Thursday, November 5, 2009
How To Measure Volume Of Liquid
The liter (L) is a metric unit for measuring the volume of a liquid. The liter is divided into 1000 units called milliliters. The milliliter (abbreviated mL) is 1/1000th of a liter. Use a plastic syringe with marks . Observe the surface of the waterwhen you fill the syringe with water. Is the surface of the water curved or flat?The slightly curved surface is called the meniscus.Usually the surface of water in a glassgraduated cylinder is curved. If the cylinderis plastic, the meniscus is flat. Observe if the surface of water in the syringe is curved or flat. An instrument such as a syringe withregular markings to measure volume is called agraduated cylinder.
The correct way to read the volume of a liquid is to hold the graduated cylinder with the meniscus at eye level as shown in the drawing. Always read the level of the liquid at the bottom of the meniscus.
The correct way to read the volume of a liquid is to hold the graduated cylinder with the meniscus at eye level as shown in the drawing. Always read the level of the liquid at the bottom of the meniscus.
Measuring the volume of water with a graduated cylinder is more accurate .
Wednesday, November 4, 2009
Mesuaring volume of liquids
Today we're going to learn how to measure liquids. The result of the measuring is called "volume. "The volume of a liquid can be measured by using any small container to fill a larger one, or, if you have a small amount to measure, by pouring into smaller containers until you find one that exactly holds all the liquid. Each time a container is filled, that is one unit of measure. Remember, a "unit" can be any size; it is called a "unit" because it is a "thing" all by itself. We will begin by collecting some different kinds of containers that will hold liquids. We have paper cups, three sizes of drinking glasses, an emptymargarine tub, a kettle, a teacup, a coffee mug, a vase, and a few other containers. Let's arrange them in order of the amount of water we think they will hold; have the smallest container on the left, and the largest one on the right.That lovely bud vase is much taller than the big drinking glass; let's put it to the right of the glass.
The first test will show us how good we are at estimating the volume of an amount of water. First, we'll fill the small drinking glass, all the way to the brim, with our blue water. Look at it closely, and decide how high the water would be if it were poured into some of the other containers. You could make lists; of containers that are the same type, number them "#1, #2, #3," according to their size, with the smallest one being "#1."
One of you thinks that the water would reach half-way to the top of the bud vase, because the bud vase is twice as tall as the glass. Whoops! The bud vase is full, even though I only poured out half the water from the glass! How can that be? Do you think it could be because the bud vase is skinny and the glass is fat? We will have to move the bud vase to a place in the line where we think it is close to the same size as a much smaller container.
This time we'll get a small container and estimate how many times we could fill it from the glass. The thimble would take too much time, so we'll try glass #1, which is the size used for serving juices. It's a lot shorter than the full glass (#3), and I heard somebody say we could fill it two times from the full glass. Right! It is exactly one-half the size of the starting glass. We know that because we filled it once, poured it back into the pail, and filled it again. This drinking glass is about the same height as the teacup and coffee mug. Somebody can try those. Usually, teacups are smaller than coffee mugs, so it would be best to pour the water into the teacup. Now, pour it from the teacup into the coffee mug. Oh, oh! The coffee mug is smaller. Do you suppose that is because it is so much thicker?
What we see from all this is that the size (in volume) of containers is sometimes hard to estimate; that we need to know arithmetic because we sometimes have to figure amounts of liquid; that we have to use our eyes in a critical manner and look at the different aspects of units, such as height, width, and thickness; that liquids have no shape of their own, but take on the shape of their containers; and that containers used for measuring are really handy
Try it yourself.....and belive it....
Sample of container...clik here
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