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Anonymous users2024-02-081. It's better for you to ask this question, roughly: air resistance, the friction of the wire rope, are all there, so this is generally good. You're right.
2. Of course, you are in the elevator, although you are not in free fall, but there is only a little bit of air resistance, and your acceleration = g-f m; g acceleration due to gravity, f negligible air resistance (if the elevator is closed, f = 0, m its own weight.
Acceleration of elevator = g-(f1+f2) m; G gravitational acceleration, F1 air resistance, F2 wire rope friction, I don't want to write anymore, there are many other forces, for example, the weight balance of the wire rope and other factors, all in it, the above is the elevator free fall, your acceleration in the elevator, and the counterweight is broken, the acceleration of the elevator, if you look at it as a whole, you break the counterweight in the elevator, then your acceleration is greater than the acceleration of the elevator, and the elevator will give you a certain supporting force, that is, F1+F2-F. It's not a lot of power, but it exists, and you can't reach the realm of a spaceship yet.
3. The way you said can maximize the possibility of your survival, you are not weightless, the bottom of the elevator is strong in supporting you, can do it, I am not engaged in the elevator, but I am engaged in safety, there are many protective devices in the elevator, especially the ladder protection device is a must, you can rest assured, if the elevator falls, the fall will not be too high will be stuck, you just use your legs to bear the moment of the card The elevator supports you.
4. This problem is more difficult, the reaction ability depends on the person itself, the elevator will not fall, it will be stuck, if you want the time to fall from the 16th floor, you calculate it this way, s=gt 2;s is the height m, g = approximate value of the acceleration in the state of free fall) to find t, this time is calculated to be smaller than the actual time, you can use it as a reference.
5. It's not that the acceleration is greater when falling, the more uncomfortable it is, but the moment when you get stuck is the most uncomfortable, because you have to bear several times the upward gravitational acceleration.
Pure hand-hitting, although there is no authoritative verification, but it is sure to be correct, hope, thank you.
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Anonymous users2024-02-07Generally speaking, as long as the elevator of the building meets the safety regulations (I don't know what the regulations are, at least there are standards in Taiwan), when the elevator breaks the cable and loses weight, the brake outside the elevator car will automatically turn on (this is a mechanical device that does not require power supply), and the bottom of the shaft also has anti-collision shock absorption equipment. In other words, even if the cable suddenly breaks and falls, the elevator car will not be completely weightless; Even if it falls to the lowest level, it will not directly hit the ground. So we have never heard of people falling to death in the elevator, at most only the abrasions caused by the swaying, and other problems caused by power outages.
Therefore, what is more dangerous is not what happens when people are in the elevator car, but when people want to enter the elevator, the outer door has been opened, but the carriage has not reached the floor positioning; If the user does not pay attention, he or she will step into the intended (but non-existent) elevator car and fall directly down the shaft because he or she steps on the air. This kind of fall to death is real, because the danger of unintended is even greater.
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Anonymous users2024-02-06Answer: C solution: The velocity of A relative to the still water is v, and the velocity of B relative to the still water is v
Taking the shore as the reference, the velocity of the water flow is vo, the velocity of A is (v+vo), the velocity of B is (v-vo), A travels in the same direction as the floating object, and the velocity of A relative to the floating object is (v+vo)-vo, B travels in opposite directions with the float, and the velocity of B relative to the floating object is (v-vo)+vo
The distance between A and the float is s, and the distance between B and the floater is s.
The time taken by A to catch up with the floating object is t1=s (v+vo)—vo =s v, and the time for B to meet the floating object is t2=s (v—vo)+vo =s vt1=t2
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Anonymous users2024-02-05That's a lot, like.
1.The friction force of a person when walking.
2.The finish line timekeeper of a long-distance race starts by seeing the smoke from the starting pistol3Lightning is seen first and thunder is heard.
4.It is not easy to separate the glass after sticking to water.
5.White smoke from hot water.
6.Rainbow. 7.In winter, a layer appears on the windows"Ice flowers"
8.B-ultrasound.
9.Water boiling phenomenon.
11.Mothballs become smaller over time.
12.Ultrasonic dishwasher.
13.Glowing light bulbs.
14.Proverb"It's cold before frost and cold after snow"
15.Cook rice in a pressure cooker quickly.
16.Blow into a hot soup bowl to cool down.
17.It will feel cool when you blow the electric fan.
18.You will feel cold after swimming ashore.
19.Warm your hands with a sigh of air.
20.There is always a layer of dust on the TV.
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Anonymous users2024-02-04Answer: When pouring water into a thermos, the sound you hear is different because the tone is related to the vibrational frequency of the emitter: the higher the frequency, the higher the tone;
When a person who wears glasses enters a warm room from a cold outside, the spectacle lenses will fog up because the water vapor in the indoor air liquefies into small water droplets on the lenses;
The soccer ball in the air ends up on the ground because it is affected by gravity, and the direction of gravity is straight down
No contradiction You misunderstood that molecules that attract each other do not fit close together when the distance between molecules d=r gravitational force = repulsive force; In other words, "the experiment of the lead blocks close together shows that there is a gravitational force between the molecules", and the distance between the molecules must be at least greater than r, how can they be close together?
Personally, I understand it.
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Here comes the standard answer.
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