Recent content by lalover

Ok, great. Thanks a lot.

So the original answer of 50 minutes is correct? And "precision of 1%" is just another way of saying the relative error is equal to .01? Thanks again.

Well our professor just gave us 1/sqrt(N), but I can see how it's equivalent to sqrt(N)/N. So you disagree with what davo789 said?

Well don't you have to convert the relative error by the amount measure to get absolute error? So would it be 0.01 times 1000? I'm not sure what the amount measured would be here.

Yeah I was thinking of using '.01' and setting it equal to 1/sqrt(N). If I did that, I got an answer of 50 minutes. Does that thinking seem reasonable? Thanks.

Homework Statement We want to measure the specific activity (number of decays per second) of a radioactive source so that we can use it to calibrate the equipment of the gamma-ray experiment. We use an electronic counter and a timer to measure the number of decays in a given time interval...

Ohh never mind I was misreading something. Sorry, no help is needed. Thanks.

Homework Statement My teacher posted this solution. It is exactly what I had, except I did not have 4Pi in the numerator. Rather, I had 2 instead of 4, and I didn't have Pi. The solution manual has had mistakes before, so I am wondering if that's what the case is here. Every other step, I had...

unfortunately my scanner sin't working properly right now and the assignment is due in an hour

That's just the definition for law of cosines. I don't know how to proceed from here though.

I think I am visualizing alpha and it's corresponding segments wrong.

would sin alpha be R/z ?

I thought the horizontal components canceled and I needed the vertical ones?

So would it be rcos(theta) that is added onto my integral instead of r-hat?

For the integration, I can pull sigma out because it's constant. That leaves me with... r-hat R^2 sin(theta')d(theta')d(phi') / R^2 +z^2 -2Rzcos(theta') My bounds for d(theta') are 0 to Pi and my bounds for d(phi') are 0 to 2Pi? Do I need to convert r-hat?