Wednesday
July 30, 2014

Posts by Damon


Total # Posts: 17,557

Physics
call 41.18 41.2 maybe, sometimes they fuss about their round off rules.

Physics
Well, it is their word against mine I guess, but check my arithmetic and units carefully Physics - Damon, Sunday, March 30, 2014 at 7:21pm 25 L = 25 * 10^-3 m^3 2.77 cm = .0277 m 1.4 min = 84 seconds flow rate * time = amount pi r^2 v * 84 = .025 m^3 pi (.0139)^2 v = .025 v = ...

Steve, Reiny ??
I did this twice and do not see errors. Did I make some stupid mistake?

Physics
Well, figure out what I did wrong. (I think nothing)

This is getting tiresome
I answered this. Also the other one about circumferences several times.

Math
1/2 if a length dimension on the big one is twice the same length dimension on the little one then lengths on the small one are 1/2 those on the big one.

Math
4 * 50

Math
4 n - 6 = 2 n + 4 2 n = 10 n =5

math
22.5 quarts = .75 (total) total = 22.5/.75 we have .25 * total so we have .25 * 22.5/.75 =22.5/3 = 7.5

Physics
25 L = 25 * 10^-3 m^3 2.77 cm = .0277 m 1.4 min = 84 seconds flow rate * time = amount pi r^2 v * 84 = .025 m^3 pi (.0139)^2 v = .025 v = 41.18 m/s if 1/3 diameter then 1/9 of area so speed is nine times original 371 m/s

Physic
http://www.jiskha.com/display.cgi?id=1396215852

Physic
I did my best earlier.

Calculus Help Please!!!
LOL - Guess which of us is the mathematician and which is the Engineer :)

Calculus Help Please!!!
Q = incoming flow rate = .1 m^3/min dh/ dt = Q A where A = surface area = length * width at 20 cm depth which depth is (1/2) height width = 30 + 1/2(70-30) = 30+20 = 50 cm = .5 m wide water surface so A = 5 * .50 =2.5 m^3 so finally dh/dt = .1 * 2.5 = .25 m/min = 25 cm/min

Physics
vertical ? I thought table was level. I will assume you mean from the y axis. final momentum y component = m (5) cos 28 + m (4) cos 32 = 7.81 m final momentum x component (I will assume one + and the other -) = m (5) sin 28 - m(4) sin 32 = 2.18 m Now I will have to assume some...

Physics
inelastic, energy was radiated in sound waves

Physics
If Vector A + Vector B = Vector C then orthogonal components of the vectors also add. If V = A + B then Vx = Ax + Bx and Vy = Ay + By and Vz = Az + Bz and as many more dimensions as our tensor occupies ") (b) NO !!!!! It is only conserved in an elastic collision Energy is...

algreba
In both cases just add the two equations

My typo
" Libel is viewed differently in United Staes and Japanese law and is far more difficult to establish in a United States court. "

Proofreading..Jrn Law
Should it not say in an introductory sentence that you are talking about libel? Such as: " Libel is viewed differently in United Staes and Japanese law and is far more difficult to establish in a Japanese court. " win THE case or HIS OR HER case (singular or say &quo...

physic
Use the same argument but same voltage on each

physic
In series the charge has to be the same on both, call it Q by definition each capacitance C= Q/V so Veach = Q/C now in series the voltages on each capacitor add so V total = 2 Q/C but by definition our equivalent capacitance = Q/Vtotal = C/2

whoops
Use Steve's answer

math
makes good 2 miles per day after 12 day/night cycles is at the 24 mile mark so he will just make it at dusk on the 25 th day

physics
BUT they want miles/ hr so 29.4 m/s * 1 mile/1609 m * 3600 s/h = 65.8 miles/hour

physics
the ground is 3 seconds down d = (1/2) (9.81) (3)^2 correct d = 44.1 METERS (THAT IS PART B) (that is 9.81 m/s^2 * 9 s^2 so just m or meters) NOW THE SPEED (Part A) v = g t v = 9.81 m/s^2 * 3 s = 29.4 m/s (THAT IS PART A)

physics
You are terrribly fouled up with units. Give me a minute

physics
WORK IN METRIC convert later if dealing with carpenters.

physics
come on now, use what we have done v = g t but to go from m/s to mi/hr use 3600 seconds / hour and 1609 meters/mile a floor is about 3 meters

Math
2 = 1.0275^n log 2 = n log 1.0275 n = 25.6 years

statistics
Binomial distribution find probability of zero boys P(0) answer is 1 - P(0) n = 6 p = .5 and 1-p = .5 P(0) = C(6,0) (.5)^0 (.5^6) coef for any n,0 = 1 so P(0) = .5^6 = .0156 1-P(0) = .984

Math 110 UOP
Multiply 28x72 using lattice method. been there done that, see below and please post once HUH, 5^2 = 4^2 +3^2 if that is what you mean

Math 110
278 = 2*139 139 is a prime number to that is the end ***** 2 ***** 8 **** 1->2 1/4 **** 5/6 ** 7 9->0 0/4 **** 1/6 ** 2 11->1 *** 6 so 2016

physics
What speed does the ball in the first question have in falling 3.5 s? ------------------- I told you in the first line, 34.3 m/s ------------------- in 4 sec d = .5 * 9.81 *16 = 78.5 meters so no

physics
v = g t = 9.81 * 3.5 = 34.3 m/s but what if it hit the ground? d = (1/2) g t^2 = 60 meters so it has not hit ground yet, whew

Physics
area = A = pi D^2/4 = pi (.0277^2)/4 = 6.03*10^-4 m^2 Q = volume/second 25 * 10^-3 m^3 / 84 s = .298 *10^-3 m^3/s A v = Q v = Q/A = .298*10^-3/6.03*10^-4 = .0494 *10^1 = .494 m/s

physics
a = change in velocity/change in time = 44/5 = 8.8 ft/s^2 a = same formula = (88-44)/4 = 11 ft/s^2 a = (66 -88)/3 = -7.33 ft/s^2 sum of a*t / total t (8.8*5 + 11*4 - 7.33*3)/12 = 5.5 m/s^2

physics
5/20=4 km/min = 4,000 m/min = 66.67 m/s? BECAUSE 5/20 = 1/4 not 4

physics
5000 meters in 20*60 = 1200 seconds Vi = 30,000 m / 3600 s = 83.3 m/s v = Vi + a t 0 = 83.3 + a (1200) a = - .0694 = - 6.94 * 10^-2 m/s^2 average velocity with constant acceleration = (first + last)/2 = 83.3/2 = 41.7 m/s

physics
750 m/ 20 s 1500 m / 45 s

college algebra
2 x 10to the what? and 3.5 times ten to the what ?

US government
Well, presidents seem to start wars without much voting in Congress these days :)

US government
Well, I guess our first choices are consistent :)

US government
the government the citizens among many other possible answers such as: money, health military, poor capital , labor federal government , states

Math
a = .5 r = .5 a r^(n-1) = .5 * .5(6) = .0078125 That is maybe a pepper corn :) http://www.mathsisfun.com/algebra/sequences-sums-geometric.html

math
Yes, I wondered about this state's educational achievements as well :)

math
.56 (11) = 6.16 I have no idea what the standard deviation is so can not do more. If I knew it I would use mean of 6.16 and some standard deviation in: http://davidmlane.com/hyperstat/z_table.html

Physics
The force from the car on the truck = 4420 - 1230 a So our task is to find a total m = 1230 + 2180 = 3410 kg total F = 4420 - 750 = 3670 N so a = 3670/3410 = 1.08 m/s^2 so finally F on truck = 4420 - 1230 (1.08) F on truck = 3096 Newtons

calcules
change in percent bought is only half the percent change in price

calcules
Q = 342.5 / P^.5314 dQ/dP = -342.5 (.5314) P^-.4686/ P^1.063 so dQ/dP = - 182 P^-1.5316 well, we need to know what P is at the intersection P = q P^1.5314 = 342.5 1.5314 log P = 2.535 log P = 1.655 P = 45.2 so dQ/dP at intersection = -182(45.2)^-1.5316 = .531

probability
Steve answered this above.

physics
The electric company is supplying energy to the room and it is heating up. We hope she is using a CFL or LED lamp to minimize heating of the room and waste of energy.

3 science questions
7. Which of the following is used to make biomass fuel? B. plants and animal waste C. coal <----- ============================ NO !!!!!!!!!! plants and animal waste!! bio mass means made out of present biological materials, not dinosaurs. ----------------------- 11. Solar, ...

physic
change in rpm = 170 170 rev/min *1 min/60 s * 2 pi radians/rev = 17.8 radians/second change which is delta omega alpha = change in omega/ change in time -17.8 radians/second / 4.4 seconds = 4.05 radians/second^2

no figure
You can not copy and paste here so I can not see the geometry.

Physic Angular momentum and torque
r = 0.19 m I =.5 m r^2 =.5 (1)(.19)^2 = .0181 kg m^2 1700 rev/min * 1 min/60 s * 2 pi rad/rev = 178 radians/second = omega L =I * omega .0181 * 178 = 3.22 kg m^2/s final omega = initial omega - alpha t alpha (4.6) = -178 alpha = - 38.7 radians/s^2 Torque = I alpha = -.0181 (38...

Physic Moment of inertia
I = (2/5) m r^2 = (2/5)(11.1)(.630) = 2.8 kg m^2

Help!! Physics
c = speed of light = 3 * 10^8 m/s 199 = c T T =199/3*10^8 f = 1/T = 300* 10^6/199 = 1.51 * 10^6 Hz omega = 2 pi f = 9.47 * 10^6 omega^2 = 1/(LC) = 89.7*10^12 so C (785 * 10^-6) = (1/89.7) 10^-12 C = (1/70414) 10^-6 = 1.42 * 10^-5*10^-6 = 1.42 * 10-11

algebra
It represents the average speed during that interval or in other words the distance traveled during that interval/ 3 seconds d(5) = 16 * 25 = 400 d(2) = 16*4 = 64 distance during those three seconds = 400-64 = 336 feet 336 ft/3 s = 112 ft/s = average speed for that interval By...

Stats
easy to say they do not happen 1-pA = .6 1-pB = .5 so probability that neither happens is .3 so probability that at least one happens is 1-.3 = .7

maths natural log
Huh ? as t--> oo e^-anything t ----> 1/ e^big ---->0 so W ---> 0 and b ---> 800 What happened was that the black increased form their initial 50 to their final 800 while destroying the white populations, typical invasive species.

Stats
http://davidmlane.com/hyperstat/z_table.html

Stats
I can not see your graph. You can not copy and paste here, but find the area in that region

math
1000 * .90 * .90 = ?

Calculus
the rate of change of volume is the surface area times the rate of change of height 450 ft^3/min = surface area * dh/dt surface area = pi r^2 450 = pi (30^2) dh/dt dh/dt = .159 ft/min You could do this by saying V = pi r^2 h dV/dh = pi r^2 dV/dh*dh/dt = pi r^2 dh/dt chain rule...

math
you mean how many zeros I think look at b^2-4ac 49 -16*8 is NEGATIVE so two complex conjugate solutions, NO real solutions

math
find the zeros of that parabola, use the + one (I turned the parabola upside down because I like positive x^2 term) .06 x^2 - 9.6 x - 5.4 = 0 use x = [-b +/- sqrt(b^2-4ac) ]/2a while I use wolfram alpha http://www.wolframalpha.com/input/?i=+.06+x^2+-+9.6+x+-+5.4+%3D+0++ to get...

Physics
A) we pushed back on the snow Therefore Prof. Newton says (Law #3) that the snow pushes forward on us B) 410 forward - 187 backward = 223 N forward C) F = m a 223 = 530 (the driver evidently has no mass:) * a so a = 223/530 = .421 m/s^2 D) v = Vi + a t v = 0 + .421 (7.3) v = 3...

Science (check please)
Good, you are welcome :)

Science (check please)
agree

Math/precalc
Sorry tangent period is pi, not 2 pi so (2/3) x = 1 pi x = 3 pi/2 = period

Math/precalc
I do not think amplitude means much for a tangent function which goes to infinity twice a period so I would not say 3 but maybe undefined. when the x term increases to 2 pi from 0 we have gone a period so (2/3) x = 2 pi x = 3 pi when we have gone a period period = 3 pi

Pre calc
Oh, sorry, tangent repeats every pi, not 2 pi so period is 2 pi, not 4 pi

Pre calc
argument of tan = (x/2 + pi/8) when x = 0 right now argument of tan = (pi/8) what will x be when this is bigger by two pi? (x/2 + pi/8) = (2 pi + pi/8) or x/2 = 2 pi x = 4 pi = period or how much x has to increase to go a whole way around 2 pi radians

math
You are welcome:)

math
assume no calculus allowed thus complete he square to find the vertex of this parabola 16 t^2 - 20 t - 2 = -h 16 t^2 -20 t = - h + 2 t^2 - 5/4 t = - h/16 + 1/8 t^2- 5/4 t+ 25/64 = -h/16 + 8/64 + 25/64 (t - 5/8)^2 = -(1/16)(h - 33/4) so in 5/8 of a second it reaches the vertex ...

Physics
clockwise moments about support (ignoring g which cancels) (50 - 27) m - 27(.31) = 0 23 m = 8.37 m = 0.364

Math
4 x + 9 = 65 subtract 9 from both sides 4 x = 56 divide both sides by 4 x = 14

math
180 lbs/2.5 days = 72 lbs/day 72 lbs / day * 30 days = 2160 lbs about one ton, two half ton pickups full

math
It was in a steel box lined with layers and layers of bubble wrap ( one of the many ways my students use in the contest)

Calculus
so it is positive for x>.316 and for x <.316

Calculus
Note that you did the second derivative correctly. It is easier to write it their way y" = 10e^(-5x^2)(10x^2-1) It is zero at x = +/- .316

Calculus
first http://www.wolframalpha.com/input/?i=plot++e^%28-5x^2%29 Then this for second derivative and graph https://www.wolframalpha.com/input/?i=second+derivative+of+e^%28-5x^2%29

Calculus
first http://www.wolframalpha.com/input/?i=plot++e^%28-5x^2%29

Spanish needs Sra
Well, all I can say is I understand you and can follow the directions just fine, but I am no Spanish grammar expert so hope one comes along.

physics
mass 1 accelerates downward at a so mass 2 accelerates up at a tension = T mass 1: m g - T = m a so 3 g - T = 3 a mass 2: T - mg = m a so T = 2 (g+a) substitute T in mass 1 equation 3 g - 2(g+a) = 3 a g - 2 a = 3 a a = g/5 = 9.81/5 = 1.962 You could also use the total mass of ...

science (check please (:)
Wow, glad you chose the right answer :)

science (check please (:)
DO NOT USE BOTTLED WATER !!! 1. It is a waste of money 2. It fills the ocean with plastic bottle remains. That is once it gets thrown off the boats and bridges. 3. It burns up energy and resources for manufacture of bottles, distribution fuel etc etc anyway your answer is right.

science (check)
You are correct, but did you have to ask? :)

math help
for 5 days 2/5 + 1/5 + 3/5 = 6/5*5 = 30/5 Sat 3 *4/5 = 12/5 Wed -2/5 for wet Pepper 30/5 + 12/5 - 2/5 = 40/5 = 8 hours

math
http://www.jiskha.com/display.cgi?id=1396046268

science (check)
Yes, but the individuals may be fish or whatever.

Math for grade 6 peace
96 = 0.48 x x = 96/0.48

Physics
Take moment about the left end total mass = 20 + 14 + 39 = 73 kg That is force up from pivot (I am going to do force in kilograms because g will cancel everywhere.) pivot distance from left = 1.4 Distance left to 39 kg = x (our L is (x -1.4) ) moments about left end 14 * 0 - 7...

science
distance = speed * time same time, higher speed --> bigger distance

Math
x + 15 + 2x + 27 = 180 3 x = 138 x = 46

math help!!
[ (x^2+5x) - 6 ] [(x^2+5x) + 6 ] (x^2 + 5 x - 6) (x^2 + 5x + 6) now if the back of your book says (x^2 + 5 x + 6)( x^2 + 5 x - 6) That is the SAME

math help!!
You got the second one, just reversed x y = y x !

geometry
width of alley = 60 tan 40 so second building = 60 + 60 tan^2 40 =60 (1 + tan^2 40) = 110 ft

geometry
ratio of ANY lengths in similar figures is the same 12/16 = 3/4 2. Ratios of ANY areas is length ratio squared 9/16 3. 54 * 16/9 = 96

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