Why does a balance have to be used on a level table?

The balance must be placed on a horizontal plane to measure the mass of the object, because at this time, the balance is made with the two disks of the balance in horizontal balance, and the vernier scale can be used!

The situation that the landlord said is indeed possible, that is to say, even if the balance is not placed on the horizontal plane, it can be measured, but please note that the landlord can only use weights for measurement, not travel codes.

Because when the vernier ruler is horizontal, the force arm of the vernier code is the real mass reading, if the balance is not placed horizontally, when the vernier code must be used, the vernier code will be dialed to a certain position, and then the reading of the vernier code is tilted and the force arm becomes smaller, so the verge must be dialed to a larger reading, so the measurement result is wrong.

There is no absolute level at all, and there is no absolute measurement. The measurement method is called to minimize errors.

First of all, it is necessary to know that the center of gravity and the fulcrum of the scales are only close, but they do not coincide.

In the tilt condition, the center of gravity of the scale arm is offset, forming a moment at the fulcrum of the scale and increasing with the tilt (friction balance is required in the no-load state), resulting in an increase in measurement error. In addition, it is not convenient to operate.

If you use it yourself, the desktop is not horizontal.

If you're doing an experiment to show the teacher or taking an exam, you should mention that it's a horizontal desktop.

In fact, the book also says that it should be placed on a horizontal table, but the book does not say that it is not allowed on a horizontal table.

The horizontal table top makes it easy to see if the balance is more precisely balanced.

Don't you find it difficult to tell if the balance is balanced if you put it on an inclined surface? The reason is to make it easier to judge whether the balance is balanced or not.

You have one less to think about, after the level is tilted, the code will have a static friction force on the track of the code, and this static friction force will have a component force in the vertical direction, which will of course affect the measurement results.

You say"Leveled on an inclined plane and weighed? "

How to tune? Is it tuned to the level? Or parallel to the inclined plane?

If it is horizontal, then the pointer does not point to the middle of the scale, if you change the center line datum on the disk, then different inclined planes will have different middle lines, which is obviously not suitable.

If it is parallel to the inclined plane, it is obviously impossible to achieve it, how to adjust it parallel to the inclined plane? The torque of the two pallets is equal, and the direction of the force is the same, if one is high and one is low, then the low pallet will definitely be low to the bottom, and it is impossible to be parallel to the inclined plane?

Generally speaking, each kind of measuring tool has international standards, they are the crystallization of the masters' careful consideration, there will be no problem, according to this standard will make the measurement simpler, of course, some do not have to be in accordance with the standard, that depends on their own wisdom!

If the scale is crooked, how do you know if it is flat? Go test again ? That would be too much trouble.

Therefore, the truth put forward by the predecessors, don't question it casually, it has been used for so many years, if it is unreasonable, it will be abolished long ago, but the scientific spirit is commendable!

Because the dial and the base are connected together, if the tray is not placed horizontally, the tray will form an angle with the base, which will cause reading errors.

When judging whether the balance is balanced, just observe whether the pointer points to the middle scale.

The oblique scale is also slanted, and it is impossible to judge the balance.

You're right, then you can weigh it on an inclined plane.

The names of the various parts of the balance are shown below:

Extended Resources:

1. Scales

A balance, a weighing instrument. Two arms are formed by the fulcrum (axis) supporting the balance beam in the center of the beam, and a disc is hung on each arm, one of which holds an object of known mass and the other disc holds the object to be measured, and the deflection of the pointer fixed on the beam when it does not swing and points to the center scale indicates the mass of the object to be measured. A balance is a equal-arm lever.

A balance is a weighing instrument, which is an instrument that measures the mass of an object. It is made according to the principle of lever, there is a small plate at each end of the lever, one end of the weight, the other end of the object to be weighed, the lever ** is equipped with a pointer, when the two ends are balanced, the mass (weight) of both ends is equal. Modern balances are becoming more and more sophisticated, more and more sensitive, and there are more and more types.

We all know that there are ordinary balances, analytical balances, constant analytical balances, micro analytical balances, semi-micro analytical balances, and so on.

Second, the use of the balance

To be placed in a horizontal place. The game code should be reset to zero.

Adjust the balance nut (the nut at both ends of the balance) to adjust the zero point until the finger is aligned with the ** scale mark.

The left tray is placed to weigh the object, and the right tray is placed with weights (left object right yard). According to the properties of the weighed object, it should be placed on glassware or clean paper, and the mass of the glassware or paper piece should be weighed on the same balance in advance, and then the substance to be weighed should be weighed.

The added weights are gradually reduced from the maximum value of the estimated weighed object. Pallet balances can only be weighed to the gram. Add or subtract weights and move the yard on the ruler until the pointer is aligned with the tick mark again.

Objects that are too cold or too hot should not be weighed on a balance. It should be weighed (or weighed in a special vessel) after being placed in a desiccator at room temperature.

The mass of the object = weight of the weight + the number of degrees displayed by the code.

The weights must be handled gently with tweezers, and the weights should be placed in the weight box, and the yards should be moved back to the zero point after weighing.

When weighing dry solid pharmaceutical products, a sheet of paper of the same quality should be placed on each of the two trays, and then the drug should be weighed on the paper.

Drugs that are prone to deliquescent must be weighed in glassware (e.g., small beakers, surface dishes).

If the weight is rusty, the measurement result is small; If the weight is worn, the measurement result is too large.

Before using a tray balance to measure the substance of an object, the balance should be placed on a level table

And put the code at the zero scale of the ruler, and then adjust the balance on the beam, so that the finger is aimed at the zero scale of the index dial, so that the balance beam is balanced. When measuring, the object to be measured should be placed on the left plate and the weight should be placed on the right plate.

In the measurement, in order to protect the weight of the scale, Huidong should use tweezers to pick the weight; When weighing chemicals, never place them directly in the tray.

First, take out the balance and place it on the horizontal table, and move the code to the 0 tick line at the left end of the scale before use. Adjust the balance nut on the beam, so that the pointer points to the first engraved line of the index plate, then the beam balances Naguess, and the method of adjusting the balance nut can be attributed to the nut counterpointer.

When weighing, put the measured object in the left plate, estimate the mass of the measured object, put it to the corresponding size weight with tweezers, and adjust the vernier to the balance balance. The mass of the right disk weight plus the power on the vernier scale is the mass of the object being measured. After the measurement is completed, the measured object is removed, the weight is put back into the box, and the code is dialed back to the zero scale mark of the ruler.

When adjusting, place the balance on a level table and move the code to the 0 scale. Attached: Rules for the use of pallet balances (how to use):

Twenty-four words: "On the water platform, the swimming code is zero, the beam is balanced, the left thing is right, the first big and then the small, the beam is balanced." The details are as follows (five-character policy):

a) "Look": Observe the weighing of the balance.

Shouldn't it be in a physics book?

Two. Balance use.

1.Adjust the level: Before the balance is started, you should observe whether the blister in the level at the rear of the balance is located in the ring, otherwise it will be adjusted by the anchor bolt of the balance, and the left hand will rise and the right hand will fall.

2.Warm-up: A minimum of 30 minutes is required to warm up the balance when it is turned on after the initial power supply or after a long power outage. Therefore, laboratory electronic balances should not be cut off from power supply too often under normal circumstances.

3.Weighing: Press the ON OFF button to turn on the display; Wait for the instrument to self-test.

When the display shows zero, the self-test process is over and the balance can be weighed; Place the weighing paper, press the tare keys on both sides of the display screen, and when the display shows zero, add the reagent to be weighed on the weighing paper. After weighing, press the ON off button to turn off the display.

Global Weighing Instruments.

Refer to the Physics Textbook for Secondary 2

Pallet balances. Reset the code to zero. Adjust the balance nut.

Point the pointer to the very middle of the reading disc. After that, don't move the nut. Place objects on the left tray.

The weights are placed on the right. If you add the minimum weight, the pointer is still biased to the right. Then add up the total weight mass and the number of the weights to equal the mass of the object on the left.

Screw yard scale, pointer ruler with tray.

The adjusting screws are balanced, and the object code is separated from the left and right.

Take the code with tweezers, first large and then small in mind.

The drug cannot be put directly, and it must be restored after weighing.

Explanation: 1. Screw yard scale, pointer ruler has tray: these two sentences say the main components that make up the tray balance: screws, yards, scales, pointers, and trays (divided into left and right).

2. Adjust the screw to achieve balance: It means that before weighing, you should first check whether the balance is in a balanced state. If it is unbalanced, the screws should be adjusted to balance it.

3. The object code is separated from the left and right:"things"refers to the substance to be weighed; "yards"Refers to the weight of the scale. This means that the object to be weighed should be placed in the left plate and the weight should be placed in the right plate.

4. Use tweezers to pick up the code: This sentence means that when taking the weight, you must not take it by hand, but must use tweezers to pick it up.

5. First big and then small in mind: It means that when adding weights, you should first clamp the weights with large weights, and then clamp the weights with small weight (and then move the code).

6. The drug can not be placed directly: it means that the drug to be weighed cannot be placed directly on the tray (association: you can put a piece of paper of the same size on each of the two trays, and then put the weighed drug on the paper, and the wet or corrosive drug must be weighed in a surface dish or beaker).

7. Restore after weighing: It means that after weighing, the weight should be put back into the weight box, and the code should be moved back to zero, so that the balance can be restored to its original state.

1.Adjust the level: Turn the two foot screws on the balance base plate by hand until the tip of the hammer is aligned with the inverted cone on the base plate.

Some balances indicate the level without a hammer and with a level bubble. Adjust the foot screws until the bubble of the level bubble is at **, and the level is adjusted.

2.Adjust the balance of the beam: remove the object from the weighing pan and place the yard in the zero position.

Turn the knob clockwise to raise the beam and see if it balances. Because the scales are very sensitive, if you can see which side is heavier if you rise a little, you don't have to raise the beam to the highest point. Lower the beam and adjust the nuts (balance stones) at both ends of the beam until the beam is balanced.

The balance is indicated by the hands, and if the hands swing the same number of degrees around the zero scale after the beam is raised, the beam is considered to be balanced and there is no need to wait for the hands to rest.

3.Measure the mass of the object: use tweezers when picking and placing weights, not hands, and cultivate students to develop good experimental habits.

When measuring the mass of the object, place the object on the left weighing pan of the balance, place the weight on the right weighing pan of the balance, increase or decrease the weight appropriately and move the yard until the beam is balanced. At this time, the mass of the object to be measured on the left disk is equal to the sum of the mass of the weight on the right disk and the indication value of the traveling code. (Note:.)

To move objects and weights, be sure to lower the beams of the scales).

4.Reading: The mass of the measured object can be known by reading out the mass of the weight and the indication value of the code.

When the weight is quality, it is generally from large to small, take one and read one, and add it while reading. The removed weights should be placed back into the corresponding slots in the weight box. However, for students who are using the balance for the first time, it is also possible to count and add it on the weighing pan for easy review.

However, the weights should not be counted elsewhere to avoid losing them. In the experiment, the mass of the nut and then the coin was weighed.

How to use a pallet balance:

1.Start by placing the pallet balance in a level position. The code is reset to zero.

2.Adjust the nuts at both ends of the balance until the finger is aligned with the ** scale mark.

3.The left tray is placed to weigh the object, and the right tray is placed with weights. Add or subtract weights and move the yard on the ruler until the pointer is aligned again.