Question

Here's a question.....!!
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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.
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Answer 1

Answer:

Refer to the Attachment !!!!

Hope it Helps !!!!

Answer 2

Answer:

Let the weight of the half metre rule be x gf and it acts at the 25 cm mark (centre of gravity).

Now,

★ Acticlockwise moment = x * 4

★ Clockwise moment = 20 * 21

In equilibrium,

Anticlockwise moment = Clockwise moment

=> 4x = 20*21

=> x = 105 gf.

Thus, the weight of the metre rule is 105 gf.

★ We know, one gf is the force acting on the body of mass 1 grams, thus mass of the body is 105 grams.