# HELP! Simple center of Gravity problem

#### Rha1828

2) A Uniform Boars has a mass of 1.5kg and length of 100cm, Note the Weight is negligible.

A) Where should it be supported so that it will balance a 10g mass places at an end, a 60kg mass on the other end, and a 40kg mass placed 30 cm to the 10g mass?

The answer should be 0.511m

a. First you need to convert all g to kg and cm to m

Therefore,

(10g)(1X10-3kg1g) = 0,010kg

(40g)(1X10-3kg/1g) = 0.040kg

(60g)(1X10-3kg/1g) = 0.060kg

(30cm)(1X10-2m/1cm) = 0.30m

(100cm)(1x10-2m/1cm) = 1.0m

(0cm)(1x10-2m/1cm)= 0 m

Using the center of mass equation you get

Xcg = W1X1 + W2X2 + W3X3 / W1 + W2 + W3
0A

Therefore,

Xcg = (0.010kg)(0m) + (0.060kg)(1.0m) + (0.040kg)(0.30) / (0.010kg) + (0.060kg) + (0.040kg)

= 0.0720kg.m / 0.110 kg

= 0.645 m

I am not sure where I went wrong and why I have a higher number then the answer. Any help would be great!

thank you!!!

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#### LowlyPion

Homework Helper
Sorry, I don't understand your units. What are they g's or kg? They looked mixed in your use of them.

Also the mass of the board is not insignificant. Is this another typo?

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