What is the mass of the ruler moments? (Answer: 127.04g)

[calculator20]

Homework Statement

Trying to answer the question shown in the picture below. I have to deduce the mass of the ruler.

Relevant Equations

Assuming it’s a moments problem

The answer is 127.04g. I’m getting close but can’t get the answer.

Using 9.81 for gravity, the force where the balance is is 2.10(58146)N

As it is balanced

2.10N x 0.29m = W x 0.50m where 0.50 is the centre of mass

That gives W = 1.22N

= 124.5g?

 

[mjc123]

Is 0.50 m correct for the centre of mass?

 

[jack action]

Did you notice the metre ruler was pivoted at the 1.0 cm mark?

 

[calculator20]

49cm, thank you!