# Posts by Scott

Total # Posts: 2,430

Biomechanics
1.5 laps is 600 m 600 m / 77 s = 7.8 m/s it's a straight forward calculation typo somewhere?

stats
the dice are independent chance (probability) of a 5 is ... 1/6

the difference in the path length between the direct and reflected sound should be an odd half wavelength to facilitate cancellation ... 1/2, 3/2, 5/2... the speed of sound is 340 m/s so the wavelength is 340/440 m the diagram is an isosceles triangle with an altitude of 2 m...

math need help now
as bob says "all REGULAR n-gons are similar" C for sure (they're regular) D doesn't say "regular"

math
you're looking for an area of 80 try C

Physics
vol = m / d = 20 kg / 20Mg/m^3 = 1 L the stone displaces 1 L of water with a mass of 1 kg the stone's weight is ... 19 * g

math
pay = [\$.01 * 2^(day)] - \$.01

Physics
did your G have the right units? you are correct that either equation should work Fg = Fc ... in orbit ... recalculate, and watch your units

Science
blood comes from the body ... goes to the lungs ... comes back from the lungs ... goes back out to the body the blood drops off carbon dioxide and water in the lungs and picks up oxygen, which is carried out to the body look up the exact flow through the heart chambers ...

physics
the surface is frictionless, so T is providing acceleration to the boxes the accelerating force is transferred to the small box by friction between the boxes at some point (as T increases), the frictional force will not be enough to provide the necessary acceleration and the ...

chemistry
.100 L * .10 M/L = .010 M .010 M / 4.0 M/L = ?

chemistry
each mole of butane yields 5 moles of water a mole of gas at stp is 22.4 L 10/22.4 * 5

probability
this is a binomial result ... win or not win P(w) = .15 , P(n) = .85 (n + w)^10 ... you want the 3rd term 10C2 * .85^8 * .15^2

Physics
the acceleration is ... g sin(38.0º) d = 1/2 a t^2 ... t = ?(2d / a)

Chem
you need to combine the given reactions ... some partial and/or reversed ... to get the desired reaction 2CO2 + H2O --> C2H2 + 5/2 02 ?H = 1300 kJ 2C + 2O2 --> 2CO2 ?H = -788 kJ H2 + 1/2 O2 --> H20 ?H = -286 kJ add the 3 reactions, along with the ?H's ... cancel ...

Math
1 cm on the original is 20 cm on the transfer

chemistry
not enough nitrogen a mole of nitrogen is needed for every 3 moles of hydrogen

math
tan(?) = 250/170

Math
v = 24 (1 + .06)^385

physics
2 * vertical velocity / g 16.7 * ?2 / 9.81

Algebra
(a) m = 500 (1 + .015)^t (b) 800 = 500 (1 + .015)^t ... 1.6 = 1.015^t ... log(1.6) = t log(1.015) ... [log(1.6)] / [log(1.015)] = t

231 = -17.5x2^ - 138.5x - 27 462 = -37 x^2 - 277 x - 54 0 = -37 x^2 - 277 x - 516 use quadratic formula to find x

probability
there are 9 pairs of cards that differ by one ... 1-2, 2-3, 3-4, etc. there are 10C2 possible pairs ... 45 so the probability of a pair differing by one is 9/45 or .2 ... by more than one is (1 - .2) = .8 3 cards contain 3 pairs .8^3 = .512

physics
m g h = 1/2 m v^2 ... v = ?(2 g h)

physics
it's a fraction of a mole ... 9.1E5 / 6.02E23 multiply the fraction by the molar mass

physics
60 sec in a min 2.54 cm in an inch 9.843E4 ft/min * (1 min / 60 s) * ... (12 in / 1 ft) * (.0254 m / 1 in)

physics
f = m a = 2E3 kg * ... [(20 m/s - 5 m/s) / 4 s] answer is in Newtons

Algebra2
an = 13n - 8

Physics
convert mph to m/s convert cg(?) to kg K.E. = 1/2 m v^2

physical science
Joules of energy required ... 202 * (95.6 - 22.0) * 4.18 divide by heater wattage ... 1 watt = 1 Joule per second divide by 60 ... sec to min

Physics
friction

science
free fall...starting from rest d = 1/2 g t^2 ... plug in the times, and find the difference in the distances the 1st body will always be going faster than the 2nd, so the distance between them is always increasing

Math
the edge length is the cube root of the volume 8 in this case

Math
not enough information

Maths
the distance between the centers of the two outer circles is 4 they are in the diagonal corners, and their centers are ?2 from the corners so the diagonal of the square is ... 4 + 2?2 dividing by ?2 to find side length ... 2 + 2?2 squaring ... 4 + 4?2 + 4?2 + 8 = 12 + 8?2

Math
order counts 6P3

physics
the work ... 7.6N * 8.6m ... is equal to the block's KE 1/2 * 0.50 * v^2 = 7.6 * 8.6

Math 125
sometimes just using numbers will clarify for 2000 people ... 10 have the virus ... 8 will test pos ... 2 will not ... 1990 do not have the virus ... 199 will test pos a) 207 people test pos ... 8 of them have it ... 8/207 = .0386 b) 1793 people test neg ... 2 of them have it...

physics
20^2 = 10^2 + v^2 sin(?) = 10/20 ... north of west

College Chem
heat gained by water equals heat lost by metal 50.0 * (t - 20.0) * 4.182 = ... 1000 * (100.0 - t) * 0.50

Physics
you know the size of the disk, and the material (aluminum) calculate the volume and look up the density

Physics 202-help
15/3 = 5 ... storm distance in km 15s * 343m/s = theoretical distance the time for the light to travel is below the sig fig of the other measurements ... it can be considered instantaneous

backwards math
(6 + 6 - 5) * 4

Algebra
u = t + 7 10u + t = 3(10t + u + t + u) ... = 33t + 6u 4u = 32t solve the system by substitution or elimination

math
x (154) + (40 - x)(170) = 40 (160)

Math
v / 125 = [v / (125 + 25)] + 4/3

Physics
1) the sound goes over and back ... 2 w =5.7 * 343 2)velocity = frequency * wavelength ... v = (2.22 / 7.59) * .168 m

Physics
3 s measures the km to the lightning 5 s measures the miles

Algebra
(k - 10)(k - 2) (2x + 7)(3x - 2)

maths
45 * (1 + .10)^20

too-hard probability sir damon/reiny/steve help
"you can lead a horse to water...but you can't make him drink"

too-hard probability sir damon/reiny/steve help
this is binomial...with a twist P(b) = .4 , P(w) = .6 (b + w)^4 b^4 + 4 b^3 w + 6 b^2 w^2 + 4 b w^3 + w^4 P(w ? 0) = 1 - P(b = 4) = 1 - .4^4 P(b = 2) = 6 * .4^2 * .6^2 divide to find the conditional

Physics
the given data is unrealistic please check it

physics
the ball is uniformly accelerated by gravitational force the velocity is zero at the peak 1.5 s before the peak, the velocity is ... 1.5 * g upward 1.5 s after the peak, the velocity is ... 1.5 * g downward

PreCalc
18 t + 5 t - 5 = 12

Algebra 2
x y = k

Algebra 2
the job takes 96 people-hours so for 3 people... 96/3 hr

Exponential Equation
4E12 = 24 * e^388r ln(1.7E11) / 388 = r

Math
3 1/2 is 28 eighths

Math
the scale is logarithmic 10^(8.3 - 6.2)

Geometry
the four given sides sum to 24 so the 5th side is 6 ... 30 - 24

Algebra
x + 2y = 150 x + 4y = 260 solve the system

physics
the net force is ... f = m a ... f = 111.5 * 2.7 net force is tension minus gravity t = 111.5 (9.8 + 2.7)

Chemistry
2 KClO3 ---> 2 KCl + 3 O2 moles O2 = 3/2 * moles KCl moles KCl = mass KCl / molar mass KCl mass O2 = moles O2 * molar mass O2

chemistry
find grams of C in CO2 and grams of H in H2O convert the grams to moles (divide by the molar masses) the mole ratio will give you the empirical formula

college algebra
h = 1/2 g t^2 + v t + Ho 44 = -4.9 t^2 + 20 t + 37 solve the quadratic for t

15 ? -k/4 - 9 24 ? -k/4 96 ? -k ... -96 ? k

Chemistry
381 pm is the edge length of the cubic unit cell the atomic radius is the edge length multiplied by ... ?2 / 4

Math
2 is 12/6 so you need the lowest common multiple of 12 and 5 ... 60 60/6 = 10 ... five 2 lb bags

math
looking at the cross section, this is a circle in an equilateral triangle

math
looks good

math
plug the points into the general equation and solve the system P...1 = a - b + c Q...1 = a + b + c R...6 = 25a + 5c + c

math
P and Q are the same point need 3 DIFFERENT points

Chemistry
22.4 L/mole ... gas at stp octane is 114 g/mole 2 C8H18(g) + 25 O2(g) ---> 16 CO2 (g) + 18 H2O(l) (39.0 / 114) * 12.5 * 22.4 L

physics
work = force * distance f = 5497 / 22.1 a = f / m = 5497 / (22.1 * 3090) d = 1/2 a t^2 ... t = ?(2d / a) v = a t

Algebra
3a + 9c = 183 ... 6a + 18c = 366 6a + 13c = 276 subtract equations to eliminate a solve for c, then substitute back to find a

Algebra
(r + 3) / 79 = r / 15 15 r + 45 = 79 r

sciance
depends on the car

Physics
yes the up-thrust (bouyancy) is a function of the VOLUME of liquid displaced

the rectangle with the least perimeter is a square

Chemistry
you aren't given the atomic mass not enough data for a solution

Chemistry
the volume of hexane is ... 338 g / .66 g/mL the height of the liquid is ... (hexane vol) / (? *2.91^2)

physics
energy = 1/2 m v^2 energy / time = power

Algebra 2
a^b = 3^3 3^(1/2)^x = a^(1/6) 3^3^x = a 3^3 = a^(1/x) x = 1/b

math
the slope is the same everywhere on the line slope = (-5 - 7) / (-5 - 4)

math
the distance is constant, so speed and time are inversely proportional t / 28 = 65 / 78

Math
c (100% - 56%) = 202.92

Math
m = [(91 - 44.39) / 44.39] * 100%

physics
how thick is the ice?

math
adding equations to eliminate e ... 3d = 12 solve for d, then substitute to find e

Math
3.36E6 poeple / 3 per household = ... 1.12E6 households 2 bags per month = 24 bags per year ... 10 lbs per bag 1.12E6 * 24 * 10 = ?

Math
a square m is 10000 square cm

chem
it will appear that there are more moles of solute than are actually present you will be dividing the mass of added solute by too large a number ... this will result in the molar mass being too low

geometry
the two angles sum to 180º x + (4x + 50) = 180

Chemistry
that's what you start with ... some of it is precipitated out also, the volume of the solution is more than doubled (remaining PbCl2) / solution volume

the question specifies "chemical property"