Case 1: Shooting and killing people is based on the principle that sound waves from different directions meet and cancel each other, so there is no gunshot.
As shown in the figure (at the end), A is the peak value? B is the trough, which is two sound waves in different directions. When the peaks and valleys meet, they cancel each other out and the sound disappears. Conversely, when the peaks and valleys meet, the sound will be enhanced. This is the murder case in the Chamber of Secrets. Why do you hear different shots when you open one window and two windows? ?
Case 2: The disappearance of fingerprints is based on the characteristics of dry ice. Granular dry ice particles are sprayed by high-pressure air on the working face to be cleaned, and different substances are separated at different contraction speeds by using the physical reflection of temperature difference. When the dry ice particles at -78℃ contact with the dirt surface, it will cause embrittlement and explosion, which will make the dirt shrink and loosen, and then the dry ice particles will instantly vaporize and expand 800 times. The strong peeling force of the product will quickly and thoroughly peel off the dirt on the metal surface. This is why fingerprints suddenly disappeared.
Case 3: Ghosts in the house are based on the principle of reflection and refraction of light. This is not difficult and easy to understand. ?
Case 4: The collision in Guo Liang is based on the law of conservation of momentum. Problems such as explosion or collision have the same feature that the interaction of objects occurs suddenly, and the interaction force is variable, with short action time and large force, which is far greater than the external force on the system, so it can be handled by the law of conservation of momentum.
Case 5: High-altitude strong acid. First of all, when the hydrogen balloon is on the ground, the internal pressure is greater than the external pressure, but the quality of hydrogen will not be reduced. When the hydrogen balloon floats in the air, the external pressure decreases and the gas expands, but the density decreases. So it will keep flying upwards. When the rubber can't bear the internal pressure, the balloon will explode?
Case 6: Mechanical homicide. This case has little to do with physical knowledge, but it uses the principle of conditioned reflex in biology. As a result of conditioned reflex, when the bell rings, a mouse thinks that someone is going to feed it and will run out to find food, so it touches the switch connected to the mechanical gripper, forming a case of automatically firing bullets to kill people. ?
Case 7: Mysterious charred corpse. In order to accelerate the burning of the corpse, phosphorus, a well-known combustion improver in chemistry, was used. Its physical property is that when white phosphorus is oxidized in the air until the accumulated energy on the surface makes the temperature reach 40℃, it reaches the ignition point of phosphorus and spontaneously ignites.
Case 8: Bomb fanatics use acoustic principles in physics. Quiet wave found a clue in the call from the bomb forecast. The spectrogram recorded by telephone combined with the physical properties of sound is frequency and amplitude, and there is a second sound source. After the musical instrument test, it is determined that it is yoga music. Moreover, according to the structural characteristics of the bomb, it was found that the bomb at the scene was made by someone who was studying electrical engineering in Australia. At the same time, the medical knowledge of hippocampus was used to finally determine the bomb disposal method.
Case 9: The principle of Feng Shui feud using radioactive elements to cause gene mutation.
Case 10: Missing incident. Physics is mainly concerned with explaining why a pervert doctor can still trace his wife to the place where she is protected by the police without a tracker. It turned out that he was apparently injecting drugs into his wife's needle, but in fact he was injecting a new ultra-miniature tracker into her body. This chip can be tracked by GPS, so a sick doctor can always know the location of the monitored person, that is, the location of his wife. In addition, Professor Jing also used the Doppler effect to calculate the wave source and frequency of electric waves and sound waves.
Case 10: scientific confrontation. ?
You can watch the TV series I wrote above, and you will find it easy to understand. It's hard to summarize.