# Weight and Mass

## Weight and mass are two commonly misunderstood terms in fluid mechanics and mechanics. Weight is the measurement of the gravitational force on an object, while mass is the measurement of the amount of matter in an object.

###### Asked in Science, Units of Measure, Weight and Mass, Atomic Mass

### What instrument measures mass?

Traditionally a balance was used to measure mass. Objects of
known or accepted mass was balanced against another object of
unknown mass. When the balance was level the two pans had the same
mass. The term balance or scales is still used even though there is
no balance used. The scales were the pans that the objects sat
on.
Now electronic balances are used that gauge the mass of the
objects. While you can measure mass with a spring loaded scale, it
is less accurate than a balance as it relies on a spring loaded to
a specific acceleration of gravity for any given mass. A change in
altitude will change the results given on the scale, due to the
actual change in gravitational force (it is small at only about
0.031% error for every kilometer increase in altitude)*. A balance
would experience no such change as the mass of an unknown quantity
is compared to the mass of a known quantity, thus negating any
effects of gravity.
Another instrument that measures mass is an inertial
balance. An inertial balance doesn't require gravity to work,
so it can be used in space. It measures the mass of an object by
attaching it to a spring and seeing how it affects the spring's
period of oscillation.
Very tiny masses can be measured directly (using a
"massometer"). But we normally use scales, which measure weight,
which is directly proportional to mass (a property of matter equal
to its resistance to a change in speed or direction of travel). The
mass of an object is the same everywhere in the universe. Its
weight, however, changes depending upon its location: a bowling
ball has greater weight on the surface of the Earth than it does on
the Moon. Great confusion arises when people interchange units of
weight with units of mass. Scientists, particularly physicists, are
very careful about not using the terms interchangeably, but regular
folks have no choice for practical applications. For example, when
you weigh a regulation ten-pin bowling ball, the scale will tell
you it "weighs" between 4 and 7 (3.63 to 7.27 actually) kilograms,
even though the kilogram is, technically speaking, a unit of mass,
not weight.
You can also measure the mass of an object using a scale, as
long as you factor in the gravitational constant (G). For instance,
in an environment with only 1/2 the gravity of That on earth, you
would have to double the weight displayed on the scale to
determine the actual mass. As an example, 10Kg of lead in a
0.5G environment would only "weigh" 5Kg on a scale...half as much
as on earth, even though its mass is unchanged.

###### Asked in Weight and Mass

### How many pounds are in a kilogram?

One lb is 0.454 kg, so a tad more than 2.
1 kilogram = 2.2 pounds. (2.20462262 to be more
precise).
22 pounds = 10 kilos
The formula to convert kg to lbs
1 kg * 2.2046 lbs
= 2.204622622 lbs
kg and lbs can't be equated, since they're units of different
types of quantities.
The "kg" is a unit of mass, whereas the "lb" is a unit of
force.
On Earth, 1 kg of mass weighs 2.205 pounds. In other places, the
same 1 kg
of mass has a different weight.
Formula: pounds x 0.454 = kilograms

###### Asked in Math and Arithmetic, Units of Measure, Volume, Weight and Mass

### How do you convert litres into pounds?

There is no equivalence.
A pound is a measure of mass. A litre is a measure of volume.
The two measure different things and, according to basic principles
of dimensional analysis, conversion from one to the other is not
valid.
If you are not convinced, consider a litre of air. How many
pounds? Next consider a litre of water. How many pounds?
The masses of equal volumes of the two substances will clearly
be very different.
There is no direct conversion between mass and volume:
You need to know the density of the substance to enable
you to carry out the conversion.
If you can find the density of the substance (grams) then to
convert the amount of litres to pounds:
Convert it to kilograms to maintain the same unit
Multiply the number of kilograms by 2.20462 (pounds/
kilogram)
The result will be the amount of litres of the substance in
kilograms

###### Asked in Units of Measure, Cooking Measurements, Weight and Mass

### How many grams are in a tablespoon?

It depends on what you're measuring.
What's the tablespoon holding? Butter or oregano? Sugar or salt?
Molten lead or feathers?
Grams are a unit of mass (or weight) and a tablespoon is a unit
of volume. Therefore it depends entirely on what you are measuring
-- it depends on the density of the substance. A tablespoon
of lead will be much heavier than a tablespoon of feathers
(although a gram of lead and a gram of feathers weigh exactly the
same!). Similarly, a tablespoon of butter weighs a different number
of grams than a tablespoon of salt.
See the Web Links for a handy automatic conversion
calculator. Just enter the food item, the units you have, and the
units you want... and presto!
For instance (for US tablespoon):
1 tablespoon of water weighs 14.79 grams
1 tablespoon of table salt weighs 18.25 grams
1 tablespoon of butter weighs 14.19 grams
1 tablespoon of oil (canola or soy) weighs 13.62
grams
1 tablespoon of sugar (granulated) weighs 12.5 grams
1 tablespoon of sugar (brown) weighs 13.8 grams
(packed)
Some other useful conversions:
16 tablespoons = 1 cup
3 teaspoons = 1 tablespoon
28.35 grams = 1 dry ounce
1 US tablespoon = 14.7867648 ml

###### Asked in Physics, Math and Arithmetic, Weight and Mass, Gravity

### What is mass divided by weight?

Answer #1:
It's (1) divided by (the acceleration of gravity in the place
where that mass has
that weight):
weight = mass x g (where g is the acceleration due to
gravity)
⇒ mass/weight = mass/(mass x g)
= 1/g
On the earth, g ≈ 9.81 ms-2 ⇒ mass/weight ≈ 1/9.81 ms-2 ≈ 0.102
m-1s2
On the moon, g is approx 1/6 that of the earth, ⇒ mass/weight ≈
6/9.81 ms-2 ≈ 0.612 m-1s2
If the questioner really meant weight divided by mass it gives
the acceleration
due to gravity in that place otherwise I'm not sure of a use of
knowing the
reciprocal of the acceleration due to gravity that the
questioner asked.
=============================
Answer #2:
If you ask a scientist, that's true answer in the sense that a
mass M experiences
a gravitational force Mg and if you measure weight in units of
force (which
nobody does). But anyone else would be surprised to learn that a
mass M (say
10 grams) would have a weight of anything else but M grams (10
grams).
Sometimes expressed as "grams weight" often just grams for
short. If you pick
up a Kilogram, even a scientist would say "its weight is 1
kilogram". The
gravitational force on it is 1g, so if you let it go it will
accelerate at a rate force
over mass, which is g. So the answer depends on your units of
mass and weight.
That's why science lessons tend to avoid use of "weight". In
outer free space
mass would be measured by (say) tension in the string if you
whirl it on the end
of it around your head, but the weight (measured by a spring
balance) would be
zero (precisely as described in the first answer above, with
g=0).
==============================
Answer #2.1:
The problem with discussing mass and weight in the same units,
and the reason that this masked contributor is waging a one-man
battle to make the distinction recognized and acknowledged by users
of this website, is the new problem that
you have now that the space age is here.
As long as we were all irrevocably bound to the Earth, one
kilogram of mass would always weigh one kilogram, if you like it
that way. We could afford to be sloppy about it, with hardly one
out of ten men-on-the-street knowing or caring about the
difference, and nobody ever had a problem with it.
But now that some of us have already slipped these surly bonds
... and among
the general population, the younger you are, the better the
chance that you will
do so one day before you're done ... those who ignored the
distinction begtween
mass and weight all through school, or never even encountered it
there, are
poised to step into an inconvenient pile. Because as soon as you
pack for your
trip to anywhere else away from Earth, and take along your lucky
kilogram,
you're due for a shock when you step out at your destination:
Your kilogram
doesn't "weigh" a kilogram there. It weighs something else. If
you're on the
moon, for example, your kilogram weighs 0.165
kilogram ! That's the
shock I'm trying to avoid, because if you think the straight
dope is too complex
for people to handle now, you haven't seen
anything yet.

###### Asked in Medication and Drugs, Cooking Measurements, Weight and Mass, Cinnamon

### How many grams of cinnamon does a teaspoon hold?

You cannot directly really convert g (a solid measurement) to ml
or teaspoonfuls (a liquid measurement). In an ounce, however, is
30ml or 28.3g. 30 ml is 2 tablespoonfuls, 3 teaspoonfuls in a
tablespoon. I would say it is approximately 5g since there are 5ml
in a teaspoonful and 28.3 and 30 aren't too far apart.