Here is the unit conversion if that is what your looking for.

________________

Hit me if I'm wrong, but...
You'd take the number of µsv in a CT scan and divide it by the number of µsv in an airplane flight.
An equation equation is something like
Number of µsv in a CT scan=Number of µsv in airplane flight X number of flights

saved me the trouble of having to convert.



And that's it, I just checked with a few friends and we ended up with the same answer. We are very good at making things 10xs harder than they really are.

Two friends and I have to build a cardboard boat that can carry at least two of us. We are trying to figure out the volume that the boat will have to displace to at least do it. The total mass of the both of us is 200 kg. How do we find the volume of water that we displace, and what are some recommended equations that we should use?

Last edited by Transdude1996 at 7:18 pm, Feb 3 2013

________________

Looks pretty comprehensive: Cardboard boat

isn't that 200kg of water?

Thank you. We kept on getting .2 m cubed as an answer, but we believed that it was wrong. Guess that we were right.

________________

do you mean the volume of the water you displace when boarding the boat?

the weight force is : F= m*g (this m is the total mass of you two and the boat)

the force F you get is epuivalent to the weight force of the water you displace.

so you use: m= F/g to get the weight of the displaced water.

with the density equation you get the volume

________________

That's what I said already. Thanks anyway.


Case Closed

________________

anyone know what mytho-poetic explanations are?

Edit: never mind (:

Last edited by neonkitty at 8:22 am, Mar 7 2013

Okay guys, this one is driving me nuts, and Google doesn't have any answers.

The problem is this

arccos(5)=x, which is the same as saying cos(x)=5. What is the value of x? I know it is supposed to be a complex number.

I can get as far as to say 10=e^(ix) + e^(-ix), but I don't remember what to do from here.... any takers?

for those wondering how I got to that,
e^(ix) = cos(x) + isin(x)
e^(-ix) = cos(x) - isin(x)

cos(x) = (e^(ix) + e^(-ix)) / 2

________________
"This year, they should give the Nobel Peace Prize to the inventors of cancer and accidents, because research shows those are the main causes of disarmament."

arccos can be defined in terms of the complex logarithm to be arccos(x) = -i*ln(x + i*sqrt{1-x^2})

I think. You should go through the proof yourself.

theta = arccos(x)
e^(i*theta) = cos(theta) + i*sin(theta) = cos(arccos(x)) + i*sin(arccos(x))
= x + i*sqrt(1-x^2)

so: ln(e^i*theta) = i*theta = ln(x + i*sqrt(1-x^2))

FINAL ANSWER: arccos(5) = -i * ln(5-sqrt(24)) ~= 2.29 i

edit: checked in matlab, this is a correct answer. the general solution is x = -i * ln(5-sqrt(24)) + 2*n*pi because, of course, cosine is periodic (even in the complex plane)

Last edited by Ashen-Shugar at 3:52 pm, Sep 12 2013

Thank you. Also, your proof is quite nice. Now I don't have to go mad.

________________
"This year, they should give the Nobel Peace Prize to the inventors of cancer and accidents, because research shows those are the main causes of disarmament."

Urgent help! I am in first year in my undergraduate course and we are having C programming. Sadly tomorrow is exam! We are at very basic level so it's going to be easy or so I hope.

Could anyone please write a c code for the foll. question? I know how to find the average but how to find the best of two? Please write the program using stdio.h only... i mean no help of conio or some special functions as we haven't stsrted them.

Question: C-program to accept three test marks from user and print the average of best of two.

I would be greatful if you can provide the answer in few hours as we are having exam after 13 hours! T_T Thanks.

________________

May not be exact C syntax since I didn't throw it into a compiler

The key is that it's harder to find the highest 2 of 3 than the lowest 1 of 3 (difference of finding 2 things vs 1 thing). But the two are actually equivalent in meaning for this question. Trying to find the former would involve more nested if/else statements


int averageofbestoftwo (double a, double b, double c)
{
double result = 0;

//find lowest number

//if a is lowest
if (a < b && a < c)
{
//then average b and c
result = (b + c) / 2;
}
//if b is lowest
else if (b < a && b < c)
{
//then average a and c
result = (a + c) / 2;
}
//then c is lowest
else
{
//then average a and b
result = (a + b) / 2;
}

return result;
}

________________
A just ruler amongst tyrants