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What is the formula of buoyancy
Ha... I have f = PGV row
What formula is bil Δ t = MV q = I Δ t?
The formula of the magnetic force on the current is: F = bil, bil Δ t is the impulse of the magnetic force, MV is the momentum, bil Δ t = MV shows that the total amount of the magnetic force is equal to the change of the momentum of the object (the initial momentum is zero). This is the application of the momentum theorem
Q = I Δ t is derived from the definition of current intensity (I = q / T). The definition of current intensity is the charge flowing to the cross-sectional area of conductor in unit time
When an object is placed on a table, the left side receives a force of 10N to the right, and the right side receives a force of 2n to the left. The object remains motionless?
Is friction one or two
Gravity, support force, left pull force, right pull force and static friction force are 5
About the formula of physics electricity in junior high school, especially the electric power, I always confuse the mechanical efficiency of pulley with the mechanical efficiency of calorific value
Find the relationship between electric power and resistance, heat, current and voltage in series circuit and parallel circuit
What is the relationship between series circuit, parallel circuit, electric power, electric energy, resistance, voltage and current?
Series circuit features:
1. The current of series circuit is equal everywhere; I = I1 = I2 = in
2. The total voltage of the series circuit is equal to the sum of the voltages of the two ends of each consumer; u = U1 + U2
3. The total resistance of the series circuit is equal to the sum of the resistances of the consumers; r = R1 + R2
(n resistors with resistance value R are connected in series, and the total resistance is equal to NR)
4. The total resistance of series circuit is greater than that of any consumer
5. The total resistance increases when the series circuit is connected in series again;
6. Increasing the resistance of any electrical appliance will increase the total resistance
7. The voltage distribution is proportional to the resistance; R1 / r2 = U1 / U2
Characteristics of parallel circuit:
1. The total current of parallel circuit is equal to the sum of branch currents; I = I1 + I2
2. The voltage at both ends of each branch in parallel circuit is equal; u = U1 + U2
3. The reciprocal of the total resistance of the parallel circuit is equal to the sum of the reciprocal of the resistance of each branch; 1 / r = 1 / R1 + 1 / R2
(for two branches, r = r1r2 / (R1 + R2; the total resistance is greater than 1 / 2 of the minimum resistance and less than the minimum resistance)
(n resistors with resistance value of R are in parallel, and the total resistance is R / N)
4. The total resistance of parallel circuit is less than that of any branch
5. If the parallel circuit is connected with another resistor, the total resistance will be reduced
6. The total resistance increases with the increase of any branch resistance
7. Parallel shunt, the distribution of current and resistance is inversely proportional; R1 / r2 = I1 / I2
What is e = MC2
E is the total energy, M is the mass, C is the speed of light. That is to say, the total energy of an object is equal to the mass of the object times the square of the speed of light
If a certain pulley is changed to a movable pulley, its mechanical efficiency is calculated without friction ()
A must increase B must decrease C must remain unchanged d must change
B, right
When using the fixed pulley, it is not necessary to overcome the extra work of the pulley. When using the movable pulley, it is necessary to overcome the extra work of the pulley. Therefore, the mechanical efficiency must be reduced
Who can explain this formula for me? E = MC2
Einstein's famous mass energy equation E = MC ^ 2, e for energy, m for mass, and C for speed of light
The formula describes the relationship between energy and mass
Formula g = g in mg=______ Read as_______ His physical meaning is_______
The acceleration of gravity is 9.8n/kg. The gravity of a kilogram object is 9.8n/kg
E = MC2 unit conversion
What's the matter with the unit conversion in this formula?
The theory of mass energy equivalence is the most important inference of Einstein's special theory of relativity, that is, the famous equation: e = MC & sup2; (energy = mass ╳ the square of the speed of light), where e is energy, M is mass, and C is the speed of light; that is to say, all substances contain the energy of mass multiplied by the square of the speed of light. This can explain why the speed of an object cannot exceed the speed of light
All the energy of a static object is contained in its static mass. Once it moves, kinetic energy will be generated. Because mass and energy are equivalent, the energy in motion should be added to the mass. That is to say, the mass of a moving object will increase. When the speed of the object is far lower than the speed of light, the increased mass is very small, such as when the speed reaches 0.1 of the speed of light, For example, when the speed reaches 0.9 of the speed of light, the mass more than doubles. At this time, the object needs more energy to continue to accelerate. When the speed approaches the speed of light, the mass increases linearly with the increase of the speed. When the speed approaches the speed of light, the mass tends to be infinite and needs infinite energy, No object can move at the speed of light. Only particles with zero mass, such as photons, can move at the speed of light
In the international system of units, the unit of energy (E) is Joule (J), the unit of mass (m) is kilogram (kg), C is the propagation speed of light in vacuum, and the unit of speed is meter per second (M / s)
On the formula g = mg
Can the formula show that the mass of an object is proportional to the gravity it receives?
That's not right
G = mg means that the gravity of an object is directly proportional to its own mass, but it must not be reversed to say that "the mass is directly proportional to the gravity it receives."
The watchtower owner noticed that "the mass is proportional to the gravity he receives." this is completely wrong
RELATED INFORMATIONS
- 1. In a fixed triangle inclined plane, an object is stationary on the inclined plane, the mass of the object is m, and the elevation angle of the inclined plane is a. how to calculate the supporting force and friction force of the object? Use sin and COS to calculate
- 2. What do u, F and V represent in physical head and neck? It's the lens in physics of grade two. It's like the distance between the lens and the object
- 3. What is the meaning of "U > F" and "V > U"?
- 4. All the related formulas of gravitation in higher physics
- 5. What is correct about the power formula P = w / T and P = FV A. From P = w / T, as long as we know w and T, we can get the power at any time B. From P = FV, we can only calculate the instantaneous power at a certain time C. From P = FV, we know that the power of a car is directly proportional to its speed D. From P = FV, when the engine power is constant, the traction is inversely proportional to the speed I chose D, but B why not? If the problem is only two words, can you give me an example?
- 6. What do F and V in the formula P = FV represent?
- 7. Calculation formula of power: P = w / T = FS / T = FV What do "P", "W", "t", "F", "s", "t" and "V" refer to? What are the units?
- 8. The formula of power
- 9. What's the difference between P = FV and P = FS? I don't know which one to use most of the time
- 10. What do g and h in the pressure formula P = P (density) GH represent respectively? Under what circumstances is the formula of pressure used?
- 11. Buoyancy formula of water Who knows
- 12. Calculation formula of water buoyancy V row It is the calculation formula of V row, f floating = P liquid GV row
- 13. How to deduce the formula of buoyancy?
- 14. How is the buoyancy formula derived?
- 15. 1. The buoyancy of a small ball with a volume of 2x10 cubic meters and a volume of negative cubic meters is - Niu if it is completely immersed in water. If half of its volume is immersed in water, the buoyancy is - Niu 2. When the gravity of the metal block is 26.5n and the metal block is suspended by a spring scale and immersed in water, the indication of the spring scale is 16.7n. The buoyancy of the metal block under water is - n 3. An object weighing 4 N, with a volume of 0.5 cubic decimeter, will be completely immersed in water, and the buoyancy it receives is - cow, it will lose weight in water—— 4. If a piece of wood weighs 20n and floats on the surface of the water and is still, the buoyancy of the piece of wood to the water is - Niu 5. An ocean going ship sailed into the Huangpu River from the East China Sea. The ship realized the buoyancy it received
- 16. As shown in the figure, a piece of lead is hung under an inflated balloon with a thin thread, put it into the water, and it is just in a static state somewhere. If some water is slowly released from the bottom, the lead and the balloon () A. Still able to stand still B. move down C. move up D. stand still. It's possible to move up or down
- 17. Typical problems in junior high school physics
- 18. Xiaohua did the experiment of "estimating the value of atmospheric pressure." (1) please complete the following experimental steps. A. push the piston of the syringe to the top of the syringe barrel______ Then seal the small hole of the syringe with a rubber cap. B. fasten the neck of the piston of the syringe with a fine nylon rope so that one end of the rope is connected with the hook of the spring dynamometer, and then pull the syringe barrel horizontally and slowly to the right______ Write it down______ It is equal to the pressure of the atmosphere on the piston, F.C______ , denoted as l, read out the volume V of the syringe, then the area s of the piston=______ Finally, the value p of atmospheric pressure at this time is calculated=______ (write the expression with the measured quantity). (2) in the experiment, Xiaohua used the measuring instrument correctly, and the reading was correct, but she found that there was always deviation in the measurement results, which may be caused by (write two points)______ ．
- 19. The formula of buoyancy
- 20. The meaning and calculation formula of 1 ＼ G 2. On buoyancy formula