Ask for help Ask for examples of common applications of junior high school physics in life Thank you

Aiming, standing, laser collimation: the linear propagation of light.

Teapots, boiler level gauges, locks, horizontal tubes: connectors.

Perpendicular: The direction of gravity is always straight down.

Camera: At twice the focal length, the convex lens forms an inverted and zoomed out real image.

Slide projector: Between the two focal lengths and the one focal length, the convex lens forms an inverted magnified real image.

Magnifier: Within one focal length, the convex lens forms an upright magnified virtual image.

Use ultrasound to break stones into the body: sound waves have energy.

Thermometer: Thermal expansion and contraction of liquids.

Use water as a coolant: the specific heat capacity of water is larger.

Use rubber as the outer layer of the wire: Rubber is a good insulator.

Lever principle scissors.

Cutting things with a knife Force area Pressure is related to pressure.

Walking friction.

The momentum of the pile driver on the construction site is conserved in kinetic energy, in short, n is too much to say, it is used all the time.

The resistor passes through the current and will heat up the electric water heater.

You walk: Static rubbing.

Thornfish: Refraction of light.

When cooking in the kitchen, the knife is not fast, but it should be sharpened, which is the principle of reducing the force area to increase the pressure.

When washing clothes in a washing machine, electrical energy is converted into mechanical energy. The main component of the washing machine is the electric motor, which is made according to the principle that an energized conductor is subjected to force in a magnetic field.

Using the thermal effect of electric current, we have made rice cookers, electric mattresses, etc

Using the principle of lens imaging, optical instruments such as glasses and telescopes are made to serve us.

Using the pressure of the atmosphere, we make pumps, suction cup hooks, etc. For example, when the workers are building the wall, they often use the hammer line to check whether the wall is vertical, which is the principle that the direction of gravity is vertical downward; The lower end of the shuttlecock is made heavier, which is to lower the center of gravity to protect the feather during the fall; The driver of the car can continue to coast when the engine is turned off when going downhill, which is the use of gravity to save energy; In agricultural production, the seedling throwing technology also uses the direction of gravity to go straight down. Without gravity, the world would be unimaginable, water would not be poured into the mouth, people would not be able to fall back to the ground after jumping, flying dust would float in the air forever, and the whole natural world would be a cloud.

When teaching gravity, it is necessary to let students have a lively discussion, fully tap students' imagination, and know that gravity is closely related to the reality of our production and life. Friction is an important force, and it is widely used in the reality of social production and life. For example, when people walk, it is very difficult to walk on smooth ground, because the friction of the contact surface is too small; When the car skiddies uphill, sprinkle some rough stones or straw on the road, and the car can move forward smoothly, which is to increase the roughness and increase the friction; The sole is made into various patterns, which also increases the roughness of the contact surface and increases the friction; The roller skates worn by skaters are equipped with balls to change the sliding friction into rolling friction, so as to reduce the friction and increase the sliding speed; The purpose of adding lubricating oil to all kinds of machines is to reduce the friction between the gears and ensure the good operation of the machine.

It can be seen that the actual production and life of human beings are related to friction, and the beneficial friction should be fully utilized, and the harmful friction should be minimized.

The elastic force can be used to carry out a series of social production and life activities, and the force has size, direction and point of action. For example, tall buildings need to lay a solid foundation, and bridge design needs to accurately calculate the force of each part; Tug-of-war requires a thicker rope to prevent excessive tension from causing breakage; A thicker steel wire should be added to the center of the high-voltage line to support a larger erection span; The explosive power generated by the athlete in an instant, and so on.

All the appliances you use are made of applied physics.

Physics is a natural discipline with a long history, and physical science, as an important branch of natural science, not only plays an important role in promoting the progress of material civilization and the deepening of human understanding of the natural world, but also has an indispensable impact on the development of human thinking. From the natural philosophy of Aristotle's time, to the classical mechanics of Newton's time, to the theory of relativity and quantum mechanics in modern physics, they are all tangible manifestations of physicists' scientific quality, scientific spirit and scientific thinking. With the development of science and technology and the progress of society, physics has infiltrated into all fields of human life.

For example, just looking for optical knowledge in automobiles can do the following:

1 The rearview mirror on the outside of the car cab is a convex mirror.

The divergence of light from the convex mirror and the characteristics of upright, shrinking and virtual image are used to make the physical objects seen small and the observation range larger, so as to ensure driving safety.

2 The reflector in a car headlamp is a concave mirror.

It is made by using a concave mirror to reflect the light emitted by a light source placed on its focal point into the property of parallel light.

3. Automobile headlamps should always be equipped with horizontal and vertical striped glass lampshades.

Car headlights consist of a light bulb, a reflector, and a glass cover in front of the lamp. According to the knowledge of lenses and prisms, the glass cover of automobile headlights is equivalent to a combination of lenses and prisms. When driving at night, drivers must not only see the road ahead, but also the roadside holders, road signs, fork in the road, etc.

Lenses and prisms have a refractive effect on light, so the lampshade disperses the light to the desired direction according to the actual needs through refraction, so that the light evenly and softly illuminates the road and the roadside scenery of the car, and at the same time, this astigmatism lampshade can also make a part of the light slightly refracted upward, so as to illuminate road signs and milestones, so as to ensure driving safety.

4 With brown glass on the car, it is difficult for pedestrians to see the faces of the people in the car.

Brown glass reflects some of the light and absorbs some of it, so the light that penetrates into the car is weak. In order to see the passenger's face clearly, the light reflected from the face must be strong enough to be transmitted to the outside of the glass. Due to the low light in the car, not enough light is transmitted through, so it is difficult to see the faces of passengers.

5 With the exception of large passenger cars, the front windows of most cars are slanted.

When the front window glass of the car is tilted, the passengers in the car are reflected by the glass into the image of the front of the country, and the pedestrians on the road are unlikely to appear in the air above, so that the image of the passengers in the car is separated from the pedestrians on the road, and the driver will not have the illusion. Large passenger cars are larger, and the front window is much higher from the ground than a small car, even if the front window is installed vertically, as if it is the same height as the window, and pedestrians on the road cannot appear at this height, so the driver will not confuse the image of passengers outside the window with pedestrians on the road.

1.There is no signal from the mobile phone in the elevator: metal can shield electromagnetic waves2Vocal cord vibration when living: Objects vibrate and make sounds.

3.Boil water, when the water boils, the spout appears "white gas", fog: water vapor liquefaction 4Money detector: Ultraviolet light can make fluorescent substances glow.

5.Mirror: The reflection of light.

6.Cameras, projectors, magnifying glasses: the refraction of light.

7.Myopic eye (imaged in front of the retina): concave lens.

8.Hyperopia (like behind the retina): convex lens.

9.Smell the flowers from afar: molecules in the never-ending regular movement of crops10Nuclear power plants, atomic bombs: nuclear fission.

11.Sun: Nuclear fusion.

12.Straws, pressure cookers: atmospheric pressure.

13.Ships, submarines, balloons, airships: buoyancy.

14.Seesaw: Leverage.

15.The car also slides forward for a distance when it comes to a sudden stop: everything has inertia16Ring Road: Slopes.

17.The temperature difference between day and night in coastal cities is smaller than that in inland areas: the specific heat capacity of water is greater than that of sediment by 18Motor: The energized coil rotates under force in a magnetic field.

19.Generator: Electromagnetic induction phenomenon.

20.Kettle: The thermal effect of electric current.

Car brakes, monkeys fishing for the moon, looking in the mirror, flashlights, boats, scales. And so on and so forth.

brakes, winding roads, and more.

The atmospheric pressure during breathing is the exchange of air in the lungs.

If you look for 50 things, you may have 50 examples of the application of physics knowledge in real life.

Let me give you two examples.

Bicycles: Bicycle handlebars, plate rotation rights, force arms, torques.

Bicycle bells, vibrating sounds.

Bearing, rolling friction is less than sliding friction, bicycle brake, sliding friction is greater than rolling friction, bicycle chain is connected to the crankset and flywheel, the same linear speed produces different angular velocity bicycle flywheel and wheel, the same angular velocity, different linear velocity at the edge, etc. Guitar:

The thickness, length, and tension of the strings are different, the natural frequency is different, the resonance box is different, and the sound resonance.

The difference between the light and heavy sound of the plucked strings is related to the amplitude of the sound energy.

Wait a minute. There should be a lot of them looking for it this way.

It's not going to be a homework.

Amplitude affects loudness, the so-called amplitude refers to the amplitude of the vibration, loudness refers to the volume, and the loud voice we say refers to the loudness.

For example, if the strings are gently plucked, and the heavy plucking, the amplitude is different, and the loudness is also different.

Frequency affects tone, and the so-called tone refers to what we call bass, soprano.

This high and low refers to the pitch.

Frequency refers to the speed of the vibration, the faster the vibration, the higher the adjustment, you put your hand on your throat, make a high and low sound, feel the speed of the vocal cord vibration.

Put a ruler on the edge of the table, and find that the greater the amplitude, the louder it is.

The male voice is deep and the female voice is sharp, and the reason is that the female larynx is thinner than the male and has a large amplitude, so the pitch is high.

I only want to come up with so much for the time being...

The amplitude of the sound source is related to loudness, and the frequency is related to the pitch.