A balance is a basic instrument used to measure the mass of an object, using a standard weight to compare its mass and estimate the value of the mass of the unknown object. In this article, we will look at how to make a homemade scale in very few steps, so that we can use it for household measurements or present it as a science project for primary school students.
- Two disposable bottles of the same size.
- A disposable bottle larger than the previous bottles.
- An indelible marker.
- A standard weight such as a kilo of sugar or rice and objects of unknown weight.
Setting up our home scale
The first step is to cut the top of one of the two identical bottles with the help of a blade. Then, on the second bottle we are going to make the same cut with the help of the blade so that both bottles are identical.
Once this procedure is done, we are going to introduce one of these bottles into the other, so that they are like a kind of bottle with two bottoms. This system will be our plunger and the working motor of our balance.
In the next step, we are going to take the largest bottle and cut off the top in a similar way to the first bottles and we are going to fix a graduation of several centimetres on the outside, which we will do with a marker and the help of a ruler.
Next, we put 6 cm of water into the bottle and take the measurement of the graduated system. Then, we place the plunger previously created inside the bottle with water, once this is done, we take the second measurement of the water level. This measurement will be our tare or zero.
Now, to calibrate our balance, we place a known weight on the upper part and we mark up to where the water level reaches, this will be a reference value that we can vary until we create our own scale and we will be ready to measure unknown weights.
How it works
The operation of this balance is based on the properties of fluids, specifically, the pressure exerted on a fluid, since when pressure is exerted on it, the column of liquid rises above its container until the force is equalised, a principle similar to that used in manometers.