Paid newspaper
Thinking: Without glue, tape and other things, newspapers can stick to the wall without falling off. Do you know why? Material: 1 pencil; 1 newspaper. Step: 1. Spread the newspaper out and lay it flat on the wall. 2. After a few quick rubs on the newspaper with one side of the pencil, the newspaper won't fall off just like sticking to the wall. 3. Lift a corner of the newspaper, and then let go, and the lifted corner will be sucked back by the wall. Take the newspaper off the wall slowly and pay attention to the static sound. Description: 1. Rubbing a pencil charges the newspaper. 2. The charged newspaper was sucked to the wall. When the indoor air is dry (especially in winter), if you take down the newspaper from the wall, you will hear the crackle of static electricity. Creation: Please try it. What else can be stuck to the wall by static electricity without glue? Thoughts on the separation of pepper and salt: I accidentally mixed the kitchen seasoning: pepper and salt. How can I separate them? Ingredients: pepper, salt, plastic spoon, small dish operation: 1 Mix the salt and pepper together. 2. Stir well with chopsticks. 3. Rub the plastic spoon on the clothes and put it on the salt and pepper. 4. Pepper sticks to the spoon first. 5. Move the plastic spoon down slightly. 6. After salt, stick it on the spoon. Explanation: Pepper is electrostatically adsorbed earlier than salt because its weight is lighter than salt. Creation: Can you separate other mixed raw materials in this way? Reflections on charged balloons: When will two balloons attract each other and when will they repel each other? Material: 2 inflatable balloons, 1 string, 1 cardboard. Operation: 1 Inflate two balloons separately and tie a knot in your mouth. Connect two balloons with a thread. Rub the balloon on your hair (or sweater). Lift the middle part of the rope and the two balloons will separate immediately. Put the cardboard between two balloons, and the electricity on the balloons makes them attracted to the cardboard. Description: 1 The electricity on one balloon repels the electricity on the other balloon. The electricity on the two balloons attracts them to the cardboard. Creation: Can other small experiments be used to illustrate that balloons are charged?
Lovely watermark
Thinking: The beautiful patterns on rice paper are not drawn, but how are they made? Material: 1 washbasin, 1-2 rice paper, 1 chopsticks, 1 cotton swab, 1 bottle of ink and water (about half a basin) Operation: 1. Pour half a basin of water into the washbasin and gently touch it with chopsticks dipped in ink. 2. Wipe the scalp with a cotton swab for two or three times. 3. Then touch the center of the ink circle and see what happens. 4. Gently cover the calligraphy paper on the water, and then pick it up slowly. What patterns are printed on the paper? Explanation: 1 When the cotton swab touches, the ink will expand into an irregular circular pattern. 2. A small amount of oil on the scalp rubbed by cotton swabs will affect the mutual pulling force of water molecules. 3. The watermark will present irregular concentric circles. Creation: Try other methods to change the ink pattern on the water surface. Think about the intermittent water flow: why do many streams of water become one when you touch them with your hand? Material: a tin box, awl, water operation: 1. Drill five holes in the bottom of the empty tin can box with nails (the spacing between the holes is only about 5 mm). 2. Fill the water tank with water, and five streams of water flow out from five small holes. Twist these streams together with your thumb and forefinger. When the hand is removed, the five streams of water will merge into one. If you wipe the small hole in the jar with your hand again, the water will become five strands again. Description: The surface tension of water separates and closes the water flow.
Floating needle
Thinking: Why does the needle float on the water? Material: a bowl of water, needle, fork and liquid cleaner. Operation: 1. Pour a glass of water into the cup. Carefully put a needle on the water with a fork. Move the fork slowly, and the needle will float on the water. Drop a drop of detergent into the water and the needle will sink. Explanation: 1 It is supported by the surface tension of water. Surface tension is the cohesive connection formed by water molecules. This cohesive connection is due to the fact that some molecules are attracted together and the molecules squeeze each other to form films. This kind of film is called surface tension, which can hold the object that should sink. 2, detergent reduces the surface tension, the needle will not float. Attention: The needle is dangerous, please ask parents to help you operate it.
Magic toothpick
Thinking: Will the toothpick in the water swim with the sugar cubes in the water or with the soap in the water? Materials: toothpick, a basin of water, soap, sugar cube operation: 1. Carefully put the toothpick on the water. 2. Put the sugar cubes in the basin, away from the toothpicks. The toothpick will move towards the sugar cube. Change a basin of water, carefully put the toothpick on the water, and now put the soap in the basin near the toothpick. Toothpicks will stay away from soap. Note: When you put the cube in the center of the basin, it will absorb some water, so there will be a small water flow in the direction of the cube, and the toothpick will move with the water flow. However, when you put soap into the basin, the surface tension at the edge of the basin is strong, so you will pull the toothpick out. Creation: Please try. If sugar and soap were replaced by other substances, in which direction would the toothpick swim to the perforated paper to hold water? Why can perforated paper hold water? Material: a bottle, a pin, a piece of paper, a full cup of colored water. Operation: 1. Fill the empty bottle with colored water. Punch many holes in the white paper with a pin. 3. Cover the bottle mouth with perforated paper. 4. Hold the paper with your hand, turn the bottle upside down, and make the bottle mouth face down. Gently remove your hand, the paper will cover the bottle mouth and the water will not flow out of the hole. Description: Tissue paper can hold up the water in the bottle because atmospheric pressure acts on the paper, resulting in upward tension. Water will not leak out from the small holes because water has surface tension, and water forms a water film on the surface of paper, so water will not leak out. This is like an umbrella made of cloth. Although this cloth has many holes, it still won't leak rain.
The secret of handkerchief
Thinking: Lay the handkerchief flat under the faucet and turn on the faucet. Does water flow through the handkerchief? Material: 1 glasses, 1 handkerchief, 1 rubber band. Process: 1. Cover the cup with a handkerchief and tie it tightly with a rubber band. 2. Let the water flow on the handkerchief. 3. Turn off the tap after the water flows into the cup for about seven or eight minutes. 4. Turn the cup upside down. Description: 1. When flushing from the top of the cup, water will flow into the cup through the handkerchief. 2. When the cup is inverted, water will not flow out due to atmospheric pressure. Extension: If the cloth covering the handkerchief is different (such as cotton cloth or towel or linen), what will happen to the water coming in and out? Thinking about the plastic mat that can't fall off: cover the cup filled with water with a mat. Will the cushion fall off when the cup mouth is facing down? Materials: two glasses, water and a plastic plate. Operation: 1. Fill the glass with water. 2. Cover the cup with a pad. Hold the cup in one hand and the mat in the other. 4. Hold it by hand, turn the cup mouth upside down, and let the cup mouth face down. Let go of the hand holding the pad gently, and the pad won't fall off. Note: The cushion covers the mouth of the cup filled with water, because the air pressure outside the cup is relatively high, and the cushion will not fall off. Creation: What happens if there is not enough water in the cup or there is no plastic board? Please try it. Candles can't go out. Thinking: Blow out the burning candle hard, but it can't be extinguished. Do you know how to do it? Material: 1 candle, match, 1 funnel, 1 tablet operation: 1. Light candles and fix them on the flat. 2. Let the wide mouth of the funnel face the flame of the candle, and blow the flame forcefully from the small mouth of the funnel. 3. Let the small mouth of the funnel face the flame of the candle, and blow the flame forcefully from the big mouth of the funnel. Explanation: 1 When blowing in this way, the flame will be inclined to the wide mouth end of the funnel and will not be easily blown out. If you blow from the wide mouth of the funnel, the candle will go out easily. 2. The blown gas gradually empties from the narrow mouth to the wide mouth, and the air pressure is weakened. At this time, the gas around the funnel wide mouth will flow into the funnel wide mouth because of the strong air pressure. Therefore, the flame of the candle will also rush to the wide mouth of the funnel. Attention: Pay attention to the safety of candles when burning.
Candle pump
Thinking: Do you know how the pump pumps water out? Materials: glass, candles, cardboard slightly larger than the glass mouth, plastic pipe, a little vaseline, matches and water. Half cup operation: 1. First, the plastic pipe is folded into the shape of a door frame, and one end passes through the cardboard. Then put two glasses on the table one by one. 3. Light the candle, fix it at the bottom of the left glass, and inject water into the right glass at the same time. 4. Put some vaseline on the glass mouth where the candle is placed, and then use it. 5. Water flows into the cup on the left from the right. Description: When the candle burns, there is oxygen in the left cup, and the air pressure in the bottle decreases. The pressure in the right cup makes the water flow to the left cup until the pressure on the water surface of the two cups is equal. At that time, the water level in the left cup was higher than that in the right cup. Note: Pay attention to safety when lighting the candle and then fixing it at the bottom of the left glass. Be careful to burn your hand and blow the balloon in the bottle. I thought: Why don't you loosen the balloon mouth so that the balloon won't get smaller? Materials: large glass bottle, two straws: red and green, one balloon, air pump operation: 1, punch two holes in the bottle cap with a screwdriver in advance, and insert two straws in the holes: red and green. Tie a balloon on the red straw. 3. Cover the bottle cap on the bottle mouth. 4. Inflate the balloon at the red straw with an air pump. 5. Loosen the red straw and make it smaller immediately. 6. Inflate the balloon at the red straw with an air pump. 7. Quickly pinch the two nozzles of the red straw and the green straw. Loosen the red straw nozzle. Balloons don't get smaller. Explanation: When the red straw is released, the rubber film of the balloon shrinks. But after the balloon is deflated, the air volume in other parts of the bottle becomes larger and the green tube is closed. In this way, the air pressure in the bottle will be reduced-even lower than that in the balloon. At this time, the balloon will not continue to shrink.
A cup that can catch a balloon
Thinking: Is it right to gently invert a small cup on the spherical surface of the balloon and then suck it up? Materials: 1 ~ 2 balloons, 1 ~ 2 plastic cups, 1 thermos bottle, a little hot water flow: 1. Blow up the balloon and fasten it. 2. Pour hot water (about 70℃) into about half of the cup. 3. After the hot water stays in the cup for 20 seconds, immediately pour out the water. 2. For the cup treated with hot water, the balloon can be sucked up because the air in the cup is gradually cooled and the pressure is reduced. Extension: children, please think about what else you can do to suck up the balloon. Think about a cup that can absorb water: cover a burning candle with a glass. What happens in the cup when the candle goes out? Materials: 1 glass (higher than candle), 1 candle, 1 flat plate, 1 lighter, water. Partial operation: 1. Light the candle and fix the candle with a few drops of wax oil in the center of the plate. 2. Fill the plate with water about 1 cm high. 3. Invert the glass on the candle. 4. Observe the burning of candles and the change of water level in the dish. Explanation: 1 After the air (oxygen) in the glass is consumed, the candle flame goes out. When the candle goes out, the water level in the cup will gradually rise. Creation: Can I collect other solutions automatically with empty containers?
A bottle that can eat eggs
Thinking: Why can eggs enter from bottles smaller than themselves? Materials: 1 boiled egg, 1 narrow-mouth bottle, several pieces of paper, 1 match. Operation: 1. Peel the shell of an egg. 2. Tear the paper into strips. 3. Light the note and throw it into the bottle. As soon as the fire goes out, buckle the egg to the bottle mouth and take your hand away immediately. Explanation: 1, the paper has just been burned and the bottle is hot. 2. After the egg is buckled in the bottle mouth, the temperature in the bottle gradually decreases, the pressure inside the bottle becomes smaller, and the pressure outside the bottle becomes larger, so that the egg will be squeezed into the bottle. Creation: What will happen to the bottle when the gas pressure inside the bottle is greater than the pressure outside the bottle? The bottle is flat. Thinking: Can you deflate plastic bottles without hands? Materials: 2 cups of water, 1 cup of warm water, 1 mineral water bottle. Operation: 1. Put warm water in the bottle and touch the bottle with your hand to see if it feels hot. 2. Pour the warm water out of the bottle again and quickly cover the bottle cap. 3. Watch the bottle deflate slowly. Explanation: 1 Heat the air in the bottle to reduce its pressure. 2. Because the air pressure outside the bottle is greater than the air pressure inside the bottle, the bottle is crushed. Creation: What would the bottle look like if the pressure of the gas inside the bottle was greater than the pressure of the air outside the bottle?
Table tennis capable of long jump.
Thinking: Ping-pong is put in a goblet. How to blow to make the ball jump out of the goblet? Materials: 2 goblets, table tennis 1 Operation: 1 Put two goblets side by side and put two table tennis balls in the first cup. Blow from different angles to see what table tennis is like: blow on the side of the ball; Blowing at the top of the ball: 1, blowing at the side of the ball, table tennis is not easy to jump into the second cup (or jump out). 2. Blowing at the top of the ball will reduce the pressure on the top of the ball, and table tennis will float. Continue blowing and jump into the second cup. Creation: A new method can also make table tennis jump into the next cup. Thinking: Do you know how bottles blow bubbles? Materials: 1 beverage bottle, 1 cup of hot and cold water, 1 cup of colored water, 1 large plate, 1 piece of plasticine and straw. Several operations: 1 Connect the straws one by one to form a long tube (the connection port is sealed with adhesive tape). Put the straw in the bottle, seal the bottle with plasticine, and then put the bottle on the plate. 3 Bend the straw so that the other end of the straw enters the glass filled with colored water. Pour hot water on the bottle wall, and the straw in the cup will emit many bubbles. Pour cold water on the bottle wall. The water in the cup will flow into the bottle through the straw. Explanation: 1 Because the plastic bottle is very thin, heat can enter the air inside the bottle through the bottle wall. The air in the bottle will expand when heated. Bubbles in water are air squeezed out of a bottle when air expands. The air in the bottle contracts when it is cold. When the air in the bottle contracts, water occupies the remaining space. Creation: Do you know the best way to open the bottle cap when it is too tight?