How much does a 5 pound bag of flour weigh in newtons?

OK.  This is just a conversion from pounds to Newtons on Earth.

You could go look up the weight of a kilogram of mass in pounds,
but you still would not know how many newtons that is. I'll give it
to you in just a second.

Here is how I think you have to do it:

The weight of any mass in newtons = (mass) x (acceleration of gravity).

Acceleration of gravity on Earth is 9.81 m/s² .

So the weight of 1 kilogram of mass is (1) x (9.81) = 9.81 newtons.

When you look up the weight of a kilogram, it says  " 2.2 pounds ".

Now you have what you need !    2.2 pounds = 9.81 newtons .

You can use a proportion for the bag of flour:

         9.81 newtons / 2.2 pounds  =  'x' newtons / 5 pounds  .

Now you just solve the proportion for 'x' ... cross multiply and all that stuff.

I hate to just throw an answer at you and have you run away with it,
because then you won't know how to solve the next one.  So I'll just
stop here.  I know you can finish it off with the proportion.

╔═⋄═◇═◈═❖═✧═☆═✧═❖═◈═◇═⋄╗✧   ok, now this, is epic.╚═⋄═◇═◈═❖═✧═☆═✧═❖═◈═◇═⋄╝

127 millimeters is the answer