The strength of a beam varies inversely as the cube of its length. The beam 3m long can support 920 kg. how much can a similar 7m beam ?

Question

hba · Answer

This is not the physics portion :/

hba · Answer

Let me link you- http://openstudy.com/study#/groups/Physics

hba · Answer

Close both os them up now.

tkhunny · Answer

This is a fine algebra problem.

Strength Varies inversely with Length MEANS 

$Strength = \dfrac{k}{Length}$

We are given

$920\;kg = \dfrac{k}{3\;m}$

Solve for 'k' and you are almost done.