Application of Plastic Bottle in Physical Experiment
Plastic bottles are very common items in life and are often treated as garbage. I often use plastic bottles in physics teaching. Using them to make teaching aids and guide students to do some physics experiments can close the relationship between physics and life, further make students feel "from life to physics, from physics to society", thus realizing the relationship between natural science, society and life. At the same time, it also cultivates students' creativity, imagination and strong interest in physics. It can also cultivate the awareness of environmental protection. I have created and collected some self-made teaching aids and designed experiments using plastic bottles, mainly from two aspects: first, the experiments directly using plastic bottles in physics teaching; The second is the experiment of improving plastic bottles.
? I. experiments that can be completed by directly using plastic bottles ? 1. Acoustics: Put some small paper scraps in the plastic bottle and knock on the plastic bottle to observe the beating of the small paper scraps, but the small paper scraps will not beat when not knocking. This shows that sound is produced by the vibration of objects. Water of different depths is filled in several identical plastic bottles, and then blowing air into the bottles with the mouth will produce sounds with different tones, which can explain the relationship between tones and frequencies. ?
2. Optics: Through plastic bottles filled with water, the characters on the book will become larger. This is the refraction of light. Put a proper amount of milk powder into a plastic bottle filled with water, tighten the bottle cap and shake it well. Shine the light from the laser pen through the bottom of the bottle to the bottle cap, and you will see the light beam propagating along a straight line, with obvious effect. Lay the flashlight on the table top, place the paper box in front of the flashlight, and the position should be such that the light beam of the flashlight cannot be seen in the horizontal direction. Fill the round plastic bottle with water, and place it horizontally next to the paper box and slightly higher than the paper box, so that the light beam of the flashlight can be seen, which can explain the principle of sunrise. Round plastic bottles filled with water can also be used as convex lenses.
? 3. Electricity: friction electrification and plastic non-conduction can be accomplished with plastic bottles.
? 4. Mechanics: Pinching, throwing and receiving bottles can explain the effect of force and the three elements of force. Putting water in a plastic bottle on a piece of paper, twitching the paper quickly while the bottle does not move can explain inertia. Tied plastic bottles with thread is a perpendicular line. There is static friction force when holding the bottle vertically without dropping it. Place the plastic bottle horizontally on the horizontal table top. The force difference between dragging and rolling is the difference between sliding friction and rolling friction. The force for dragging an empty bottle is smaller than that for full bottle of water, and the smaller the pressure, the smaller the friction force. Immersing empty plastic bottles into water gradually can realize that the magnitude of buoyancy is related to the discharged water and has nothing to do with the depth of objects in the water. The same plastic bottle has different quality when filled with water and alcohol because of different density. The empty bottle and the bottle filled with water are placed on the sponge, and then the bottle filled with water is placed on the sponge, and the depression of the sponge can be observed to explore that the effect of pressure is related to the pressure and the stress area. The plastic bottle is pinched and deformed, and then the bottle cap is tightly closed, so that the bottle does not restore to the original state; The plastic bottle is filled with water, and the bottle mouth is covered with hard paper, and then the bottle mouth is downward, and the hard paper can hold the water; Pour a small amount of hot water into the plastic bottle, shake it a few times, tighten the bottle cap quickly, and flush the bottle with cold water. The plastic bottle is crushed. Put the balloon into a plastic bottle and wrap the mouth of the balloon outward, then the balloon is not easy to blow up. These experiments can illustrate the existence of atmospheric pressure. Fill the plastic bottle with appropriate amount of sand, tighten the cover, and put it into the water. The bottle can sink vertically. By adjusting the amount of sand, the bottle can float or suspend vertically in the water, thus exploring the ups and downs of objects.
? Many experiments can be done by directly using plastic bottles, which will not be listed here. If plastic bottles are improved, more experiments can be completed and students' creativity can be better stimulated.
? Second, the plastic bottle can be simply improved to complete the experiment (a) drilling holes in plastic bottles:
(1) Drill several small holes at different heights on the side wall of the plastic bottle, pour water into the bottle, and compare the distance of water sprayed from the holes. It can be concluded that the liquid pressure is related to the depth, and the greater the depth, the greater the pressure.
(2) Drill two small holes about 5mm apart near the bottom of the plastic bottle with sewing needles, carefully pour clean water, and be careful not to be stained with water drops outside the bottle. You can see two separate trickle streams emerging from the two holes. Once you stroke the two small holes with your finger, the two streamlets merge into one because of the attraction between the water molecules. If the soapy water with higher concentration is poured continuously, the two streamlets that merge into one will split into two again in a short time.
(3) Drill a few small holes in the plastic bottle at will, and cover it tightly with the bottle cap after filling it with water. At this time, the water will not flow out. If the bottle cap is unscrewed, the water will gush out, with unexpected effect. If you put your hand over these holes and immerse the bottle in water, there will be no water in the bottle. If you don't cover yourself and immerse yourself in water, the bottle will be filled with water in a short time. These experiments can show the existence of atmospheric pressure.
(2) Insert a glass tube of moderate length into the bottle cap and seal it with Vaseline to prevent air leakage:
(1) Mark the scale on the glass tube, carefully blow in a section of red ink, then close the bottle cap to the plastic bottle, and a thermometer will be made.
(2) add a little red ink to the large half bottle of water in the plastic bottle, cover it tightly with the bottle cap, and blow air into the bottle to make the water rise above the bottle mouth along the glass tube. the atmospheric pressure can be observed to change with the height at different heights.
(3) Cover the plastic bottle tightly with this bottle cap, place it upside down and fix it on the iron stand, immerse the glass tube in a beaker filled with red liquid, lay a layer of degreased cotton on the bottom of the plastic bottle, drop a little ether, and you can see the red liquid rising along the glass tube, which can explain the existence of vaporization heat absorption and atmospheric pressure of the liquid.
(4) remove the bottom of the two plastic bottles, close the bottle mouth with this bottle cap, connect the glass tubes with latex tube, add water to the plastic bottles, and a connector is ready.
(5) Drill a small hole with a diameter of 3mm at the bottom of a plastic bottle with a larger volume, and cover it tightly with this bottle cap after filling it with water. The glass tube should be inserted into the water to a certain depth. At this time, the flow rate of water flowing out of the small hole is constant.
⑥ Cover the plastic bottle tightly with a bottle cap. The glass tube is connected to a section of latex tube. Drill several small holes in the plastic bottle and wrap several circles of iron wire around the bottle body to make the plastic bottle balance in the water. A submarine model is ready. Suction of air, submarine sank into the water, blowing into the bottle, submarine surfaced. If it is tied with a heavy object and sunk into the water, blowing into the bottle, the "buoy method" can be simulated to salvage the sunken ship. ?
(3) Cut off the bottom of the plastic bottle:
(1) Place a layer of rubber film on the cut place and press it into the water. The rubber film will sag, and the deeper in the water, the greater the degree of sag, indicating that there is pressure inside the liquid, and the greater the depth, the greater the pressure.
(2) put the bottle mouth down, put the ping pong ball on the bottle neck, pour water from above, even if the water is full, the ping pong ball will not float up. when the bottle mouth is blocked from below by hand, the ping pong ball will float up. This shows that buoyancy is the pressure difference between liquid and objects immersed in it.
(3) will cut off the place smooth, covered with a layer of rubber film, the bottle on the lighted candle, tapping the rubber film, you can see the candle flame tilt jitter, even extinguished. If you stick a small plane mirror on the rubber membrane, close the bottle cap tightly, and illuminate the small mirror on the membrane with a small flashlight in a dark room, you can see the reflected light spot on the white wall. People speak loudly to the rubber membrane. The vibration of the air causes the membrane to vibrate, driving the small mirror to vibrate, making the reflected light spot become a flashing light band, which varies with the strength and frequency of the sound. ?
Plastic bottles, which can be seen everywhere in our life, have many uses in physics teaching. For example, they can replace beakers, measuring cylinders, funnels, overflow cups and other experimental equipment. As long as we are good at discovery, careful observation, diligent thinking and courageous practice, we can certainly design more teaching aids and experiments. At the same time, actively guide students to explore and let students make it by themselves. In this way, students' interest in learning physics can be improved, their practical ability and innovative spirit can be cultivated, and more importantly, students can consciously apply physical knowledge to practice, solve practical problems, and truly embody the concept of physics everywhere around them.
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