Recent content by Mathysics

1. Probability math help

1. Homework Statement A new drug is in trial, and it is found that the drug will cause adverse effects on some patient. 5% will have diarrhoea and 3% develop a rash after taking the drug. Also, 7% of patient have either diarrhoea, rash or both after taking the drug. Need to find the...
2. Whats the acceleration?

the following data apply to the speaker system: coil diameter = 5.8cm coil turns = 86 coil and cone mass = 30g magnetic flux density = 0.12T Current in the coil = 1.8A Using the above data, the acceleration of the cone will be? A) 12.6 b) 79.3 c) 113 d) 247 This comes from my revision sheet i...
3. Experiment and pu tiron nail into water

Re: rusting sorry my computer was having some problems... yes it changes from 2.36 to 2.6 in grams and are both measured in the same condition
4. Experiment and pu tiron nail into water

Re: rusting the cathode nail takes 25mins to gain 2.36 -> 2.4. This is not too accurate becuase there are those (green stuff?) form around the nail and when i pull the nail out and measure the weight those green stuff fall out and stay in solution. solution is HCl the rust on cathode...
5. Experiment and pu tiron nail into water

Re: rusting well yes when the nail form rust it is heavier but im not sure about the cathode (rusted iron) will gain or lose weight. I re-tested again at school day and still got the same result. So my question is how come the nail rust it gains weight, and when the nail being de-rusted it...
6. Experiment and pu tiron nail into water

Re: rusting well the h2o will have impurities, and the nail is actually steel and iron? As part of the experiment i am also to de rust the nail. would the nail suppose the gain weigh after electrolysis? Because when the nail rust it gains weigh, and if de rust will it lose weigh? but my nail...
7. Experiment and pu tiron nail into water

So i did an experiment and pu tiron nail into water and serveral days later it starts to rust. and i looked at the book and the chemical process is 1)Fe loses electron 2) that electron + oxygen + water produces hydroxide 3) hydroxide and Fe ion reacts and form Fe(OH)2, green rust 4)...
8. How charged particle got to do with magnetism

hello, I am not too sure of how charged particle got to do with magnetism. "Magnetism is a force of attraction or replusion that acts at a distance. It is due to a magnetic field, which is caused by moving electrically charged particles or is inherent in magnetic objects such as a magnet."...
9. Find the 50th derivative of the function

Re: [Urgent] Differentiation i know it now... is (-1)^n/2 x a^n cos ax (for even) thx for the help :)
10. Find the 50th derivative of the function

Re: [Urgent] Differentiation sorry it should be the 50th derivative
11. Find the 50th derivative of the function

1. Homework Statement Find the first, second, third, fourth, fifth derivatives of the function y = sin 3x. Find a rule that can help to find the 50th derivative of the function. It's urgent! 2. Homework Equations y= sin x y= cos x y' = cos x...
12. Polar form

1. Homework Statement solve below using de Moivre's theorem, in polar form z^3 = i 2. Homework Equations r CIS theta Answer:CIS pi/6, CIS 5pi/6, CIS (-pi/6) 3. The Attempt at a Solution r^3 = sqrt(0^2+1^2) r^3 = sqrt (1) r = sqrt (1) no idea how to get the angle
13. Frequency and penetration depth

ok thx that was very useful!
14. Frequency and penetration depth

why does the increase of sound frequency will decrease the penetration depth? how can this related to diffraction of sound?? Is it because they can be easily reflected?? need answer desperately, thx
15. Ultrasound machine

hey here is another question :S When the frequency of the wave is too high it will be absorbed easily? I don't understand why. Is it because of the increase in wavelength?