# How to Make a Scale/ Steelyard

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## Introduction: How to Make a Scale/ Steelyard

It can be use to find the weight or mass of a small object. It uses torque and a lil math, but it is very simple and cheaper to buy/build then those digital ones.

### Teacher Notes

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## Step 1: Materials

--> I used a piece of stick that was 1.6cm wide, 3.6cm tall and 47cm long. the lengths do not have to be exactly those sizes. but the height of it has to be a little taller then the ruler. (brown brick on picture)
--> I used a 99 cent 30cm wood ruler (it has cm and inches) (yellow brick on picture)
--> 1 metal Clothes Hanger (red hooks on picture)
-->a hand full of pennies (peach circles in the pink rectangle)
-->some thing to make holes on wood (holes are the black fat dots)
--> i use wood glue but you can use [Elmer's white glue]
--> 1 shoe string (shown at a letter time)
--> any piece of long tube were pennies can be stack tall (pink rectangle)

## Step 2: The Body

--> get the ruler and glue it to the end of the stick of wood (make sure the end of the wooden stick is on the same side as the ruler's 30cm indicator) (also make sure the numbers in the ruler are facing up and are not the part that is clue onto the wooden stick)
--> then it should be about 1/4 of the wooden stick left un-touched by the ruler. that un-touched part you mark (starting from the ruler's zero) every centimeter (the black lines in the brown side of the wooden stick)
--> then on the un-touched part of the wooden stick, draw a straight line all through the middle of the un-touched wooden stick
--> count 5 lines and drill a hole on the center of those lines (the center of the crosses between the two lines)
-->make sure to at least place two important holes. one under the zero on the center of the wood as shown on the bottom (this will be from where you balance your whole machine) and the second hole 5cm away from the original hole under the zero

## Step 3: Making the Part Where You Hang From / the Balance Point

-->i first cut the coil part on top of the metal clothes hanger.
-->then i straighten the cloth hanger
--> i cut a piece of it that was 17cm long
-->then i put the 17cm wire through the hole under the zero
-->I bended both edges 2cm to make two hooks facing up
-->then i bended the wire up 5cm on each side( the center that is inside the hole is 3cm)
--> now the wire should look like the red wire in the picture
--> now the tricky part comes in
--> push the two ended hooks close to each other so that they are facing each other (hooks are facing to the inside
--> push the hooks close to each the same way a paper clip is
-->the hooks are now perfectly in line to one another so that you can put a hoop (like key ring) in between the hooks (like when you put a paper clip on paper) and then after the hoop is in the two hooks, you turn the hoop so that it is perpendicular to both hooks and fits perfectly in both hooks
--> now you can hang the stick on a strong stick where the key ring fits
-->the whole stick will fall toward the side of the ruller

## Step 4: Fixing Straight Up the Body

--> now you get your tube and clue or tape it to the other end where the ruler doesn't touch the wooden stick (pink rectangle on the picture)
-->make sure the tube is sticking up and the top is open
--> now grave your pennies
--> one at a time, fill in the tube with pennies until the whole stick is balance completely (you'll have to put pennies and take away pennies until you have it complete balance) (the peach circle on the pink rectangle are the pennies)
-->after you are this, you are almost done!!

## Step 5: Hooks

--> i got the straight cloth hanger and cut two equal wires that measure 23cm each
--> make a 1cm hook on one edge of on wire then do the same to the other one
--> stick on wire in the 5cm hole. once 7cm of wire is sticking out (from the hook's side), bend it straight down. then the other end, bend it straight down as well (hook 1)
-->now the other wire, try to make a rectangle big enough that the whole stick and ruler can slide right through it smoothly. and place it 5cm away from the zero on the opposite side of the other hook (hook 2)

## Step 6: Extra Step to Make Easy Loading

-->but the shoe sting in half
--> on each end make a hoop and tie it so that he hoop stays the same even if you pull it. (it should look like number 1 in the picture, but a little bit longer..) do this to each of the two strings
--> now grave one end and make it go through the other hoop as shown on picture 2
--> you will find out how once one hoop is through the other one it makes another hoop that is much bigger (the new hoop is the square where i place the two)
--> now with the big hoop, you can place what you want to weight in there and then pull the string tight so that the big hoop will close on the object and secure it in place.
--> now you grave something in your house that you know how much it weights. for example i grave a new un-open bottle of hair gel (because on the label it told me the weight /mass of it in grams) and i attach it to the string

## Step 7: Using the Mechine

-->now you that you have something that you know how much it weights on one string (for me is the bottle of gel), you hang your known weight on the side the pennies are (known weight is the green bottle in the picture)
--> then you grave the other object you want to know how much it weights and place it on the other free hook that is on the side of the ruler (if the object is heavier then the "object you know how much it weights", move the object you don't know its weight somewhere less then 5cm; if the object weights as much as the "object you know how much it weights", place it on the 5cm mark, if the object weights more then you place it in the numbers higher then 5cm)
-->you'll be playing with it until it becomes PERFECTLY balance

## Step 8: Now Labeling It and Doing the Math

-->using physics and a few physics equations, i did the math and made a equation where all you do is place the numbers and bam!!!, you get your answer
--> i use the physics equations of torque=Fd, i also use W=mg
--> what that, i have this new equation that you can use to find how much something is
--> W= (Md) / x
--> all of those letters i label on the picture, they are the letters in gray
--> W is what you are trying to find out how much it weights
-->m is the weight of the object you know how much it weights
--> d is the distance from M to zero, which you know cause it is on the hole that marks 5cm
--> x is the finale place where w can stand and keep everything in balance (which the ruler tells you the distance for
--> this equation only tells you the mass of the object, so if you want the weight, just multiply the mass with 9.8 (which is the gravitational acceleration on the object [weight equals mass times gravitational acceleration or W=mg})]

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