Weight
In the imperial system
Pounds
•The pound as a unit of weight dates back at least
as far as the time of the Romans
•the symbol for one pound is 1 lb. This symbol is
an abbreviation of the Latin word libra—the word
for a set of scales used for weighing.
One pound is
defined as exactly
0.453 592 37 kg.
Scales
•a set of scales is considered to be any instrument that
measures weight (mass).
•An instrument that measures weight does not have to
be made up of two pans connected to a bar
•For example, bathroom scales
ounce (oz)
There are 16 oz in 1 lb. 1 lb = 16 oz
The Roman pound was divided into 12 parts. The Latin
word uncia for “twelfth part,” as you will recall, gave the
word inch. It also gives the English word ounce.
The troy pound, used for precious metals, such as gold
and silver, still has 12 ounces. However, the modern
pound commonly used for weight (mass) is divided into
16 ounces!
Nutritionists recommend active teenage girls eat 5 oz of
protein each day. How many pounds of protein would this
recommendation be over a 30-day month?
Krysta’s baby was 6 lb 7 oz when she was born. Altogether,
how many ounces did the newborn weigh?
Large Masses
•in the metric system for large masses we measure in
tonnes. 1 t = 1000 kg
•In the imperial system, large weights such as the weight of
sand being hauled in a truck, is measured in tons. There are
short tons and long tons.
1 ton = 2000 lb
1 short ton = 2000 lb
1 long ton = 2240 lb
The British defined the ton
as equal to 160 stone when
they considered the stone as
the basic unit of weight. One
stone equals 14 lb.
Therefore, the British ton,
now also known as the long
ton, is equal to 2240 lb.
Since 1 kg is about 2.2 lb, what would an approximation of
the metric tonne be in pounds? Which is a metric tonne
closer to—a short ton or a long ton?
Mr. Watnee hauls gravel. He estimates that 1 yd3 weighs 3000
lb. How many tons (short) would a 5-yd3 load of gravel
weigh?
Sergey loaded 200 bushels of wheat into the box of his truck.
The grain weighed 5.2 tons (short). How many pounds did
each bushel of wheat weigh?
Mass Conversions
Imperial
Metric
1 oz
28.3495 g
1 lb
0.4536 kg
1 ton (short) = 2000 lb
__________ t
1 ton (long) = 2240 lb
__________ t
Mass Conversions
Metric Imperial
1g
__________ oz
1 kg
__________ lb
1t
__________ ton (short)
1t
__________ ton (long)
Gabi weighs 116 lb. What is her mass to the nearest
kilogram?
Apples cost $0.79 per pound. What is their cost per kilogram?
Round your answer to the nearest cent.
How much does 1 gal of water weigh in pounds if 1 L of water
has a mass of 1 kg? Round your answer to the nearest pound.
Connie is planning to lay a concrete driveway 60 ft long, 15 ft
wide, and 4 in thick. If 1 yd3 of concrete weighs 4000 lb, how
many tons of concrete are needed for the driveway? Round
your answer to 1 decimal place.