Menu
Home / ECE / Exam Questions Paper :: Discussion

Discussion :: Exam Questions Paper

  1. Find the electric charge required on the earth and moon to balance their gravitational attraction if the charge on the earth is 10 times that on the moon.

    2. A.
    1.73 TC
    B.
    17.3 GC
    C.
    17.3 TC
    D.
    1.73 GC

    View Answer

    Workspace

    View Answer

    Answer : Option C

    Explanation :

    Using law of gravitations, the force between the two point masses is F =

    M1 = mass of moon = 6.7 x 1022 Kg

    M2 = mass of earth = 6 x 1024 Kg

    r = distance between masses = 380 mm

    G = universal gravitational constant = 6.7 x 10-11 Nm2/Kg2

    Let Q1 and Q2 be the charge on moon and earth respectively. Now the gravitational force must be balanced by the force of repulsion

    Q1Q2 = 4pε0M1M2G

    but Q2 = 10Q1

    = 10 x 4pω0M1M2G

    ∴ Q2 = 173 x 1012

    Q1 = 17.3 x 1012 C

    Q1 = 17.3 TC.

Write your comments here:

Be The First To Comment