![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
How to judge a problem is to use kinetic energy theorem, momentum theorem, energy conservation or energy conservation. What is the ideological basis? How to correctly analyze the problem? How to correct the formula for the problem that can't be solved
When it comes to velocity, the theorem of kinetic energy is used. When it comes to the collision between two spheres and two objects, the conservation of momentum and the theorem of momentum are used. When it comes to the transformation of potential energy and kinetic energy and the resultant external force of the object (system) being analyzed is zero, the law of conservation of energy is used
The relationship between conservation of momentum and conservation of energy
For example, kinetic energy is conserved, but mechanical energy is conserved, and there is elastic potential energy. M and m have the same velocity, and the initial velocity is V1. After springing off, M's velocity is V2, M's velocity is V3, and the known elastic potential energy is EP
The formula is
(M+m)·V1=M·V2+m.V3
½(M+m)·V1=½M·V2²+½m·V3²+Ep
Ask for help, can't calculate V2 and V3 derivation formula. Seek expert solution. Calculate out, later can directly use several generations of formula, don't calculate for a long time
This formula should be (M + m) · V1 = m.v2 + m.v3 & # 189; (M + m) · V1 = # 189; m.v2 & # 178; + # 189; m.v3 & # 178; - EP, where V2 and V3 have the factor of sign in the momentum formula. V2 = [(M + m) · v1-m.v3] / m
A comparison between conservation of momentum and conservation of energy?
Not a concept, nothing to compare
RELATED INFORMATIONS
- 1. Conservation of momentum, conservation of energy A smooth inclined plane with height h and angle a is placed on a smooth horizontal plane, and a slider slides along the inclined plane to the bottom. If the velocity of the inclined plane is V2, the velocity of the slider relative to the inclined plane is V1, Simultaneous: MGH = 1 / 2m (v1sina) ^ 2 + 1 / 2mv2 ^ 2 + 1 / 2m (v1cosa-v2) ^ 2 mv1cosa=(M+m)v2
- 2. There is a formula for the conservation of momentum: how can p = √ 2mek be deduced, and under what conditions can it be used?
- 3. A ball with mass m and velocity V collides with a static B ball with mass 3M. The collision may be elastic or inelastic, so the velocity of B ball may be () A. 0.6vB. 0.4vC. 0.2vD. 0.1v
- 4. Derivation process of stiffness coefficient relationship of series spring? Series connection: stiffness coefficient relation 1 / k = 1 / K1 + 1 / K2 How to deduce? The detailed process is needed If you can, add the parallel derivation process. But the best answer is to look at the series
- 5. What is the perimeter formula of trapezoid
- 6. Area formula for all figures
- 7. Area formula of figure The more detailed it is, the more answers we have in common
- 8. Calculate the area and volume of all figures,
- 9. How to convert building area and residential area? How much is the building area converted into residential area? What is the formula?
- 10. I asked a math problem and suddenly became interested in math. The algorithm for calculating handshake is 7 * 6 / 2 = 21. Then if I only tell you how to calculate the total handshake amount, for example, the total handshake amount is 74
- 11. At the initial velocity of V0 = 10m / s, throw a small ball with mass of M = 2kg at an angle of 30 degrees with the horizontal direction, ignoring the effect of air resistance. G is taken as 10m / S ^ 2. Calculate the velocity of the small ball at the end of the second after throwing
- 12. When will high school physics consider using the kinetic energy theorem, the conservation of mechanical energy, the conservation of energy, the conservation of momentum theorem, and the conservation of momentum theorem? And the left hand rule, how to use the right hand rule? And how to use Lenz's law?
- 13. The mass m moves at the velocity V and collides with the mass M. after the collision, the momentum of the mass m is equal to that of the mass M. the mass ratio m m m may be () A. 2B. 3C. 4D. 5
- 14. An object of mass m collides with a stationary object of mass m at its initial velocity v. after the collision, the momentum of the two objects is equal. The possibility of M / M is obtained
- 15. 1. An object is thrown up 420 away from the ground and lands after 10 seconds, 2. The car with mass m moves forward on a smooth horizontal plane with speed V1. There is a man with mass m on it. He asks how fast the car is when the man jumps backward and horizontally from the speed V2 of the car, This involves the relative speed, I think people's speed should be (V1 - V2) But the answer is (v-v2). He sets V to make the speed of the car after jumping. I think the speed can't change suddenly. It should be v1. Why
- 16. The mass of the inclined trolley is m and the height is h. When an object with mass m slides down from the top of the trolley, the speed of the object sliding away from the bottom of the inclined trolley is set as V, regardless of all friction. The following statements are: ① the speed of the object sliding away from the trolley v = 2GH; ② the speed of the object sliding away from the trolley V < 2GH; ③ the speed of the object sliding away from the trolley v = MVM; ④ the speed of the object sliding away from the trolley V < MV M where the correct one is () A. Only (1) and (3) correct B. only (1) and (4) correct C. only (2) and (3) correct D. only (2) and (4) correct
- 17. Momentum: when m and V are constant, only the direction of V changes, then the momentum changes
- 18. The kinetic energy of electron is equal to the static energy. What's the wavelength?
- 19. As shown in the figure, the length of the uniform thin straight bar AB is l, the mass is m, and the instantaneous velocity of point a is V, then the momentum of the bar AB is? What about kinetic energy?
- 20. If two objects have the same momentum, they must have () A. the same velocity B. the same mass C. the same direction of motion If two objects have the same momentum, they must have () A. Same speed B. same mass C. Same direction of motion D. same acceleration