Physics quiz "It's interesting!!!!" (9th grade)

Physics quiz for Grade 9 "It's Interesting!!!!" ! ?

1. The fox, running away from the dog pursuing her, often makes sudden movements to the side just when the dog is ready to grab her teeth. Why is it difficult for a dog to catch a fox?

2. Why should weeding not too sharply pull weeds from the ground, even when they are weakly retained in the soil?

3. How does a man fall when he stumbles and when he slips?

4. Why is it difficult to hold a live fish in your hands?

5. What fish are called living power plants?

6. On what physical phenomenon is the salting of tomatoes, cabbage, cucumbers and other vegetables based?

7. Stroking the cat in the dark with a dry palm, you can notice small sparkles that arise between the hand and the hair. What's going on here?

8. Why do electrified people get their hair up?

9. How do whales, walruses, seals, living in water with ever-floating ice, constantly maintain a high body temperature (38-40 C)?

10. Why do we smell flowers at a distance?

Answers:

1. The fox suddenly changes the direction of movement, the dog for some time by inertia moves in the original direction, so can not follow the fox.
2. With a sharp pulling, the roots of the plant do not have time to move and the stem breaks off. The remaining weed roots in the soil germinate quickly again.
3. When a person stumbles, the legs stop, and the torso continues to move, so the person falls face down. When a person slips, he falls mainly on his back.
4. Friction of the fish on the hand is small, so it slips out of the hands.
5. Electric eel, electric stingray, electric catfish.
6. Diffusion.
7. When stroking a cat, the hand is electrified with subsequent spark discharge.
8. Hair is electrified by the same charge. As you know, the charges of the same name are repulsed, so the hair, like the leaves of the sultan, diverge in all directions.
9. These animals have a subcutaneous fat layer that prevents rapid heat loss (fat is known to be a poor conductor of heat).
10. Flowers contain aromatic substances whose molecules diffuse into the air.

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