A 1 kg rock is suspended by a massless string from one end of a meter stick at the 0 cm mark. What is the mass m suspended from the meter st

Question

A 1 kg rock is suspended by a massless string from one end of a meter stick at the 0 cm mark. What is the mass m suspended from the meter stick at the 75 cm mark if the system is balanced?

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Ngọc Khuê 3 weeks 2021-09-03T14:00:50+00:00 1 Answers 0 views 0

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    2021-09-03T14:02:12+00:00

    Answer:

    2 kg

    Explanation:

    Note: For the meter stick to be balanced,

    Sum of clock wise moment must be equal to sum of anti clock wise moment

    Wd = W’d’ ……………. Equation 1

    Where W = weight of the rock, d = distance of the meter stick from the point of support, W’ = weight of the that must be suspended for the meter stick to be balanced, d’ = distance of the mass to the point of support.

    make W’ the subject of the equation

    W’ = Wd/d’…………… Equation 2

    Taking our moment about the support,

    Given: W = mg =  1 ×9.8 = 9.8 N, d = 50 cm, d’ = (75-50) = 25 cm

    Substitute into equation 2

    W’ = 9.8(50)/25

    W’ = 19.6 N.

    But,

    m = W’/g

    m = 19.6/9.8

    m = 2 kg.

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