Plum line is used when ever a straight line is needed, especially when building walls. And usually is made of lead, because of its small volume and high density.

Matter can be defined as anything that occupies space and has mass. We should also understand that no two objects can occupy the same space at the same time. You know that when you take a bath in a tub, the water rises, a certain amount.

Now, let me relate an ancient story, as portrayed on the Boob Tube, many years ago. There was this king, and he had commissioned this elaborate crown to made for him. So, this one gold smith got this commission. When the crown was completed and presented to the king, the king was delighted with the magnificence of the crown. But he suspected something was amiss, how this suspicion got into his mind, is not clear. The jest of the suspicion was, that all was not as it appeared to be, the gold that the king had provided to gold smith, was not all used to make the crown. Now the crown had the same weight as the gold that was given to the gold smith. So how was the king going to solve this problem, with out destroying the crown in the process. It just so happened that the king had as his friend a remarkable man, named Archimedes, who quite often would undertake these unusual assignments. The king presented his problem to Archemedes, he felt that if any body could resolve this dilemma it would be Archemedes. Now, Archemedes spent hours on the problem, and then one day, as he was taking a bath, the thought came to him. That bodies in water weighed less, maybe large rocks were used to heat water in the bath, and they also weighed less, in water. Conducting an experiment between rocks and other objects such as lead or may be some other metal, he noticed that an object can have the same weight, but it would displace a different volume of water. He determined that density would result when the mass of the object would be divided by the volume that it displaced. The way to measure the volume; was fill a container to the brim and measure the overflow of water with a smaller container. And thus he was able to determine that pure gold had a higher density then any other metal. He then had taken the weight of the crown and the volume it displaced, and compared with the weight of known pure gold and the volume it displaced, and that is how the gold smith lost his head, for trying to cheat the king. I guess an appropriate moral to the story would be, quite while you are ahead.

History has it, that Archimedes got his idea while he was taking a bath !

Density then is defined as the mass of the object divided by its volume:

	Mass
Density    =	-----------
	Volume

Since, water is easily purified, it was considered for a standard in measurement. Such that 1 cubic centimeter would be equal to one milliliter, and in turn equal to one gram.

Then applying the to above formula, then the Density of water is equal to 1 gram / ml .

And since water produces a buoyant force upward of one gram for every millimeter of water displaced, we then can find the Density of a submerged object simply by dividing the mass of the object by the volume it displaces.

Now, the objects that you found the approximate weight for, in 'First Class Lever' which in our case were 1 oz., 2 oz., 3 oz., and a 4 oz., lead weights, we are now going to find the Density for them.

NOTE OF CHANGE:

Since the maximum weight, that can be measured with the SBB accurately is about 26 grams, and one once weight of lead, weighs about 28 grams. You can see the problem. Now, you can carry out the experiment with the 'First Class Lever' or I would suggest that you use smaller quantities of lead and use the SBB. Replacing the 1 oz, 2 oz, and so on lead weights, with fishing lead split shot. So that the 1 oz weight would be replaced with a 1 split shot, and the 2 oz weight would be replaced with the 2 split shots until you get to the 4 oz weight which would be replaced with 4 split shots. Now, how to attach the split shot, using the same length of monofilament on both sides, just crimp the split shot to the end of the monofilament. I would suggest that you use a separate monofilament for each split hot. You have to remember to add the same length of monofilament to the other side as well.

(CAUTION ** LEAD IS TOXIC TO YOUR HEALTH, SO BE SURE TO WASH YOUR HANDS WITH SOAP AND WATER AFTER HANDLING THE LEAD WEIGHTS!! )

OBJECT: To find the Density of Lead ( whose symbol is Pb ), to gain experience in weighing objects.

MATERIALS:

Lead weights, SBB, a one gallon plastic container, ( simply remove the spout of the container, but leave the handle attached. ), water, very thin fishing line ( monofilament ), or you can buy monofilament thread, at the sewing store.

PROCEDURE: OBSERVATION:

DENSITY OF LEAD Pb

Object	Weight in air	Weight in water	Loss of weight	Density
1 oz. Lead
2 oz. Lead
3 oz. Lead
4 oz Lead
				Average for Pb

Since, we do not have a graduate cylinder, for finding the volume of each object. We know that an object, will weigh one gram less for every millimeter or cubic centimeter of water it displaces, so we are finding the volume indirectly, and since our balance is far more accurate then any graduate cylinder, we then can use the loss of weight as the volume.

1. Zero balance your SBB, and find the exact weight of each object that you are working with, and record it in the table.

2. Now, repeat the above procedure, but this time obtain a gallon plastic container, with the top removed, but leave the handle attached, while removing the spout. Fill half way with water, and place it on the floor near the table with the SBB.

3. Obtain very thin thread, or mono filament thread, and tie a three foot section to each object that you are going to weigh. Technically speaking you should place the same length of thread in the right cup as well, to off set the thread on the Left.

4. Next, move your SBB to the edge of the table where you are working, place several heavy books at the base of SBB, so that it won't tip over. ( Or you can buy a twenty cent piece plastic coupler (1/2 inch pvc ), and add a foot to the length of the stand, makes working with SBB a lot easier ). Check to see if the SBB is zero balanced. Approximate the distance to the water. Make a loop at the end of the thread, gently slip the loop on to the paper clip supporting the plastic cup, on the left side. Gently slip the object that you are weighing into the plastic container, and record it's weight in the table ( chart ).

5. If you find that the thread is to long, you can shorten it by making a knotted loop in the middle of the thread, but first detach it from the SBB, so the SBB wont tilt over.

6. Repeat the above procedure for each object, and record the weight.

7. Get your calculator, or use the one on Windows 95 or 98 and compute the results, and record them .

8. Loss of weight, would be the amount of millimeters, that the object displaced. Use this value as millimeters for your formula.

9. To find your average Density for Lead ( Pb ), add up your four values and divide by the number of trials.

QUESTIONS:

1. What is the formula for density ?

2. Explain the difference between mass and weight .

3. What are the units for density ?

4. Explain the difference between qualitative and qualitative properties of substance.

5. Using water for an example, make a chart to contrast the main characteristics of the three states of matter.

6. Look up Archimedes and find out what other accomplishments he is credited with.

7. What is the relationship between 1 gram of water and 1 millimeter of water at 4° Celsius ?