Moment of a 3000N force from a 300kg crate around support A

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John78
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Homework Statement



Calculate the moment of the force exerted by the crate around support A.

Homework Equations



crate = 300 kg
1 kg=10N
300Kg*10=3000N

The Attempt at a Solution



Ra*42 m = 3000N *6m
Ra = 428,57 N

Rb*42 m = 3000N *36m
Rb=2571,42 N


I just want to check whether my working is correct or not.
 
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It is not easy because you have not been told the size of the box!
The moment of the box = weight x distance of centre of mass from A
 
My calculation looks like that

crate = 300 kg
1 kg=10N
300Kg*10=3000N

Ra*42 m = 3000N *6m
Ra = 428,57 N

Rb*42 m = 3000N *36m
Rb=2571,42 N

MA=3000N*6m-2571,42
MA=-89999,64

Ra+Rb=428,57+2571,42=2999,99=3000N!

So the answer is Ra = 428,57 N

Am I right i thinking?
 
if you assume that the cm of the crate is at 6 m from the left, your calculations are good, ecept that you should round them off to about 400N and 2600 N, respectively.