Primarygun

anyone build web site in your own computer?

What is the net force for a man (1kg)in a lift falling with a speed of 12m/s2? [MATH] \Sigma F_y=F_n-mg [/MATH]??? Is the gravitational force considered as external force?

I think the situation will not occur when the image seem to be on the horizontal.

yes I know it. But why do you use this method? Normally, don't we use the cross-method calculation only? If I don't say there has a trick or there are two possible answers, how many answers do you desire to get?

x+y=1 x=y Ya there are two answers. But what makes you know that x+y=1 is also possible. Normally, don't us only cancel the log sign to find out x=y instead of minus the left side by the right side and then fing x+y=1?

You mean highlight it in this forum?

solve for x in terms of y

Is the tension come from the reaction force right of the rope push the man's hand from right with pulling from right? And this make the rope straight?

oh I see. This acts like body in car. acceleration (+) make him behind

How about this one?

[MATH] log(x+y)/logx = log(x+y)/logy[/MATH] Can anybody show a calculation? I think that's a trick.

Why does the molecule or atom have potential energy? It doesn't have anything to attract.

how about the "Introductory of Chemistry"? That book with a lot of 3D molecules

Do there any kinetic energy and potential energy exist when there is only one atom or molecule in a bottle of vacuum?

Does the lift have weight while it's falling? Does it have the normal force? ( with air?)

Act like as a self-taught reading books. It is different from those lack of further study text books.

how about a software to plot graph for biology project? Beautiful one!

I am going to buy a very thick university books of science. Which subject should I buy? Biology, physics or chemistry? Which book do you have? Can you suggest some good books to me? Please lower than 35GBP

How to extract the graph into gif or bit?

So what are your occupation? And how much money do you earn???

ya sorry, I get confused because I was not very clear in concept with weight and normal force. Are they vector measure?Now I don't think so, right? I get troubled in the [MATH]mg[/MATH] because I always thought it was the weight and should act towards the earth. However, in the equation, it's the normal force, so act towards the sky and the [MATH]ma[/MATH] act towards the core, so the equation is correct in concept. However, one thing I am not very sure is the normal force. Why can scientist think a force which is present that in opposite direction as the [MATH]W[/MATH]?It seems it doesn't act like reaction force, but it does. Why? After I thought again, the highlighed words are wrong. The ma is the force that lift by the acceleration. That means when the lift fall with a=g, the normal force for him is the normal force for his actual weight minus the force by the acceleration. I think I am currently trap in the reference frames. I need to learn it shortly first When we pull a thing up, its normal force decreases. When we push a things down, its normal force increases. But, why it is reversed for the man in the lift? When the lift falls, the lift is like being pushing down. But, why its normal forces decreases? Why do the rope pull the lift make the lift heavier but make the man inside lighter?

ya f(x) Should be changed as y. Flash MX support drawing functional graph? hey, but why don't we need to enter the degree sign ? Calculator need to change to DEG first when calculate sin cos

can't use the f(x)=cosx What's wrong? How touse the degree sign?

What is International Student Edition (ISE) textbook? Are england's students entitled by this ? Also, referring to http://www.apbookshop.com/ What does ELT mean?

oh maybe I get some of it. Is it like when we sit in a car. Regardless the direction of y forces, when the car a=0, (no matter v is 1000 or 0 or others), we can sit inside safely and happily without the change in position. Oh, I got into a trap. Notice a but not v, I get why we are unchange in the car. But, I don't know why I can't bring this concept into the lift. Why do we stay at the middle part of the lift when a=g? I know the calculation, maybe still confused in the normal force. Why don't our body fall with the speed a=g? And thus, we won't leave the base of the lift. Can anyone tell me by concept?