Question

A box weighs 81 times more than it did before i enlarged it. How much did i enlarge the box?

Answer 1

Mass of any physical quantity is given by

Mass = Volume * density

as the box remains of the same material we can say that the density will also be same in both the cases before the enlargement and after the enlargement.

therefore the mass of the box is solely depends upon the volume of the box

Assuming the box is of cube in nature .

Suppose the side of the box initially is a units and after the enlargement it becomes a+x units (we increases x units in each side)

thus according to the question

or

it is a cubical equaiton in x , thus after solving it we get the value of x in terms of a which is

This is the enlargement you have done to each side in terms of its initial length