First of all, the bottle competition
Thinking: Two bottles of the same weight, one filled with sand and the other filled with water, roll down from a height. Who will reach the finish line first?
Materials: two bottles of the same size and weight, sand, water, a rectangular board and two thick books.
Operation:
1. Make a slope with a rectangular board and two books.
2. Pour water into another bottle and sand into the bottle.
3. Put two bottles on the board and let them roll down at the same starting height.
The bottle filled with water reaches the finish line earlier than the bottle filled with sand.
Explanation:
The friction between sand and the inner wall of the bottle is much greater than that of water, and there will be friction between sand, so its sliding speed is slower than that of a bottle filled with water.
Second, paid newspapers.
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.
Steps:
1. Spread the newspaper 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 like it is stuck on the wall.
3. Lift a corner of the newspaper, and then let go, and the lifted corner will be sucked back by the wall.
4. Slowly take down the newspaper from the wall and pay attention to the static sound.
Description:
1. Rub the pencil to charge 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.
Third, the separation of pepper and salt
Thinking: I accidentally mixed the kitchen condiments: pepper and salt. How can I separate them?
Ingredients: pepper, salt, plastic spoon, small dish.
Operation:
1. Mix salt and pepper.
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.