Question

a uniform ruler can be balanced at 29cm.
Find the mass of the half metre rule​

Answer 1

Appropriate Question :

A uniform half metre rule can be balanced at the 29.0 cm mark when a mass 20g is hung from its one end . Find the mass of the half metre rule.

AnswEr :

• Mass of the half metre rule is 105 g.

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Given :

• Rule can be balanced at 25 cm.

• Mass of the body = 20 g.

To Find :

• Mass of the half metre rule = ?

Solution :

Let us assume that the mass of the half metre rule be x .

Accordingly, the 25 cm marks as centre of gravity!!

So,

Anticlockwise moment = x × 4

Clockwise moment = 20 × 21

According to the principle of moments in equilibrium,

Anticlockwise Moment = Clockwise Moment

which means,

➝ 4x = 20 × 21

➝ 4x = 420

➝ x = 420/4

➝ x = 105 g

$\therefore$ The mass of the half metre rule is 105 g.

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Do you know ?

• Principle of Moments states that :

• When a body or an object is balanced, the total clockwise moment about a point is equal to the total anticlockwise moment about that same point.

• Formula used :

• Moment = F × Perpendicular distance .

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