An object weighs 80 N on earth surface...?

The same object will weigh 20 N at an height from the surface of the earth?

a)R/4

b)2R

c)R/2

d)R

Please explain how???????? :(

3 Answers

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  • Anonymous
    6 years ago
    Best Answer

    mass remains same every where

    so mg=80

    m=8.16 kg

    when the object weigh 20 N

    mg'=20

    g'=20/8.16=2.451 m/s^2

    now

    F=GMm/r^2 [at surface]

    mg =GMm/r^2

    g=GM/r^2

    F'=GMm/(r+h)^2 [at height h]

    mg'=GMm/(r+h)^2

    g'=GM/(r+h)^2

    g'/g=r^2/(r+h)^2

    2.451/9.8=(6400/(6400+h))^2

    0.25=(6400/(6400+h))^2

    6400/6400+h=0.5

    6400=3200+0.5h

    h=6400 km=r

    so the answer is d

  • Steve
    Lv 7
    6 years ago

    Weight is inversely proportional to the square of the distance R from the center of the earth.

    Ergo, if H = R → R' = 2R, g' = gR²/(2R)² = 0.25g

    80*0.25 = 20

    (d)

  • 3 years ago

    3.seventy 5 w=ma here, w1,w2 is weight of merchandise in earth and mars a1,a2 is acceleration in earth and mars mass would be comparable w1=m(a1) 350=m(9.5) =>m=35.seventy one w2=m(a2) 134=35.seventy one(a2) =>a2=3.seventy 5 subsequently C.3.seventy 5 is actual answer

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