![[IMAGE]](Seesaw.gif)
When this life is over, will it be said of you or me that we have waisted our time and have nothing to show for !
Limited Introductory Notes
To aid the SBB in determining the exact weight, after finding the approximate weight of a large ( or heavy ) objects. This device will be used to basically save time. This " two foot metric ruler " lever will be need in the " Bunsen photo meter " and the " Optical Bench "!
What is energy ?
It is the ability to do work.
Work is accomplished when FORCE acts on an object and the object moves a certain a distance.
What is a lever ? It is a simple machine.
What is a simple machine- a device that helps to accomplish a task with one swift motion.
Now, machines do not save you work, they just make work easier.
Lever is a rigid bar capable of moving around a fixed point. Like the SBB balance that we have constructed. Now the reason why the SBB works is because of the law of the "lever " which basically states that the
RESISTANCE x RESISTANCE DISTANCE = EFFORT x EFFORT DISTANCE .
Now, all distances are measured with respect to the PIVOT POINT, which in fact is our FULCRUM.
R x Rd = E x Ed
Example
If you had two students of different sizes, one individual weighed 75 pounds and the other one weighed 100 pounds; and they went to the play ground and they wanted to use the seesaw. Could they use the seesaw? You know that the seesaw would have to be adjusted, or if it was not the adjustable type, then one student would have to sit closer to the pivot point, if they were going to use the seesaw. Which one would have to sit closer to the pivot point ? That's right the heavier one. If the smaller student sits at about five feet from the fulcrum, how far must the larger student sit, in order to make use of the seesaw ?
100 lbs = Resistance
X distance = Rd or Resistance distance
75 lbs = Effort
5 feet from fulcrum = Ed or Effort distance
Law of the lever states
R x Rd = E x Ed
Rd = X
So, we now have R x X = E x Ed
100 lbs x X = 75 lbs x 5 feet
100 x X = 375 feet
divide booth sided by 100 we get 3.75 feet !
OBJECT :
To construct a functional FIRST CLASS LEVER, and to study and observe how the Law of the Torques works.
MATERIALS :
A two foot section of 1/2 inch pvc pipe, a stand from the SBB project, hack saw, one gallon plastic water or milk container, stapler, and paper hole puncher, 1/2 inch roll of see through tape, photo copy of metric ruler, drill and small size bit, magic marker ( fine point, permanent). A set of standard weights ( see ( Pill containers P1, P2 in SBB) ), paper clips.
PROCEDURE :
Be sure to get your parents to do any cutting or drilling. And don't forget, SAFETY COMES FIRST by wearing your safety goggles.
1. Cut a two foot section of a PVC pipe, using your LS ( Large Sleeve ) to make your circle around the pipe, to guide your cutting. As you did, in making the SBB. Remove your Burrs (See instructions in SBB constructions ).
2. Measure exactly 12 inches from the end, make a mark, slide your LS on to the pipe, and make a circle at the 12 inch mark. Allow time for the circle to dry.
3. Replace the LS with its 6 o'clock, 9 o'clock, 12 o'clock and 3 o'clock markings. ( See making of the LS in the SBB set up.) Make about a 1/4 inch mark on the Circle, at the 9 o'clock and the 3 o'clock, using the guide located on the LS. And label the marks as 9 o'clock and 3 o'clock, with a magic marker.
4. Using your denting nail, and make a good dent at the 9 and 3 o'clock marks. A vice would be useful, but not necessary.
5. Secure your pipe, by using a vice or a home made vice ( see earlier instruction for a home made vice ) Drill a very small hole at the 9 o'clock position, But Do Not Drill Through the pipe. Then repeat the procedure, by drilling at the 3 o'clock position. This will be your PIVOT POINT or your FULCRUM. Remove any burrs.
6. If you made several copies of 12 inch ( a light color) ruler with metric on one side. With scissors cut off the metric side, it should be kept as narrow as possible, it should be about 3/8 of an inch wide. Take this strip, the strip should have about a 1/2 inch blank lead before the metric measurement begins and it should extend to the 30 millimeter point, which means you have to cut off about 5 mm from the end. Obtain a half inch roll of see through tape ( hazy in appearance and you can write over or on it, with a ball point pen) , and cut a sliver of tape, (The sliver would be 1/8 to 1/4 of an inch by the width of the tape ) place the metric strip just above the 9 o'clock position at exactly at the circle mark, such that the hole will be below the metric srtip and ( 0 ) zero or the starting point of the metric strip, should coincide with the circle mark. Now secure the strip with the sliver of tape. Making sure that the strip is fairly straight, secure the other end of the strip, with another sliver of tape. Now check to see, if it is in the right position, using your 1/2 inch roll of see through tape, tape over the centimeter strip. This will serve as a protective shield for the metric strip. See the diagram below !
Now, take the second metric strip, and trim this one, at the 0 mm position and at the 30 mm position. Line up the 30 mm position so it ends up, at exactly at the 0 mm position of the first metric strip. Use slivers of tape to hold it in position, and tape over it.
The result will be a " two foot metric ruler ", try to locate the hole with a straighten paper clip with a right angle bend, at one end. The same one used in the SBB, and push through the tape, so that it will come out at the 3 o'clock position. USE CAUTION, HOLD THE BEAM, SO THAT YOUR FINGERS ARE CLEAR OF THE 3 O'CLOCK HOLE, TO PREVENT ANY INJURY!!!!!
![[IMAGE]](SliverTape.gif)
7. Remove the paper clip, and obtain two plastic strips cut from a one gallon milk or water container. The strips should be five inches long and one inch wide. With a magic marker, draw a line the length of the plastic strips, half an inch from the edge. Make a loop, such that the line is on the out side of the loop, and staple the ends. Take the one loop and place it on the pipe, and squeeze the plastic, so it seems like your squeezing the pipe, when you reach the end and you cannot squeeze it any more, bend the plastic strip over the pipe, first in one direction, then reverse direction. So in effect you are making a fold in the plastic strip. Remove the plastic strip and try to staple the strip as close to the fold that you made, so now if you return the plastic loop it should have a snug fit. Now, you have a plastic loop, with two staples, between the staples, using a paper hole puncher, make a hole between these two staples. Repeat the same procedure with the other plastic loop. Obtain a paper clip and force the narrow part of the paper clip through the hole punched in the plastic loop, and bend out the larger loop of the paper clip.
![[IMAGE]](LoopB.gif)
8. This metric Beam will need balancing, after it is placed in the support stand, where the original Beam was located ! The first step (1) Move the plastic sliders with the paper clips EQUAL DISTANCE FROM THE CENTER , (2) Cut a plastic strip of about 5 inches long and about 3/4 of an inch wide. (3) Gently fold it down the middle, (4) Slide it into the end of the Beam that goes up, (5) Have at least half of the plastic strip sticking inside of the beam, and start cutting off a half of a inch at a time, when it is nearly balanced, try sliding the remainder of the strip and out until it is finally balanced. Use your judgement, about how much plastic strip to use, if your Beam is really off, because of poor construction, you may have to double the plastic strip !
![[IMAGE]](Equald.gif)
9. Obtain several fishing weights, say one ounce, two ounce, three ounce and four ounce. Now, if you don't live in an area where fishing is done, you might have to resort to socket wrenches, and large nuts and bolts. For an example 3/8 inch size, 1/2 inch size and so on. Use your imagination. If you are using sockets, you may have to put thread loops in them so that they will more easily fit on the paper clip.
10. I will make reference to the lead weights, (CAUTION ** LEAD IS TOXIC TO YOUR HEALTH, SO BE SURE TO WASH YOUR HANDS WITH SOAP AND WATER AFTER HANDLING THE LEAD WEIGHTS!!
NOTE OF CHANGE:
Obtain small plastic sandwich bags, punch holes in them ( as described in the 'Spring ( Rubber band ) balance' which means that you have to use paper between layers of plastic, to be effective with the paper hole punch. Place 10 pennies of 1990 or newer date, in to the plastic small bag. This will be your standard weight of 25 grams, ( assuming that you have checked them out using the 'One gram poise' and the SBB. Place your 1 once lead weight into a plastic small bag and attache it to the other side, be sure to number all objects with a fine point magic marker. Objects that you will be using, say your lead weights, if there are more then one, each may be a different weight. Start out by moving your unknown to about 5 cm from the center, then try sliding your known, until the objects are in balance. Read the numbers under the plastic, and record them in the table. Don't forget that your zero position starts at the pivot point!
OBSERVATION :
| RESISTANCE | RESISTANCE DISTANCE | EFFORT | EFFORT DISTANCE | |
| 1. One ounce weight | ||||
| 2. Two ounce weight | ||||
| 3. Three ounce weight | ||||
| 4. Four ounce weight |
1. Repeat the above procedure, for each unknown weight, and then using the formula :
R x Rd = E x Ed
Solve for R
R = E x Ed / Rd
Now, the actual weight of a one ounce weight is equal to 28 grams, however for many reasons you will seldom come close to this answer. Try to combine a one ounce weight and a two ounce weight and compare it to the three ounce weight, and which one weighs more ? Try the same for the four ounce weight, by comparing it to the combination of the three ounce and one ounce weight. If you have two samples of the same weight compare them to each other. Why do you think that there is this discrepancy between your answer and the weight stamped on the lead weight ?
QUESTIONS:
1. The lever has two section to it, when the counter clock wise torque equals the clock wise torque the system is balanced. State the Law of the of the lever.
2. Usually the heavier object should be closer or farther from the fulcrum ?
3. Now, if you had a three straws and small box of paper clips, a straight pin, a spool of thread, a metric ruler, a fine point magic marker, two bricks, a pair of scissors, and you could use one paper clip ( known weight of 0.6 grams ) for your standard weight. Do you think that you could build a mini balance, that would be capable of weighing letters ? To see if they were under the legal limit of 1 ounces for first class mail ? Knowing that one ounce weighs 28 grams. Describe how you would go about it.
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