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8 July, 04:12

1) The moon has a mass of 7.4 * 1022 kg and completes an orbit of radius 3.8 * 108 m about every 28 days. The Earth has a mass of 6 * 1024 kg and completes an orbit of radius 1.5 * 1011 m every year. What is the speed of the Moon in its orbit? Answer in units of m/s.

2) What is the kinetic energy of the Moon in orbit?

Answer in units of J.

3. What is the kinetic energy of the Earth? Answer in units of J.

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Answers (2)
  1. 8 July, 04:28
    0
    What is the speed of the Moon in its orbit? Answer in units of m / s.

    By definition we have that the speed in a circular movement is given by:

    v = w * r

    We then have to replace the values:

    v = ((2 * pi) / (28 * (24/1) * (3600/1))) * (3.8 * 10 ^ 8)

    v = 986.94 m / s

    2) What is the kinetic energy of the Moon in orbit? Answer in units of J.

    By definition, the kinetic energy is given by:

    K = (1/2) * (m) * (V ^ 2)

    Where,

    m: mass

    V: speed

    Substituting the values we have:

    K = (1/2) * (7.4 * 10 ^ 22) * ((986.94) ^ 2)

    K = 3.60E + 28 J

    3. What is the kinetic energy of the Earth? Answer in units of J.

    First we must find the speed of the earth:

    v = ((2 * pi) / ((1) * (365/1) * (24/1) * (3600/1))) * (1.5 * 10 ^ 11)

    v = 29886 m / s

    By definition, the kinetic energy is given by:

    K = (1/2) * (m) * (V ^ 2)

    Where,

    m: mass

    V: speed

    Substituting the values we have:

    K = (1/2) * (6 * 10 ^ 24) * ((29886) ^ 2)

    K = 2.67E + 33 J
  2. 8 July, 04:39
    0
    Mass of the moon Mm = 7.4 Ă - 10^22 kg

    Moon orbital radius Rm = 3.8 Ă - 10^8 m

    Time Tm = 28 days = 2.419 x 10^6

    Mass of the Earth Me = 6 Ă - 10^24 kg

    Earth orbital radius Re = 1.5 Ă - 10^11 m

    Time Te = 365 days = 3.154 x 10^7

    Length of Moon orbit Lm = 2 x pi x Rm = 2 x 3.14 x 3.8 Ă - 10^8 m = 23.86 x

    10^8 m

    Moon orbital velocity Vm = Lm / Tm = 23.86 x 10^8 m / 2.419 x 10^6 = 986.5 m/s

    Kinetic Energy of the Moon = 1/2 x Mm x Vm^2 = 0.5 x 7.4 Ă - 10^22 x 986.5^2

    Kinetic Energy of the Moon = 36 x 10^27 J

    Length of earth orbit Le = 2 x pi x Re = 2 x 3.14 x 1.5 Ă - 10^11 = 9.42 x 10^11 m

    Earth orbital Velocity Ve = Lm / Tm = 9.42 x 10^11 / 3.154 x 10^7 = 29866 m/s

    Kinetic Energy of the Earth = 1/2 x Me x Ve^2 = 0.5 x 6 Ă - 10^24 x 29866^2

    Kinetic Energy of the Earth = 26.76 x 10^32 J
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