I need help solving this problem

Question

A bar of silver weighs 0.800kg; what is the weight of at in grams , milligrams and pounds? 1lb= 454g

Answer 1

Dimensional analysis:

0.800 kg x 1000 g/kg = 800 g = 8.00x10² g

0.800 kg x 1000 g/kg x 1000 mg/g = 8.00x10⁵ mg

0.800 kg x 1000 g/kg x 1 lb/454 g = 1.76 lb

Answer 2

Hi, Yesenia,

A bar of silver weighs 0.800kg.

Use conversion factors. I have a document that describes these more thoroughly at https://drive.google.com/file/d/1DsD1Wa7KirIn-x3jgtQWQX6BeyjeAKen/view?usp=sharing

0.800kg * 1000g/kg = 800g

The 1000g/1kg is a conversion factor that simply says 1000g = 1kg, but written so that the kg is on the bottom and g on the top. A conversion factor is numerically equal to "1," since the numerator is equal to the dem=nominator. Thus, I can multiply it against anything, and the answer will be correct. The units change, however, and can be cancelled to leave us just grams, as we have here.

I could invert the constant to 1kg/1000g if I wanted to convert g into kg. That's the fun part of working with conversion factors.

There are 1,000,000 mg/kg and 1 lb/454 g

0.800kg * 1,000,000 mg/kg = 800,000 mg

0.800kg * 1,000 g/kg * 1lb/454 g = the answer to the last problem.

Note how the units all cancel in each of the problems. I used two conversions in the last to get an answer in lbs, See how the units cancel.

Have fun,

Bob