Homework Help

I saw this question on my study guide and I have NO idea what they are asking or what they want. Can someone point out to me what they want and how I can go about doing that?

Hi all, i am just having a little bit of a problem with part © of this question.... i get [math] \frac{dr}{dt} = r^3 [/math] and so [math] r(t) = -\frac{1}{\sqrt{2t}} [/math] this doesnt seem right to me....but what do i know! also i can't see how to get [math] \frac{d \theta}{dt} [/math] any ideas guys? Thanks Sarah

hey, sorry for all the questions lately but .... for this is question, is the only critical point (1,0) ? it keeps refering to critical pointS in the problem... but i think there is the only the one critical point, right? as for the rest of the question, well i suppose i need to figure this little kenumdrem (spelling? ) out first, hey thanks, and apologies for the questions again! -Sarah

hey all damn this problem, i have spent hours at it and keep ending up in a big mess... any ideas guys? :S Sarah

If an engine must do 500 joules of work to pull a 10 kg load up to a heaight of 4 meters, what is the efficiency of the engine? I got 8%. Am I correct?

1. The distance between two wave crests in the water is 3 meters. A swimmer notices one wave goes by every six seconds. What is the speed of the wave. 2. There is a delay of 5 seconds between the time you see a flash of lightning and hear the thunder. If the temperature is 20 degrees C, how far away is the lightning strike. I haven't a clue where to start on either of these.

hey everyone hmm...can't seem to work out how to attack this question.... any suggestions guys? Cheers Sarah

Hi all, i have done this question which involves capillary waves. where we started with [math] \lambda \propto \lambda^{-3/2} [/math] then i found that [math] v_{phase} = \frac{\lambda^{-1/2}}{2\pi} [/math] and [math] v_{group} = \frac{3\lambda^{-1/2}}{4\pi} [/math] and thus taking the ratio of the two gives that the group velocity is 1.5 times the the phase velocity. I am them asked to explain the meaning of this result, and i am a little unsure of how to answer that.... any ideas/hints etc.? Cheers Sarah

Hi, I need help with this question what is the molar concentration of 0.50 mol of NaCl dissolved in 0.30L of solution? =moles of solute/leters of solution =0.50mol/0.30L =1.7 mol/L Is this correct? and what mass of solute is present in 1.00L of 0.045 mol/L of Ca(oH)2, solution I have no idea how to do this one

Hi, I really need help with this question 1) the water depth in a harber is 21m at hight tide, and 11m at low tide. One cycle is completed approximatly every 12h. a) find an equation for the water depth as a function of the time, t hours, after low tide b) Draw a graph 48h after low tide, witch occured at 14:00 y=asink(x-c)+d Amplitude a=21-11/2 a=5 K p=2pi/k 12=2pi/k k=2pi/12 k=pi/6 what about the c and the d?? and does anyone know of anygood software to graph trig functions? Thanks

the folowing reaction proceeds with a 70% yeild C6H6 + HNO3 = C6H5NO2 + H2O calculate the mass of C6H5NO2 expected if 12.8g of C6H5 reacts with excess HNO3 How do you do this problem? and If 3.45 x 10^23 formula units of Hg(NO3)2 are reacted with excess of Na2S, what mass of HgS can be expected if this process occurs with 97% yield? What are fomula units?

Spider or lizard? Why?

Hi, I'm having trouble answering this question. I don't know how to start. Any help is greatly appreciated Thanks. Using the data below for CCl4, calculate the total energy required to heat 1.24 mol of CCl4 from -43°C to 109°C. Cp(s) = Cp(l) = 132 JK-1mol-1, Cp(g) = 83 JK-1mol-1 Cp: molar heat capacity melting point = -23°C, boiling point = 77°C Hm (melting) = 2.50 kJmol-1, Hv (Heat vaporisation)= 33.0 kJmol-1 A) 23.0 J B) 67.0 kJ C) 60.3 kJ D) 56.9 kJ E) 22.9 kJ

Solve each equation by completing the square: 3x^2+x-2=0 Find the exact solution to 2x^2=9x-5 by using the Quasratic Formula. Find the value of the discriminant for each quadratic equation. Then describe the number and type of roots for the equation. 25x^2-20x+4=0 2x^2+10x+9=2x Write an equation for the parabola with vertex at (-4,2) and y-intercept -2. Solve 2x^2-7x-15<0 algebraically. Solve 3x^2-x=4 by factoring.

i have been given this question as part of a maths assignment so i dont want to be put into a situation where i might be advantaged against my other classmates with too much extra help but i was wondering if anyone could help me define y in this, im pretty confident that i have the right answer. i just cant think of the words to define it. A motorist covered the first third of the distance at 60km/hr and the next third at 90km/hr. If the average speed for the whole trip was 80km/hr, what was the speed for the final third of the trip? Here is my answer: [math] \frac{y}{3} [/math] =80 y= 240 60+90+x=240 150+x=240 x=90 the speed…

Hey everyone i have done all this problem, except the "hence" bit. i just can't quite get it... could anyone please give me a hint Thanks Sarah

Charles Darwin discovered flightless cormorants on the Galapagos islands. How might the discovery of this unusual bird have influenced his thinking about evolution?? I'll ask more when this one is answered....

my physics homework is to memorize the periodic table (including all the symbols) and in groups. Is there an easier way to do this?

Sum and Product of Roots!!! Find the quadratic equation that has the given roots: 1: 3/4, 9/2 2: -0.25, o.25 HELP ME!!!

Hi see the attached picture... 2 coupled masses, each suspended from spring in gravitational field... also entire construction can vibrate only vertically... I need to write lagrangian for this system in the following form: [math] L = \frac{1}{2}\sum_{i=1,j=1}^{2}m_{ij}\dot{x}_i\dot{x}_j-\frac{1}{2}\sum_{i=1,j=1}^{2}k_{ij}x_ix_j [/math] [math]x_i[/math] and [math]x_j[/math] are displacements of masses from equalibrium positions and springs are identical the kinetic part of L is easy one but i stack with potential part... i get to this expression(i always confused about right signs): [math]m_1g(l+x_1)+m_2g(l+x_1+l+x_2) + \frac{1}{2}m_1{x_1}…

When a magnetised wire of magnetic moment M is bend in form of semicircle,what will be its new magnetic moment?

do you guys have any idea of what could have formed this river or which river it is? it is somewhere between chicago and las vegas..........

[math] \int{(32-x^{5})^{(.2)}dx} [/math] How do you do that and what integration method(s) did you use?

Hi, I came across these questions when I was revising my chemistry studies. If you guys could help me out? 1. It says "......polyatomic ions. These ions, which act as discrete units, are positively or negatively charged combinations of two or more atoms." What does 'discrete units' actually mean in this situation? 2. What is the difference between inorganic compounds and organic compounds? Why are they seperated? 3. What is absolute zero? Thanks

There is a circle with the radius r around the centre O, there is a minor sector with a perimiter of 100cm and an area of Acm2, show that the area of the sector is A=50r-r2 I figured that as [math]P=2r+\theta^{c} r=100[/math] I should find some way of fitting that in the same equation as [math]A=\frac{1}{2}r^{2}\theta^{c}[/math], but I couldn't do that without getting a useless mess. Any help? edit: could some mod take out the dual post please?