Monday
February 8, 2016

Posts by bobpursley

Total # Posts: 39,488

Physics
hf=hi+vi*t-4.8t^2 0=0+10*t-4.8t^2 solve for t. Max height, solve for hf at time half the above time.
February 8, 2016

Physics
well, time up is the same as time down, the max height can be found at time .43/2. hf=hi+vi*t-4.8t^2
February 8, 2016

Chemistry
You wont get much help with just that info. What is the problem.
February 8, 2016

Biology
In your text, under the section "Evidences from embrology", it lists them for you. Modern Biology. Grab your book and read.
February 7, 2016

Physics
I dont see how this can be done without some crazy assumptions about energy lost. On the sliding, you have zero friction (no energy lost), but the block itself. Is one to assume no energy is lost in the block internally as a bullet goes thru it? It can be worked with that ...
February 7, 2016

Physics
mgh-energylostslidingpole =final energy mg(5.8)-263*5.8=1/2 m vf^2 solve for vf I dont see any connection with the mass of the platform, or spring holding it up.
February 7, 2016

academy
The force above the water is zero. The force below the water is equal to the weight of water above that point. Because the weight is is linear dependent on depth, we can average it. So from the bottom, up .75*50cm, the average pressure in the water area is densitywater*.75*...
February 7, 2016

Chemistry
Assuming plenty of oxygen, then for each mole of propane, one will get 4 moles of water vapor. Figure the moles of H2O, convert that to mass. Your teacher is just too easy.
February 7, 2016

physics
Vf^2=vi^2 + 2ad solve for acceleration a. Then, remember Force=m*a ? solve for force.
February 7, 2016

physics
The law of conservation of momentum applies mV+0=(M+m)V' solve for V
February 7, 2016

Calculus
integrate? http://mathworld.wolfram.com/TriangleArea.html
February 6, 2016

physics
Do you know calculus? a) take the first derivative of position to get velocity. p(t)=6.60 i − 9.00t^2 j v(t)=0i -18t j b. velocity given above, so acceleration is dv/dt or a(t)=-18 j c. put in t=5 and calculate.
February 6, 2016

Algebra
area=LW L-60=W 1600=(W+60)W multiply it out, and solve for W
February 6, 2016

Physics
wonderful.
February 6, 2016

Help please? Math 141 (Pre-Cal) (Shapes)
it would be nice to know how much derivative calculus you know. a) area=LW Perimter=180=2L+2W or W=90-L Area=L(90-L)=90L-L^2 Ok: non calculus approach. That equation is a parabola, with roots at L=0, or L=90. So the max must be halfway, or L=45. Then W=45. Max area=45^2 Now ...
February 5, 2016

Chemistry
unbalanced? the first one.
February 5, 2016

Physics
PE= -Eqd=61OO V/m * 12E-6C*.05, so the energy is reduced. Electric field potential is defined as the negative of the work done by the electric field moving a charge in an electric field.
February 5, 2016

Science
yes, those are ok, but I would have included atmospheric pressure, visibility, pollen count, water vapor content.
February 5, 2016

Chemistry
from M2O3, valence is +3 Now M2O3 converts to two moles of MCl3. M2O3 + Cl2 >> 2MCl3 + ??? so 11.205 grams of M2O3 is x moles, and 15.380g of MCl3 is 2x moles. mole mass MCl3= M + 3*35=M+105 mole mass M2O3= 2M+3*16=2M+48 moles of MCl3=15.380/(M+105)=2x mass of M in M2O3=...
February 5, 2016

Physics
What is y, what is x? How is this related to g?
February 5, 2016

SS HELP NOW PLZZ
Have you thought of transportation and labour supply as necessary, as is nearby markets to sell goods? Coal (and wood) can supply energy, certainly. Factories need energy. Why? Why is water needed? Hint: what transports goods across the ocean? Why would a labor supply be ...
February 5, 2016

i really need help and i dont ask alot so plzz
You are headed that way again. Are you wishing for a magic wand? I have never found one in real life. Take these questions one by one, and figure them out one by one. Waiting for inspiration for all the answers is just a waste of time. I will be happy to check your work and ...
February 5, 2016

Physics
distanceUP/145m= tangent(4.5deg) solve for distance higher
February 5, 2016

physics
hf=hi+vi'*t-4.9t^2 solve for hi, hf=o, vi=15sin35, t=2.7
February 5, 2016

Math
correct.
February 5, 2016

Math
a "regular quadrilateral" usually menas all sides are equal, and it does not have to be square. is sides are 20ft, perimeter has to be four times one side.
February 5, 2016

pysics
a) how long does it take something to fall 25m? hf=hi+vi*t-4.9t^2 hf=0, hi=25, vi=0 (vertical velocity), solve for time t. speed: v=sqrt(vhorital^2+vf'^2) where vf'=final vertical speed = -9.8*timefalling angle, measured from the horizontal, = arc (vf'/vh)
February 5, 2016

Physics
a) hookes law b) c) isn't this simple harmonic motion, and there are standard formulas for this?
February 5, 2016

physics
vertical component. hf=hi+vi'*t-4.9t^2 hf=0, vi'=-7.5sin18, t=5, solve for hi horizontal distance: distance=vi*cos18*timeinair for the c), same formula as above, solve for t given hf=-10
February 5, 2016

algebra 1
11=Q+D 10D+25Q=200 solve for Q, and D, I assume you can do that by substitution.
February 5, 2016

physics
looking at your posts, are you taking a test? cheating?
February 5, 2016

physics
I will be happy to critique your work.
February 5, 2016

general chemistry
I agree, you are not doing it right. Look at the units: mass, you have chosen volume ml. Density=13g/ml you can do it more precise volume=345 ml basic definition Density=mass/volume so mass= density*volume mass= 13g/ml*345ml= xxxx grams
February 5, 2016

Social studies
I dont know the factors of those areas, but I do know farming. Farming is best in a) fertile soil b) ample, reliable water (preferable rain) c) access to markets d) safe area from thieves, predators, and vandals e) good safe area to raise a family in f) land prices are ...
February 5, 2016

Calculus
Something is missing in this problem statement. Why can't he stand anywhere and see the clock?
February 5, 2016

English
a) it is a woman's job b) boys are distracted easily and might hurt themselves c) boys have better things to do d) they can't understand the importance of cleanliness e) They never wash their hands f) we dont want to have them around girls g) They don't think ahead...
February 5, 2016

chemistry
The most accurage way is to mass the tube on a balance. The other way is to form a committee and guess.
February 5, 2016

Physics
This is a vector problem. You are adding two velocities at 90 degrees. distance across 1.29miles distance north=2.58m/s*timeinwater time across: 1.29/speedofboat now I notice the 1.29 is in miles, the 15 in miles /hour. Convert all to meters per second. Solve for time across. ...
February 4, 2016

Physics
force=mass*v^2/r 10=.005*14^2/r r=you do it. r will be in meters.
February 4, 2016

Physics
Well, for one, they are already friends... Force=G*55*60/2.4^2 knowing G, that is very little force.
February 4, 2016

Physics
speed=sqrt(1.54^2 + 11.2^2) direction: arctan(11.2/1.54) relative to shore
February 4, 2016

chem
matter in the reactants just rearrange themselves into products, it is the same total matter.
February 4, 2016

Chemistry
selective precipitation (solubility)
February 4, 2016

science
KE is dependent on the square of the velocity. twice^2 = 4times
February 4, 2016

farm disease
black leg BRUCELLOSIS google each of those. You will find all you ever wanted on the internet.
February 4, 2016

genetics
It has been taught to millions of high school students that it is two genes, nowadays, a few teachers (I hope yours) is teaching that eye color is much more complicated, and two genes are required: http://genetics.thetech.org/sites/default/files/EyeColorChart2.gif the man ...
February 4, 2016

Math
a^3b(3-7+10)+a^2b(4-5)+2ab check me.
February 4, 2016

Chemistry
a. add water, dissolve the solid sodium hydroxide. Caution, much heat is created, and can catch thing on fire. b. Melt it. This probably is just a bit unsafe to do in an ordinary chem lab, the melting point is very high, and the NaOH can (and will) react with atmospheric gases...
February 4, 2016

geometry
Inside the circle? Anywhere? I have no idea.
February 4, 2016

chemistry
FeO is iron(II)oxide. You get it by heating Fe in air (O2)
February 4, 2016

Calculus
Study this http://www.math-cs.gordon.edu/~kcrisman/math0001/math152/hmkhelp.pdf
February 4, 2016

science help PLS
One can conclude that the star is very bright. It usually also means large, but that is not always true on bright stars. However, of the choices, A is probably the best choice, but I suspect many astrophysicists would want to bite their tongue on such a simple answer, without ...
February 4, 2016

Geometry
d^2=(5-4)^2+(-6+4)^2+(o,6)^2 = 1+4+36=41
February 4, 2016

physics
wf=wi+alpha*t but alpha (acceleration)=force/I so solve for time t. 2PI*0=2PI*50-.5/2E-2 * t
February 4, 2016

physics
sketch this on a force vector triangle. Be certain to do the 200N and P head to tail, and recompute the angle between (it is not 200) the head and tail of the other. Now use the law of sines.
February 4, 2016

physics
see other post.
February 4, 2016

physics help
see other post.
February 4, 2016

Maths
1 liter=1000cm^3 volume=PI*r^2 *h 1000=PI*25*h solve for h in cm.
February 4, 2016

Chemistry
Lord no. You need to be specific on which enzyme. Some prefer slightly acidic, some neutral, some slightly basic, however non in the range 8-14 that I know of
February 4, 2016

Maths
what is 12 inches in ounces? Newton meter= work lbs/in^2=pressure inches=linear measurement ounces=weight You have to compare like to like units, at least here in Texas.
February 4, 2016

prealgebra
3000=2500(1.04)^t assuming annual interest compounded. Take log of each side log3000=log2500 + t log (1.04) solve for t.
February 4, 2016

Chemistry
Wondering what the reaction that does this...it matters.
February 4, 2016

Calculus
What does "thrown up 6 feet from the ground(it is released 18 feet above the ground)" mean.
February 4, 2016

Physics
a. The easy way, if you know trig, is to draw the vectors head to tail, and draw the resultant. Then label all the angles, and figure the interiour angles. then magnitude of the resultant is found by law of cosines, and direction by law of sines.
February 4, 2016

science
force; weight; attraction; Think about this. Step on a scale. record the "force". So the Earth is attracting you with that force. But, you are attracting the EArth with the same force.
February 4, 2016

physics
the sum of heats gained is zero. 20*c*(Tf-60)+60c(Tf-20)=0 solve for Tf
February 4, 2016

need some math help
what is .35*20?
February 3, 2016

math help
see other post.
February 3, 2016

Math HELP
f(1.5)=3(1.5)-2
February 3, 2016

Maths
distance formula comes to the rescue: 10^2=(x+2)^2+(4+2)^2 solve for x.
February 3, 2016

algebra
log3(27)+log3(x) 3+log3(x)
February 3, 2016

Physics
and is there a question here?
February 3, 2016

Geography
This is not a play area. Want to be locked out? keep it up. We are here to help kids, not entertain the subnormals.
February 3, 2016

chemistry
on temp, pressue, assume they do not change. I think you are off track, this is not a gas law problem. it takes 5 volumes of O2 to react with 2 volumes C2H2. volumeO2=5/2 * 89.2Liters Law: You need to read the Law of combining volumes: https://en.wikipedia.org/wiki/Gay%E2%80%...
February 3, 2016

chemistry
The reaction will tend to the right.
February 3, 2016

physic
I will be happy to critique your work.
February 3, 2016

Physics
a. weight=mg-mv^2/r b. set weight to zero, and solve for v. c. weight=mg+mv^2/r
February 3, 2016

physics
I will be happy to critique your work.
February 3, 2016

Physics
see other post.
February 2, 2016

Physics
https://www.youtube.com/watch?v=OrryaQqcvk8
February 2, 2016

Geography
I agree.
February 2, 2016

Math (calculus )
shouldn't the function really be v(t) =C-t ([c-s]/n) ?
February 2, 2016

Math
correct
February 2, 2016

Teenagers
opinions cannot be facts. facts are statements that can be verified or refuted by observation of many people. Opinions can never be verified. An opinion is what someone thinks, and others cannot refute or verify that. If you had wanted to make the statement factual, then.. <...
February 2, 2016

Persuasion Essay
see my previous post on this.
February 2, 2016

social studies (again)
Montesquieu is thinking that people can be herded to vote in certain ways by folks who lie, cheat, and steal from them, or corrupt them with ideas that sound great but are ridiculously unworkable. Rousseau seemed to think folks had to be held accountable for protecting their ...
February 2, 2016

AP Chemistry
The answers are really lousy, but I suspect your teacher wants you to raise your hand and answer D.
February 2, 2016

Definition
DUH. I gave you the answer.
February 2, 2016

Persuasion Presentation
Persuasion based on Harry Potter, which is fiction? I guess that is ok, I listened to several folks running for President in IOWA who were trying to persuade citizens to vote for them because of factitious arguments and facts, most of them around religion, immigrants, emails, ...
February 2, 2016

Science
Pure substance is a set ratio of atoms that cannot be separated by physical means.
February 2, 2016

Science
Consider the law of conservation of momentum. If she can give the tool belt momentum GREATER than her momentum, in the opposite direction, she might make it back.
February 2, 2016

physics
tension max=mg from the hanging mass centripetla force=mw^2*r tensionmax=mr*w^2 mg=mr*w^2 w=sqrt(g/r) radians per second.
February 2, 2016

algebra
5P+4M= 1.75 8P+5M=2.45
February 2, 2016

SO HARD! MATH
Darn, it is time to grow up. Already.
February 2, 2016

Physics
PE=2*9.8*heightinMeters joules KE=1/2 *2*v^2 but v^2=vi^2+2 g* (5-h) so KE= gh total energy=PE+KE=2*9.8*h+2*9.8*(5-h) = 2*9.8*5 joules so it starts our at h=5 with all PE, then that energy changes to KE as it falls. At the bottom, it is converted to heat, sound. =
February 2, 2016

physics
vf^2=vi^2+2ad 5000^2=0+2a*4 a=5000^2/8 for time: vf=at solve for time t.
February 1, 2016

Physical science
current=voltage/resistance=9/20 amps
February 1, 2016

Science
350N
February 1, 2016

Math - Another question to check, sorry... =/
go to the head of our class, correct.
February 1, 2016

math
as a fraction, it is simplified.
February 1, 2016

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