1. What is the difference between mass and weight?

The weight of an object is the force exerted on the object by gravity.

The mass of an object is the same whereever it is, whereas its weight would vary according to its position.

e.g. An object would have a slightly different weight if it was on the top of Mt Everest than it would if it was at sea level.

A mass of 1 kilogram is equal to a standard mass of metal kept at Sèvres in France. A mass of 1 gram is defined as one thousandth of this weight.

2. What system does the United States use for measuring weight and mass?

The United States uses the IMPERIAL system for measuring weight.

The units in this system include: ounces (symbol oz) pounds (symbol lb), stones, hundredweight (symbol cwt) and tons.

1 lb = 16 oz
1 stone = 14 lb
1 cwt = 112 lb
1 ton = 20 cwt

It would be very expensive for the US to change to metric units.

3. How do you convert between the units in the metric system and the imperial system?

The conversion factor is 1 kg = 2.24 lb.

e.g. 4 kg = 4 x 2.24 lb = 8.96 lb.