is this so?
  5. Physics

    Consider the earth following its nearly circular orbit about the sun. The earth has mass 5.98*10^24 and the sun has mass 1.99*10^30. They are separated, center to center, by r=150 million k. What is the size of the gravitational force …
  6. physics

    If the Sun shrank to the size of a black hole without losing any mass, what would happen to Earth's orbit?
  7. Physics

    The Hubble Space Telescope (HST) has recorded evidence of a black hole at the center of the M87 galaxy. Using Doppler data, it's been measured that matter is orbiting the center of this galaxy at an orbital speed of 7.5x10 5 m/s, out …
  8. Physics

    Use the following numbers for this question. MEarth 5.98e+24 kg MJupiter 1.9e+27 kg MSun 2e+30 kg Earth-Sun distance 150000000000 m Jupiter-Sun distance 778000000000 m rE 6380000 m rJ 69000000 m G = 6.67e-11 Nm2kg-2 the acceleration …
  9. Physics

    Calculate the percentage of Earth’s gravitational force on the ISS astronauts while orbiting at an altitude of 248 miles above Earth’s surface. To do this, compare the gravitational force on an orbiting astronaut to the force on …
  10. Physics

    Consider the earth following its nearly circular orbit (dashed curve) about the sun.(Figure 2) The earth has mass mearth=5.98×1024kg and the sun has mass msun=1.99×1030kg. They are separated, center to center, by r=93millionmiles=150millionkm. …

More Similar Questions