materials: a plastic cup, a cup of rice and a bamboo chopstick
operation:
1. Fill the plastic cup with rice.
2. Press the rice in the cup by hand.
3. Hold the rice with your hands and insert chopsticks between your fingers.
4. Gently lift the chopsticks with your hands, and the cup and rice are lifted together.
Explanation:
Because of the extrusion between the rice grains in the cup, the air in the cup is squeezed out, and the pressure outside the cup is greater than the pressure inside the cup, so that the chopsticks and the rice grains are tightly combined, so the chopsticks can lift the cup with rice.
. The power of paper
Material: one glass, water, paper
Operation:
1. Fill the glass with water (be sure to fill it)
2. Cover the glass mouth with paper, and completely cover the glass mouth.
3. Turn the glass upside down
4. Water will not flow down
Explanation:
After step 2, the atmospheric pressure inside the cup is less than the atmospheric pressure outside the cup, so the atmospheric pressure outside the cup pushes the water into the cup to prevent the water from flowing out.
triboelectrification
Preparation equipment: tissue paper, pencil
Steps:
1. Tear the tissue paper to pieces as much as possible
2. Rub the pencil back and forth on the hair for n times
3. Put the rubbed pencil close to the pile of scraps of paper
Phenomenon: scraps of paper are sucked up by the pencil
Conclusion: Some scraps of paper are easy to electrify.
charged newspaper
Thinking: Without glue, adhesive tape and other things, the newspaper can stick to the wall and not fall off. Do you know why?
material: 1 pencil; 1 newspaper.
Steps:
1. Expand the newspaper and lay it flat on the wall.
2. After rubbing the side of the pencil on the newspaper a few times quickly, the newspaper can't fall off as if it were stuck to the wall.
3. Lift a corner of the newspaper, then let go, and the lifted corner will be sucked back by the wall.
4. Remove the newspaper from the wall slowly, and pay attention to the static sound.
Description:
1. Rub the pencil to make the newspaper charged.
2. The charged newspaper was sucked to the wall.
3. When the air in the room is dry (especially in winter), if you take off the newspaper from the wall, you will hear the crackle of static electricity.
creation: please try it. What other things can be stuck to the wall by static electricity without adhesive?
Separation of pepper and salt
Thinking: The kitchen condiments, pepper and salt, are accidentally mixed together. How can they be separated?
materials: pepper, salt, plastic spoon and small plate
operation:
1. mix salt and pepper together.
2. Stir well with chopsticks.
3. The plastic spoon is rubbed on the clothes and placed above the salt and pepper.
4. Pepper sticks to the spoon first.
5. Move the plastic spoon down a little.
6. Salt and stick to the spoon.
Explanation:
The reason why pepper is electrostatically adsorbed earlier than salt is because its weight is lighter than salt.
Creation:
Can you separate other mixed raw materials in this way?
charged balloons
Thinking: When will two balloons attract each other and when will they repel each other?
materials: 2 inflated balloons, 1 piece of string and 1 piece of cardboard
operation:
1 inflate the two balloons separately and tie a knot on the mouth.
2 connect two balloons with a thread.
3 Rub the balloon on the hair (or sweater).
4 lift the middle part of the string, and the two balloons will be separated immediately.
5 put the cardboard between two balloons, and the electricity on the balloons makes them attracted to the cardboard.
explanation:
1 The electricity on one balloon repels the electricity on the other balloon.
the electricity on the two balloons attracted them to the cardboard.
Creation: Can you use other small experiments to illustrate whether the balloon is charged?
Lovely watermark
Thinking: The beautiful patterns on rice paper are not drawn, but how are they made?
materials: 1 washbasin, 1-2 pieces of rice paper, 1 chopstick, 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 the water surface with the chopsticks dipped in ink, and you can see that the ink expands into a circle on the water surface.
2. Rub a cotton swab on the scalp two or three times.
3. Then gently touch the center of the ink circle pattern to see what happens.
4. Cover the calligraphy paper gently on the water, and then slowly pick it up. What patterns are printed on the paper?
explanation:
1. When the cotton swab touches, the ink will be expanded into an irregular circle.
2. A small amount of oil coated by cotton swab rubbing on scalp will affect the 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.
On-off water flow
Thinking: Why do multiple water flows turn into one water flow with a touch of your hand?
material: a tin can box, awl, water
operation:
1. Use a nail to drill five small holes in the bottom of the empty tin can box (the interval between the small holes is only about 5 mm).
2. Fill the tank with water, which flows out of five holes in five streams.
3. Twist these streams together with your thumb and forefinger.
4. When the hand is removed, five strands of water will be combined into one.
5. If you wipe the small hole in the can with your hand again, the water will become five strands again.
explanation:
the surface tension of water makes the water flow separate and combine.
floating needle
Thinking: Why does the needle float on the water?
materials: a bowl of water, needle, fork and liquid detergent
Operation:
1. Pour a glass of clean water into the cup
2. Carefully put a needle on the surface of the water with a fork
2. Slowly remove the fork, and the needle will float on the water
3. Drop a drop of detergent into the water. Surface tension is a 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 a film. This film is called surface tension, which can hold the object that should have sunk.
2. The detergent reduces the surface tension, so the needle will not float.
description: the needle is dangerous, please ask your 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 and sugar cubes
operation:
1. put the toothpick on the water carefully.
2. Put the sugar cubes in the basin far away from the toothpicks. The toothpick will move in the direction of the sugar cube.
3. 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.
Explanation:
When you put the cube into the center of the basin, the cube 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 relatively strong, so you will pull the toothpick outward.
Creation: Please try. If sugar and soap are replaced by other substances, which direction will the toothpick swim?
Perforated paper holds water
Thinking: Why can perforated paper hold water?
materials: a bottle, a pin, a piece of paper, and a full cup of colored water
Operation:
1. Fill the empty bottle with colored water.
2. Punch many holes in the white paper with a pin.
3. Cover the bottle mouth with perforated paper.
4. Press the paper with your hand, and turn the bottle upside down so that the mouth of the bottle faces down.
5. Gently remove your hand, and the paper will cover the bottle mouth without moving, and water will not flow out of the hole.
explanation:
the thin paper can hold up the water in the bottle because the atmospheric pressure acts on the paper, resulting in upward pulling force. Water will not leak from the small holes because water has surface tension, and water forms a film of water on the surface of the paper, so that water will not leak out. This is like an umbrella made of cloth. Although the cloth has many small holes, it still won't leak rain.
The secret of handkerchief
Thinking: Open the handkerchief under the faucet and turn on the faucet. Does the water flow through the handkerchief?
Materials: 1 glass, 1 handkerchief and 1 rubber band
Process:
1. Cover the cup with a handkerchief and tie it tightly with a rubber band.
2. Let the water flush 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 quickly.
Description:
1. When the water is flushed from the top of the cup, the water will flow into the cup through the handkerchief.
2. When the cup is turned upside down, water will not flow out due to the atmospheric pressure.
extension:
if the handkerchief covering the cup mouth is made of different materials (such as cotton cloth or towel or linen), what will happen to the water in and out?
Plastic pad that can't fall down
Thinking: The cup containing water is covered with a pad. Will the pad fall down when the mouth of the cup is facing down?
materials: two glasses, water and a plastic plate
operation:
1. fill the glass with water.
2. cover the cup mouth with a backing plate.
3. Hold the cup with one hand and press the pad with the other.
4. Hold it with your hand and turn the cup mouth upside down.
5. Let go of the hand holding the pad gently, so that the pad will not fall off.
Explanation:
The pad covers the mouth of the cup containing water, because the air pressure outside the cup is relatively high, so the pad will not fall off.
Creation:
What happens if the water in the cup is not enough or there is no plastic board? Please try it.
candles can't be extinguished
Thinking: Blow a burning candle hard, but it can't be extinguished. Do you know how to do this?
materials: 1 candle, 1 match, 1 small funnel and 1 flat plate
operation:
1. light the candle and fix it on the flat plate.
2. Make the wide mouth of the funnel face the flame of the candle, and blow hard at the flame from the small mouth of the funnel.
3. Make the small mouth of the funnel face the flame of the candle, and blow hard against the flame from the wide 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 end of the funnel, the candle will be easily extinguished.
2. The blown gas gradually evacuates from the narrow mouth to the wide mouth, and the air pressure decreases. At this time, the gas around the wide mouth of the funnel will flood into the wide mouth of the funnel because of the strong air pressure. Therefore, the flame of the candle will also rush to the wide mouth of the funnel.
note: pay attention to the safety of candles when burning.
candle pump
Thinking: Do you know how the pump pumps water?
materials: glass, candle, cardboard slightly larger than the mouth of the glass, plastic pipe, a little vaseline, matches and half a cup of water
Operation:
1. First, fold the plastic pipe into the shape of a door frame, with one end passing through the cardboard
2. Then put the two glasses on the table one by one
3. Light the candle and fix it at the bottom of the left glass.
5. Water flows into the left cup from the right
Explanation: The oxygen in the left cup is used for candle burning, and the air pressure in the bottle is reduced. 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 of the left cup is higher than that of the right cup.
Attention: Pay attention to safety when lighting the candle and then fixing it at the bottom of the left glass, and be careful to burn your hands
Blow up the balloon in the bottle
Thinking: Why don't you loosen the balloon mouth and the balloon won't get smaller?
material: large-mouthed glass bottle, two straws: red and green, one balloon and one air pump
Operation:
1. Punch two holes in the bottle cap in advance with a screwdriver. Insert two straws in the hole: red and green
2. Tie a balloon on the red straw
3. Cover the bottle cap on the bottle mouth
4. Blow up the balloon at the red straw with an air pump
5. Release the red straw and the balloon will become smaller immediately
6. Blow up the balloon at the red straw with an air pump
7. Pinch it quickly. However, after the balloon is shrunk, the air volume in other parts of the bottle is enlarged, and the green tube is closed. As a result, 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.
Cup that can catch the balloon
Thinking: Would you use a small cup to gently invert the balloon sphere and then suck it up?
materials: 1 ~ 2 balloons, 1 ~ 2 plastic cups, 1 thermos bottle and a little hot water
Process:
1. Blow the balloon and tie it
2. Pour hot water (about 7℃) into the cup for about half a cup
3. After the hot water stays in the cup for 2 seconds, pour the water out
.
2. The cup treated with hot water can suck up the balloon because the air in the cup is gradually cooled and the pressure is reduced.
Extension:
Children, please think about other ways to suck up the balloon.
A cup that absorbs water
Thinking: Cover the burning candle with a glass. What happens in the cup after the candle is extinguished?
materials: 1 glass (higher than candle), 1 candle, 1 flat-bottomed plate, 1 lighter and some water
Operation:
1. Light the candle and drop a few drops of wax oil in the center of the plate to fix the candle.
2. Fill the plate with water about 1 cm high.
3. Invert the glass on the candle
4. Observe the candle burning and the change of water level in the plate
Explanation:
1. After the air (oxygen) in the glass is consumed, the candle flame goes out.
2. After the candle goes out, the water level in the cup will gradually decrease.