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Question
State the principle of moments. A meter scale is pivoted at 30 cm mark and it is in equilibrium when a mass of 40 g is suspended from 10 cm mark. Calculate the mass of the ruler.
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Solution
Principle of moments : If a body is in equilibrium under the action of number of force, then the sum of clockwise moments is equal to the sum of anticlockwise moments.
Sum of clockwise moments = sum of anticlockwise moments
40 x 20 cm = mass of scale x 30 cm
or Mass of scale = `800/30` = 26.7 g
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