Unified State Examination in Physics, 2009,
demo version
Part A
A1. The figure shows a graph of the dependence of the projection of the body's velocity on time. The graph of the dependence of the projection of the acceleration of the body on time in the time interval from 12 to 16 s coincides with the graph
| 1) |
 |
| 2) |
 |
| 3) |
 |
| 4) |
 |
Decision. It can be seen from the graph that in the time interval from 12 to 16 s, the velocity changed uniformly from –10 m/s to 0 m/s. The acceleration was constant and equal
The acceleration graph is shown in the fourth figure.
Correct answer: 4.
A2. Bar magnet mass m brought to a massive steel plate with a mass M. Compare the force of the magnet on the plate with the force of the plate on the magnet.
| 1) | |
| 2) | |
| 3) | |
| 4) |
Decision. According to Newton's third law, the force with which the magnet acts on the plate is equal to the force with which the plate acts on the magnet.
Correct answer: 1.
A3. When moving along a horizontal surface, a sliding friction force of 10 N acts on a body with a mass of 40 kg. What will be the sliding friction force after a decrease in body weight by 5 times if the friction coefficient does not change?
| 1) | 1 N |
| 2) | 2 N |
| 3) | 4 N |
| 4) | 8 N |
Decision. With a decrease in body weight by 5 times, body weight will also decrease by 5 times. This means that the sliding friction force will decrease by 5 times and will be 2 N.
Correct answer: 2.
A4. A car and a truck are moving at speeds 
and . Car weight m= 1000 kg. What is the mass of the truck if the ratio of the momentum of the truck to the momentum of the car is 1.5?
| 1) | 3000 kg |
| 2) | 4500 kg |
| 3) | 1500 kg |
| 4) | 1000 kg |
Decision. The momentum of the car is . The momentum of the truck is 1.5 times greater. The mass of the truck is .
Correct answer: 1.
A5. Sledge weight m pulled uphill at a constant speed. When the sled rises to the top h from the initial position, their total mechanical energy
Decision. Since the sled is pulled at a constant speed, its kinetic energy does not change. The change in the total mechanical energy of the sledge is equal to the change in their potential energy. The total mechanical energy will increase by mgh.
Correct answer: 2.
| 1) | 1 |
| 2) | 2 |
| 3) | |
| 4) | 4 |
Decision. The ratio of wavelengths is inversely proportional to the ratio of frequencies: .
Correct answer: 4.
A7. The photograph shows a setup for studying uniformly accelerated sliding of a carriage (1) weighing 0.1 kg along an inclined plane set at an angle of 30° to the horizon.
When the movement starts, the upper sensor (A) turns on the stopwatch (2), and when the carriage passes the lower sensor (B), the stopwatch turns off. The numbers on the ruler indicate the length in centimeters. What expression describes the dependence of the carriage speed on time? (All quantities are in SI units.)
| 1) | |
| 2) | |
| 3) | |
| 4) |
Decision. It can be seen from the figure that during t= 0.4 s caret traveled path s= 0.1 m. Since the initial speed of the carriage is zero, we can determine its acceleration:
.
Thus, the speed of the carriage depends on time according to the law .
Correct answer: 1.
A8. With a decrease in the absolute temperature of a monatomic ideal gas by 1.5 times, the average kinetic energy of the thermal motion of its molecules
Decision. The average kinetic energy of the thermal motion of ideal gas molecules is directly proportional to the absolute temperature. With a decrease in absolute temperature by 1.5 times, the average kinetic energy will also decrease by 1.5 times.
Correct answer: 2.
A9. The hot liquid was slowly cooling in the glass. The table shows the results of measurements of its temperature over time.
In the beaker, 7 min after the start of measurements, there was a substance
Decision. It can be seen from the table that between the sixth and tenth minutes the temperature in the beaker remained constant. This means that at this time the crystallization (solidification) of the liquid took place; the substance in the glass was both in liquid and solid states.
Correct answer: 3.
A10. What work is done by the gas during the transition from state 1 to state 3 (see figure)?
| 1) | 10 kJ |
| 2) | 20 kJ |
| 3) | 30 kJ |
| 4) | 40 kJ |
Decision. Process 1–2 is isobaric: the gas pressure is equal, the volume increases by , while the gas does work. Process 2–3 is isochoric: the gas does no work. As a result, during the transition from state 1 to state 3, the gas does work of 10 kJ.
Correct answer: 1.
A11. In a heat engine, the temperature of the heater is 600 K, the temperature of the refrigerator is 200 K lower than that of the heater. The maximum possible efficiency of the machine is
| 1) | |
| 2) | |
| 3) | |
| 4) |
Decision. The maximum possible efficiency of a heat engine is equal to the efficiency of a Carnot engine:
.
Correct answer: 4.
A12. A container contains a constant amount of ideal gas. How will the temperature of the gas change if it passes from state 1 to state 2 (see figure)?
| 1) | |
| 2) | |
| 3) | |
| 4) |
Decision. According to the equation of state for an ideal gas at a constant amount of gas
Correct answer: 1.
A13. The distance between two point electric charges was reduced by 3 times, and one of the charges was increased by 3 times. Forces of interaction between them
Decision. With a decrease in the distance between two point electric charges by 3 times, the force of interaction between them increases by 9 times. An increase in one of the charges by 3 times leads to the same increase in force. As a result, the strength of their interaction became 27 times greater.
Correct answer: 4.
A14. What will be the resistance of the circuit section (see figure) if the key K is closed? (Each of the resistors has a resistance R.)
| 1) | R |
| 2) | 2R |
| 3) | 3R |
| 4) | 0 |
Decision. After closing the key, the terminals will be shorted, the resistance of this section of the circuit will become zero.
Correct answer: 4.
A15. The figure shows a coil of wire through which an electric current flows in the direction indicated by the arrow. The coil is located in a vertical plane. At the center of the coil, the current magnetic field induction vector is directed
Decision. According to the rule of the right hand: "If you grasp the solenoid (coil with current) with the palm of your right hand so that four fingers are directed along the current in the coils, then the left thumb will show the direction of the magnetic field lines inside the solenoid (coil with current)". Having mentally performed the indicated actions, we obtain that in the center of the coil the magnetic field induction vector is directed horizontally to the right.
Correct answer: 3.
A16. The figure shows a graph of harmonic current oscillations in an oscillatory circuit. If the coil in this circuit is replaced by another coil, the inductance of which is 4 times less, then the oscillation period will become equal to
| 1) | 1 µs |
| 2) | 2 µs |
| 3) | 4 µs |
| 4) | 8 µs |
Decision. It can be seen from the graph that the period of current oscillations in the oscillatory circuit is 4 μs. When the inductance of the coil is reduced by 4 times, the period will decrease by 2 times. After replacing the coil, it will become equal to 2 μs.
Correct answer: 2.
A17. Light source S reflected in a flat mirror ab. The image S of this source in the mirror is shown in the figure.
Decision. The image of an object obtained with a flat mirror is located symmetrically to the object with respect to the plane of the mirror. The image of the source S in the mirror is shown in Figure 3.
Correct answer: 3.
A18. In a certain spectral range, the angle of refraction of rays at the air-glass boundary decreases with increasing radiation frequency. The course of rays for the three primary colors when white light falls from the air onto the interface is shown in the figure. Numbers correspond to colors
Decision. Due to the dispersion of light, when passing from air to glass, the beam deviates more from its original direction, the shorter its wavelength. Blue has the shortest wavelength, red has the longest. The blue beam will deviate the most (1 - blue), the red beam will deviate the weakest (3 - red), leaving 2 - green.
Correct answer: 4.
A19. There is a fuse at the entrance to the electrical circuit of the apartment that opens the circuit at a current of 10 A. The voltage supplied to the circuit is 110 V. What is the maximum number of electric kettles, each with a power of 400 W, that can be turned on simultaneously in the apartment?
| 1) | 2,7 |
| 2) | 2 |
| 3) | 3 |
| 4) | 2,8 |
Decision. An electric current with a power of 400 W passes through each kettle: 110 V 3.64 A. When two kettles are turned on, the total current strength (2 3.64 A \u003d 7.28 A) will be less than 10 A, and when three kettles are turned on, it will be more 10 A (3 3.64 A = 10.92 A). No more than two kettles can be turned on at the same time.
Correct answer: 2.
A20. The figure shows diagrams of four atoms, corresponding to Rutherford's model of the atom. Black dots represent electrons. Atom corresponds to the scheme
| 1) |
 |
| 2) | |
| 3) |
 |
| 4) |
 |
Decision. The number of electrons in a neutral atom coincides with the number of protons, which is written at the bottom before the name of the element. There are 4 electrons in an atom.
Correct answer: 1.
A21. The half-life of the nuclei of radium atoms is 1620 years. This means that in a sample containing a large number of radium atoms,
Decision. It is true that half of the original radium nuclei decay in 1620 years.
Correct answer: 3.
A22. Radioactive lead, having experienced one α-decay and two β-decays, turned into an isotope
Decision. During α-decay, the mass of the nucleus decreases by 4 amu. e. m., and during β-decay, the mass does not change. After one α-decay and two β-decays, the mass of the nucleus will decrease by 4 AU. eat.
During α-decay, the charge of the nucleus decreases by 2 elementary charges, and during β-decay, the charge increases by 1 elementary charge. After one α-decay and two β-decays, the charge of the nucleus will not change.
As a result, it will turn into an isotope of lead.
Correct answer: 3.
A23. The photoelectric effect is observed by illuminating the metal surface with light of a fixed frequency. In this case, the retarding potential difference is equal to U. After changing the frequency of light, the retarding potential difference increased by Δ U= 1.2 V. How much has the frequency of the incident light changed?
| 1) |
 |
| 2) | |
| 3) | |
| 4) |
Decision. Let's write the Einstein equation for the photoelectric effect for the initial frequency of light and for the changed frequency . Subtracting the first equality from the second equality, we obtain the relation:
Correct answer: 2.
A24. The conductors are made from the same material. Which pair of conductors should be chosen in order to experimentally discover the dependence of the resistance of the wire on its diameter?
| 1) |
 |
| 2) |
 |
| 3) |
 |
| 4) |
 |
Decision. In order to experimentally detect the dependence of the resistance of a wire on its diameter, you need to take a pair of conductors that differ only thick. The length of the conductors must be the same. You need to take the third pair of conductors.
Correct answer: 3.
A25. The dependence of the voltage on the plates of an air capacitor on the charge of this capacitor was studied. The measurement results are presented in the table.
Measurement errors q and U were 0.05 μC and 0.25 kV, respectively. The capacitance of the capacitor is approximately
| 1) | 250 pF |
| 2) | 10 nF |
| 3) | 100 pF |
| 4) | 750uF |
Decision. We calculate for each measurement the value of the capacitance of the capacitor () and average the resulting values.
| q, μC | 0 | 0,1 | 0,2 | 0,3 | 0,4 | 0,5 | |
| U, kV | 0 | 0,5 | 1,5 | 3,0 | 3,5 | 3,5 | |
| With, pF | - | 200 | 133 | 100 | 114 | 142 | 140 |
The calculated capacitance value is closest to the third answer option.
Correct answer: 3.
Part B
IN 1. Load of mass m, suspended on a spring, performs harmonic oscillations with a period T and amplitude. What will happen to the maximum potential energy of the spring, the period and frequency of oscillations, if the mass of the load is reduced at a constant amplitude?
For each position of the first column, select the corresponding position of the second and write down the selected numbers in the table under the corresponding letters.
| BUT | B | AT |
Transfer the resulting sequence of numbers to the answer sheet (without spaces).
Decision. The period of oscillation is related to the mass of the load and the stiffness of the spring. k ratio
With a decrease in mass, the oscillation period will decrease (A - 2). The frequency is inversely proportional to the period, which means that the frequency will increase (B - 1). The maximum potential energy of the spring is equal to, with a constant amplitude of oscillations, it will not change (B - 3).
Answer: 213.
IN 2. Using the first law of thermodynamics, establish a correspondence between the features of the isoprocess described in the first column in an ideal gas and its name.
| BUT | B |
Transfer the resulting sequence of numbers to the answer sheet (without spaces or any symbols).
Decision. The internal energy of an ideal gas remains unchanged at a constant gas temperature, that is, in an isothermal process (A - 1). Heat exchange with the surrounding bodies is absent in the adiabatic process (B - 4).
IN 3. A flying projectile breaks into two fragments. With respect to the direction of movement of the projectile, the first fragment flies at an angle of 90° at a speed of 50 m/s, and the second at an angle of 30° at a speed of 100 m/s. Find the ratio of the mass of the first fragment to the mass of the second fragment.
R solution. Let's depict the directions of movement of the projectile and two fragments (see figure). Let us write down the law of conservation of the momentum projection on the axis perpendicular to the direction of the projectile motion:
AT 4. In a heat-insulated vessel with a large amount of ice at a temperature, pour m= 1 kg of water with temperature . What is the mass of ice Δ m melts when thermal equilibrium is established in the vessel? Express your answer in grams.
Decision. When cooled, the water will give off the amount of heat. This heat will melt the ice mass
Answer: 560.
AT 5. An object 6 cm high is located on the main optical axis of a thin converging lens at a distance of 30 cm from its optical center. The optical power of the lens is 5 diopters. Find the height of the object image. Express your answer in centimeters (cm).
Decision. Denote the height of the object h\u003d 6 cm, distance from the lens to the object, the optical power of the lens D= 5 diopters. Using the formula for a thin lens, we determine the position of the object image:
.
The increase will be
.
The height of the image is
Part C
C1. A man wearing glasses entered the warm room from the street and found that his glasses were fogged up. What should be the outside temperature for this phenomenon to occur? The temperature in the room is 22°C and the relative humidity is 50%. Explain how you got the answer.
(Use the table for saturated vapor pressure of water when answering this question.)
Saturated vapor pressure of water at different temperatures
Decision. From the table we find that the saturated vapor pressure in the room is 2.64 kPa. Since the relative humidity of the air is 50%, the partial pressure of water vapor in the room is 2.164 kPa50% = 1.32 kPa.
The first moment a person enters from the street, his glasses are at street temperature. The room air, in contact with the glasses, is cooled. It can be seen from the table that if the room air is cooled to 11 °C or lower, when the partial pressure of the water vapor becomes greater than the saturated vapor pressure, the water vapor will condense - the glasses will fog up. The temperature outside should be no higher than 11 °C.
Answer: not higher than 11 °C.
C2. A small puck after impact slides up the inclined plane from the point BUT(see picture). At the point AT the inclined plane passes without a break into the outer surface of a horizontal pipe with a radius R. If at the point BUT the speed of the puck exceeds , then at the point AT the puck comes off the support. Inclined plane length AB = L= 1 m, angle α = 30°. The coefficient of friction between the inclined plane and the washer μ = 0.2. Find the outer radius of the pipe R.
Decision. Find the speed of the puck at the point B using the law of conservation of energy. The change in the total mechanical energy of the washer is equal to the work of the friction force:
The separation condition is the equality of the reaction force of the support to zero. Centripetal acceleration is caused only by the force of gravity, while for the minimum initial speed for which the washer is lifted off, the radius of curvature of the trajectory at the point B equals R(for higher speeds, the radius will be larger):
Answer: 0.3 m.
C3. A balloon whose shell has mass M= 145 kg and volume, filled with hot air at normal atmospheric pressure and ambient temperature. What is the minimum temperature t must have air inside the shell for the balloon to start rising? The shell of the ball is inextensible and has a small hole at the bottom.
Decision. The ball will begin to rise when the force of Archimedes exceeds the force of gravity. The strength of Archimedes is . The density of the outside air is
where p- normal atmospheric pressure, μ - molar mass of air, R- gas constant, - outdoor air temperature.
The mass of the ball is the sum of the mass of the shell and the mass of air inside the shell. The force of gravity is
where T- air temperature inside the shell.
Solving the inequality , we find the minimum temperature T:
The minimum air temperature inside the enclosure shall be 539 K or 266 °C.
Answer: 266°C.
C4. A thin aluminum bar of rectangular cross section, having a length L= 0.5 m, slides from rest on a smooth inclined plane of dielectric in a vertical magnetic field with induction B= 0.1 T (see figure). The plane is inclined to the horizon at an angle α = 30°. The longitudinal axis of the bar during movement maintains a horizontal direction. Find the value of the induction emf at the ends of the bar at the moment when the bar passes the distance along the inclined plane l= 1.6 m.
Decision. Let's find the speed of the bar in the lower position, using the law of conservation of energy:
Aluminum is a conductor, so an EMF of induction will occur in the bar. The induced emf at the ends of the bar will be equal to
Answer: 0.17 V.
C5. In the electrical circuit shown in the figure, the current source emf is 12 V, the capacitance is 2 mF, the coil inductance is 5 mH, the lamp resistance is 5 ohms, and the resistance of the resistor is 3 ohms. At the initial moment of time, the key K is closed. What energy will be released in the lamp after opening the key? Ignore the internal resistance of the current source, as well as the resistance of the coil and wires.
Decision. Let's introduce the notation: ε - EMF of the current source, C- capacitance of the capacitor, L- coil inductance, r- lamp resistance, R is the resistance of the resistor.
While the key is closed through the capacitor and the lamp, no current flows, but current flows through the resistor and coil
The energy of the system capacitor - lamp - coil - resistor is equal to
.
After opening the key, transient processes will occur in the system until the capacitor is discharged and the current becomes zero. All energy will be released as heat in the lamp and resistor. At each moment of time, the amount of heat is released in the lamp, and in the resistor -. Since the same current will flow through the lamp and the resistor, the ratio of heat released will be in proportion to the resistances. Thus, energy is released in the lamp
Answer: 0.115 J.
C6.-meson mass decays into two γ-quanta. Find the momentum modulus of one of the resulting γ-quanta in the reference frame where the primary -meson is at rest.
Decision. In the reference frame where the primary -meson is at rest, its momentum is zero, and the energy is equal to the rest energy. According to the law of conservation of momentum, γ-quanta will scatter in opposite directions with the same momentum. This means that the energies of γ-quanta are the same and, therefore, equal to half the energy of the -meson: . Then the momentum of the γ-quantum is equal to
Part 1
A1. The figure shows a graph of the dependence of the projection of the body's velocity on time.
The projection of the acceleration of the body in the time interval from 12 to 16 s is represented by the graph:
A2. Bar magnet mass m brought to a massive steel plate with a mass M. Compare the force of the magnet on the stove F 1 with plate action force on magnet F 2 .
1) F 1 = F 2 ; 2) F 1 > F 2 ; 3) F 1 < F 2 ; 4) F 1 / F 2 = m/M.
A3. When moving along a horizontal surface, a sliding friction force of 10 N acts on a body with a mass of 40 kg. What will be the sliding friction force after a decrease in body weight by 5 times if the friction coefficient does not change?
1) 1 N; 2) 2 N; 3) 4 N; 4) 8 N.
A4. A car and a truck are moving at speeds υ 1 = 108 km/h and υ 2 = 54 km/h. Car weight m= 1000 kg. What is the mass of the truck if the ratio of the momentum of the truck to the momentum of the car is 1.5?
1) 3000 kg; 2) 4500 kg; 3) 1500 kg; 4) 1000 kg.
A5. Sledge weight m pulled uphill at a constant speed. When the sled rises to the top h from the initial position, their total mechanical energy is:
1) will not change;
2) increase by mgh;
3) will be unknown, because the slope of the hill is not set;
4) will be unknown, because the coefficient of friction is not set.
1) 1; 2) 2; 3) 1/4; 4) 4.
According to the FIPI website http://www.fipi.ru. Instructions for completing the work of the Unified State Exam-2009, the criteria for evaluating solutions to problems of part 3 for 1 and 2 points, the conditions for recording the solution of tasks, as well as another option, see No. 3/09. - Ed.
When water does not flow well from the mixer, you can deal with the problem only by knowing what caused the poor pressure. Weak pressure makes it impossible to fully use the shower or bath. Problems with water significantly reduce the comfort of living, so it is impossible to fully enjoy the benefits of civilization.
Causes affecting the water pressure in the faucet
To eliminate a malfunction that leads to a violation of the pressure or its complete absence, you need to understand why the water from the tap does not flow well.
Most often, the problem lies in the following circumstances:
- Faucet blockage. A decrease in pressure and a decrease in the water jet occurs due to clogging of the aerator, which is an insert and filters water. Confirmation of this breakdown theory is such a violation as a decrease in pressure in only one mixer, when other taps in the house are working normally.
- The formation of cork from rust, particles of silt and scale in the pipe. A gradual decrease in pressure in this situation can lead to a complete blockage of the throughput diameter of the connecting filter or the pipeline fitting itself.
- Reducing the pressure of the water supply in the water main. The problem may be at the level of the pumping station. It is also possible to depressurize the pipeline.
- Incorrect calculations when designing a water main. For example, during the laying, pipes of a larger diameter were used than the one that was used on neighboring branches; a large length of water pipes, which does not correspond to the capabilities of pressure equipment.
The drop in pressure of both hot and cold water can be caused by factors such as the simultaneous consumption of liquid in large quantities. As a rule, under such circumstances, the water does not flow well in the evening, when the bulk of the inhabitants of the area return home.
Solving pressure problems
If the pressure drops or the water does not flow at all, you can try to find out the cause of the malfunction yourself, and then fix it. It is worth noting that not all breakdowns can be repaired by yourself. In case of accidents at the station, depressurization of the pipeline and similar reasons, the relevant competent services are involved in the repair.
You can try to clean the clogged section of the pipe from the riser to the valve with a special cable. When the water does not flow well from the neighbors below and above, it can be argued that the riser is clogged. It is almost impossible to clean it. It is to be replaced.
All repairs are carried out after the water is shut off.
If the faucet itself is clogged, the mixer can be cleaned. This will require a wrench. With it, you need to unscrew the aerator. Due to the fact that the aerator has small nozzles, it clogs quickly. To clean the aerator, you need to substitute it under running water and rinse it. When the problem is not in the aerator, you will need to dismantle the valve and unscrew the lock washer that holds the locking element in the housing seat, and get to the axle box and remove it. Next, the body is cleaned of scale, plaque, etc. When everything is finished, you will need to assemble everything in the reverse order.
If the problem appeared in the shower and after cleaning the faucet there is still no hot water, you will need to clean the sprayer. It is dismantled using an adjustable wrench, after which it is placed in a saucepan and filled with water, and then placed on the stove. Add vinegar or citric acid to the water. You don't need to boil. An acidic environment is detrimental to plaque and other deposits that have formed on the sprayer. After cleaning, the sprayer must be rinsed under running water and reinstalled.
If the problem is not in the mixer, but in the water pipes, then it is better to contact a specialist (locksmith, plumber).
In order to fix the problem of poor water pressure yourself, you will need:
- shut off the water;
- dismantle the plug of the coarse filter;
- remove and rinse the wire cassette.
The filter element is returned to its place and the plug is screwed using a special tape for sealing. If the cause was not a clogged coarse filter, it can be assumed that the failure of the fine cleaning system was to blame.
After disconnecting from the water supply, it is necessary to check the pressure in the free pipe. To do this, open the central valve. If everything is normal, the liner is replaced and the filter glass is washed from the accumulated dirt, and then everything is mounted in its original place.
When none of the above helps, you can try flushing the pipes under pressure. To do this, turn off the water with a valve located near the filter, unscrew the flexible hoses or the mixer, if it is wall-mounted.
Water will flow from the pipes, which must be sent to the sewer or a pre-prepared container (basin, bucket). Pipe cleaning is recommended to be done with an assistant. It will take sharply for 1-2 seconds to open and close the valve.
Weak pressure in the faucet can piss off even the most balanced homeowner. After all, the duration of filling the kettle or coffee maker, and the performance of the washing machine or dishwasher depend on the pressure.
In addition, with poor pressure, it is almost impossible to use either the toilet or the shower or bath. In a word, if there is no pressure in the tap, then the house will not have the comfort of living.
We understand the causes of low water pressure in the tap
What weakens the pressure of water in the faucet?
Why a weak water pressure in a tap can ruin even the happiest life, even in the most perfect house or apartment, we have already discussed with you. However, moaning will not help grief. Moreover, this problem is not as terrible as it seems. One has only to understand what has weakened the pressure, and you will get an almost ready-made recipe for eliminating this trouble.
At the same time, the list of TOP 3 reasons for the drop in pressure of hot or cold water is as follows:
- Clogged faucet . In this case, the intensity of the water jet is weakened by a cork made of rust and scale, which clogged the aerator, filter insert (mesh) or bushing. Moreover, only one tap in the house suffers from this problem. That is, if your tap water is not flowing well, for example, in the kitchen, but there are no problems in the bathroom, then you will have to disassemble and clean the problematic point of consumption.
- . In this case, the same particles of silt, rust or scale are to blame. Only now they block not the faucet aerator or the faucet mesh, but the filter built into the water supply. In the worst case, such deposits can block the flow diameter of the connecting fitting or the pipe fitting itself.
- . In this case, the cause of the weakening may be either a failure at the level of the pumping station, or a depressurization of the pipeline. Failure at the station can only be corrected by repair crews of utilities. The indicator of this breakdown is the lack of water in the entire microdistrict. Loss of tightness is diagnosed visually - by a stream of water spouting from the body of plumbing fittings. Any locksmith from a service company can fix this breakdown.
- In addition, speaking about the reasons for the weakening of pressure, it is necessary to mention possible miscalculations in the arrangement of a specific water supply line . Incorrect diameter (larger than the previous branch), excessive length (not matching the characteristics of the pressure equipment) - these are the main reasons for the pressure drop in the new water supply network.
|
|
If you don’t want to deal with them, order a water supply project from professionals.
Well, now that you already know the reasons for the drop in pressure in the tap, it's time to figure out how to eliminate this defect in the water supply.
What to do if cold and hot water from the tap does not flow well?
It all depends on the cause of the pressure drop.
For example, if your faucet is clogged, you will need to do the following:
Removing the faucet aerator for cleaning
- Take an adjustable wrench and twist it off the "spout" of the crane - Foaming jet of water nozzle. This part has very small nozzles. Therefore, aerators are clogged with a frequency of once every six months. And if we are talking about a mixer tap with hot / cold water, then the frequency of cleaning the nozzles is reduced to 2-3 months. The dismantled aerator is washed under running water.
- If the aerator is clean and the water is weak, you will have to dive even deeper into the faucet design. . Indeed, in this case, you need to get close to the locking unit - the box. To do this, dismantle the valve (faucet handle) and unscrew the lock washer holding the locking element in the body seat. Next, you remove the shut-off assembly from the housing and clean off silt or scale deposits from its surface. In the final, you will have to assemble the crane, acting in reverse.
Before dismantling the shut-off valve assembly, be sure to turn off the water supply by closing the water valve closest to the point of consumption. Otherwise, you will flood the entire apartment.
- If the source of the problem is not the faucet, but the “sprayer” in the shower or bathroom, you will have to proceed a little differently. First shut off the supply to the atomizer. Then remove it from the rack or metal hose using an adjustable wrench. Immerse the removed part of the atomizer in a saucepan of vinegar. Heat up this medium on a hot plate. Wash off the scale with water. Put the nozzle back in place.
If the smell of vinegar irritates you, try a 10% citric acid solution. To prepare it, it is enough to dissolve 100 grams of dry acid powder - it is sold in any confectionery department - in a liter of water.
If you do not have the desire to mess with the crane - call a locksmith from the management company. He will solve this problem right before your eyes.
What to do if the water pressure in the tap is poor, we hope you already understand.
Now let's move on to pipes:
- First of all, turn off the water by turning the central valve near the meter.
- Next, dismantle the plug of the coarse filter. Remove the wire cassette and wash it in a container. Then return the filter element to its place, renew the seal and screw the plug.
- After the revision of the coarse filter, proceed to check the fine filter system. First, disconnect it from the water supply and check the pressure in the free pipe by slightly opening the central valve. If everything is in order, change the liner, simultaneously washing the filter glass from particles of accumulated dirt. In the final, everything, of course, is mounted in its original place.
- If the filters are clean, and the water still does not come out of the tap with the proper force, then the cause of the drop in pressure is a blockage in the pipes themselves. Localization of this problem and its elimination is an extremely time-consuming task. Therefore, after unsuccessfully cleaning the filters, you will have to call the management company and report a problem with the patency of the pipes in the water supply.
If you did not change the wiring of the water supply system in the apartment, the management company will pay for cleaning the pipes. After all, it is she who should monitor the performance of "native" engineering communications.
