Hello there!

show your work and explain your answer. i don't just need the answer, i also want to know how to solve this kind of problems.

you : )

In the first answer, Paul James is kind of on the right track, 
but the problem is the CUBE of the way he describes it.

I thought about it for the past few hours, trying to come up with
the best way to explain it.  I think I can do it, and I hope it's clear.

Look at it this way:

In the REAL bridge, the volume of a little piece is

                  V = (Length) x (Width) x (Height) .

Whatever that volume is, it'll have 'V' units of steel in it,
and its weight will be 'V' units of weight.

Now, the engineers come along and build a scale model of the bridge.
The scale is  1:100 .
The "scale" always means the ratio of the LINEAR DIMENSIONS.
So that same little piece of the scale model will have

           length  =  1/100 of the REAL length
           width   =  1/100 of the REAL width
           height  =  1/100 of the REAL height .

The volume of the little piece will be

               v  =  (0.01 L) x (0.01 W) x (0.01 H)

  That's           (L · W · H) x (0.01 · 0.01 · 0.01)

                    =      V          x     (0.000001) .

                    =    one millionth of the volume of the real bridge !

The first answer said that if the scale is 1/100 , then the model
has  1/100  of the weight of the full-size bridge.  That's not true.

==>  If the scale is  1/100 , then the model has  (1/100)³
of the weight of the full-size bridge.  That's one millionth.

If the model weighs 50 Newtons, then the real full-size bridge
weighs 50 million Newtons.

Looking at it the other way ... If you scale the model down by 100, 
you scale the volume and weight down by (100)³  =  one million.

So the answer to ' b ' is: No!  The defense is wrong. It does not hold water !

At that scale, you could probably build the model out of cardboard and Kleenex,
and it would be stronger than the full-size structure built with steel !

Here's a general rule for scale models:

... You build a model to some SCALE.

... Each dimension of the model is (1/scale) the size of the original dimension.

... The AREA of the model or any part of it is (1/scale)² the size of
the original area.

... The VOLUME of the model or any part of it is (1/scale)³ the size of
the original volume.   That also goes for the weight, and the amount of
material you'll need to build them with. 

What even is this. where is the question

Hi, your answer is not correct. this is a cumulative