Recent content by erok81

Ooooh yes. I see now. That is very straightforward. :) Now I have: 2 ≤ v ≤ 3 0 ≤ u ≤ 1 I am guessing you choose which for v and which for u based on plotting the graph and seeing which corresponds to which axis? I tried swapping them and it wasn't working so well (I got results with x...

Okay, this should be right. I have x=(3u-v)/5 and y=(2v-u)/5 But I think I am doing something wrong as this is just getting messier and messier the further I go. Using the first boundary y=-(x/3)+1 and my two equations there I end up with v=(5-2u)/3. Which I am pretty sure is wrong because...

Homework Statement Integrate the following over the set E. \int_E \frac{2x+y}{x+3y} dA Bounded by the lines: y = −x/3+1 y = −x/3+2/3 y = −2x y = −2x + 1 Homework Equations None. The Attempt at a Solution I can up to the same point everytime, but always get stuck on finding the new...

I am assuming I can't take the inverse of that thing like I did? Would the more appropriate solution to cross multiply everything to get r alone?

Homework Statement There is a charge Q=1 μC located at x=0 and a charge -Q/2 located at x=4 m. What is the E-field. At what value of x is the E-field zero? Express your answer in meters and do not approximate decimals digits. Homework Equations E=\frac{q_1 q_2 k_c}{r^2} Removing...

Hmm...I'm not sure that it depends on temp. Rspec=R/M where R is gas constant and M is molar mass. With that said, I don't see how it can vary with temp.

Homework Statement I have a balloon with a volume of 500m3 Outside air temp of 300K Mass to lift of 300kg Molar mass of air is 28 g/mol (I didn't end up using this) I am to find the temperature inside the balloon to barely lift the given mass. I have apparently forgotten everything...

Homework Statement In a previous problem I had to find the entropy of a black hole where I ended with this: S_{BH}=\frac{8 \pi^2 G M^2 k}{h c} Now I am to find the temp, given the energy of a black hole is mc2. Homework Equations T=(\frac{\partial S}{\partial u})^{-1} The...

Thanks for the help. :)

Ooooh. I see where you are headed now! It starts at -15C. So I need to figure how much heat it's taking from -15 to zero, the latent heat part from freezing to non freezing, then 0C up to 65C it's final temperature. And look at that; I just happen to have three stages just like you...

If I am understanding correctly (which I don't think I am)... For melting ice 80 cal/g For boiling water 540 cal/g I don't have work for those as they are given in the text. Which is just the latent heat formula L=Q/m I'm not sure on the three stages you mentioned. The ice will only go from...

The ice ends up at the same final temp as the tea, so 65. And it will go from solid to a liquid. I tried throwing in the latent heat (H) for melting ice at 80 cal/g but it didn't work out correctly.

Homework Statement Your 200-g cup of tea is boiling-hot. About how much ice should your add to bring it down to a comfortable sipping temperature of65°C . Assume that the ice is initially at−15°C . The specific heat capacity of ice is 0.5cal g⋅°C , for water is 1 cal g⋅°C. The latent...

So in this case ΔT isn't necessarily Tf-Ti like most Δ's. It's more for interpretation...if that makes sense. I get what you are saying. For this problems the final and initial are "swapped" since the water has to lose heat at the end. If I do final - initial, the ΔT is negative and...

However if I swap the temp values like an example I saw... cwmw(Twi-Tf)=cpmp(Tf-Tpi) After the algebra I end up with... T_f = \frac{(c_p m_p T_{pi}) + (c_w m_w T_{wi})}{(c_w m_w) + (c_p m_p)} I get 85.125C. Which is a lot more reasonable. If that's the case, why do the temps...