Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page.

High school physics question. Can't figure it out. At this point i need help?

satellites orbit earth at distance of 42,000,000 m from earths center. Their angular velocity at this height is the same as the rotation of the earth, So they appear stationary at certain locations in the sky. what is the period of the satellite? The mass of the earth is 5.97x10^24 kg

2 Answers

Relevance
  • 4 years ago

    The period is the time for the satellite to move a distance that is equal to the circumference of a circle. Since the satellite is moving at a constant speed, the centripetal force is equal to the Universal gravitational force.

    m * v^2 ÷ r = G * M * m ÷ r^2

    v = √(G * M ÷ r

    G * m = 6.67 * 10^-11 * 5.97 * 10^24 = 3.98199 * 10^14

    r = 4.2 * 10^7

    v = √(3.98199 * 10^14 ÷ 4.2 * 10^7)

    This is approximately 3,079 m/s

    C = 2 * π * 4.2 * 10^7 = π * 8.4 * 10^7 meters

    To determine the time for the satellite to orbit the earth, divide this distance by its velocity.

    t = π * 8.4 * 10^7 ÷ √(3.98199 * 10^14 ÷ 4.2 * 10^7)

    This is approximately 85,704.5 seconds

    One day = 24 hours

    One hour = 3600 seconds

    One day = 24 * 3600 = 86,400 seconds.

    If we round by answer, it will be one day. This proves that the satellite and earth have the same angular velocity.

  • 4 years ago

    24 hours ( approximately)

    If it appears stationary then it must turn at the same rate that the earth does.

    To be quite precise the earth turns one full turn in slightly less than 24 hours.

    It must turn a little more than a full turn so that it faces the sun at the same moment each day.

    Hence 24 hours = T * ( 1+1/365.3 )

    T = 24 / ( 1+1/365.3) = 23.93 hours

    or 8.6 * 10 ^ 4 s

Still have questions? Get your answers by asking now.