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Is the normal force is a kind of force we can't feel? It is just for us to find and recognise what apparent weight is, isn't it? [MATH] \Sigma F_n=ma [/MATH] By the way, when will it be taught?(Due to the difference in educational system, I'd better seek for the age of learning) thank you

Should it be classified in the commerical region?

Human will regulate their structure if they can't reproduce. In this case, I think the third sex will do this if it can't since this is a common characteristic for all living organisms.

Today, I read some function book. And I drew a lot of graph, but due to the size and my hand-drawing, the output is very ugly. I want to have a very good graph drawing software. Can you suggest some to me which are free, simple?

What does tension force mean? When we pull a box , left to us, with a rope, the force act is from left to right. So where does the normal force go? right to left?? if yes, how can we feel it?

No matter whether it can bring you happiness, but it must be legal. Which job bring you the largest amount of money?

I used latex. I have one more question. When a<g, the man does not float. This is because the acceleration just only reduce the effect of gravitational force from earth. When a=g, the effect of gravity is totally reduced. But when a>g, the man and the lift should fall into the same speed and same acceleration. 1.How come he can move upward in the lift and finally hit the ceiling if the acceleration continue to increase?This is when the calculation came negative.

What else does calculus consist besides function and limit ?

how to install latex, it needed to put many file inside. Would anyone upload the whole for me ?

yes I want it. I want to learn optics It is very interesting Under physics or biology is ok

Hello everyone, I am going to read some books in my summer holiday. Which region of mathematics involved in science the most? Or which part do you like the most? ( the most or most ???) Would you suggest to me?

Hello, I am here to seek for an answer for my question. In general, if a lift is disconnected with the rope, it falls with the acceleration about 9.8 m/s2. If a man is inside, he will fall at that acceleration too. I know that calculation [MATH] F_n = ma+mg [/MATH] That states that when a=g, the two objects cannot touch each other, so there are no normal force. 1. What is observed if a>g? It is known that the normal force and the apparent weight are negative, what does it mean? 2. What's the normal force? I do not totally understand this word. I think it's action-reaction force. The reaction force but I suspected why there are no movement by the objects. 3. What does the [MATH] \Sigma [/MATH] mean? 4. Is the net force not included the frictional force? Seek for every great answer

I want to question about what's vector linear mean? Why is temperature measured in a thermometer is a scalar measure?

The strange hydrogen atom leave the hydrogencarbonate ion, right? OR hydrogen atom bring the other ( one H + one O)and leave 1 carbon and 2 oxygen left?

how about subscript how to type it. It is very useful in chemistry area

I mean the sky with two part of colour at the same time. Is it strange?

Why does hydrogencarbonate based [MATH]H_2CO3 [/MATH] molecule give out carbon dioxide normally? Moreover, does H2CO3 carbonic acid give out carbon dioxide normally? It is hydrogen mixed with that ion.

anyway, thank you

I know it, and I'm not question about it. Sorry

thanks

What are your opinions and views on China or other countries like your own country? Talk here. I don't think foreign would go to the mainland deeply. The hygiene, safety has no "warrency". Also, the system practises communism and socialism but practise like totalitarianism and cause corruption. No people can talk about affairs of China loudly, even speaking. I'm very lucky to live in HK. It does not have this problem. Also, the freedom of commercial is also rank the first rather than the US (rank 2).

"'"When you install Windows Xp it dosnt let you use the user name "Linux""" Do you mean setting the administrator and guest name or others..?

At the early time in the morning, a part of the sky you notice is blue and a part of the sky is red in colour. Is that the red colour one is the west one or the east one? By the way, how do we determine the direction of the earth globe?