Sunday

February 26, 2017
Total # Posts: 1,840

**Maths**

z = 7/9 c

*February 25, 2017*

**math**

the east component is ... 10 cos(30º) the north component is ... 10 sin(30º) - 4 speed = ?[(east)^2 + (north)^2] tan(?) = north / east ? is degrees north of east

*February 25, 2017*

**chemistry**

the molar mass of Fe is 55.8 g [98.7 / (2 * 55.8)] * 852 kJ

*February 25, 2017*

**physics**

the ball is pulled back from the lowest point, and gains gravitational potential energy this energy becomes kinetic energy when the ball is released ... it is maximum at the low point m g h = 1/2 m v^2 ... v = ?(2 g h) use trig to find the height above the low point

*February 25, 2017*

**Algebra**

9 / .75 = x / 7.5

*February 25, 2017*

**College Algebra**

(x * .05) + [(10000 - x) * .06] = 550

*February 25, 2017*

**Chemistry**

hydrogen and hydroxide ions are neutralizing each other acid vol * molarity * hydrogens = ... base vol * molarity * hydroxides 26.3 * x * 2 = 17.45 * .425 * 1

*February 25, 2017*

**math**

p log(8.2) = q log(10.5) p / q = log(10.5) / log(8.2)

*February 25, 2017*

**Math :(:( Totally stressing ouuut ned help now.**

translation moves the object, but it maintains its orientation reflection or rotation can result in the point being up

*February 25, 2017*

**math help now plez**

type the url (web address) for the figure

*February 25, 2017*

**High School Geometry**

this is a 30-60-90 triangle m?L = 30 ° ... AK is the side opposite AL (the hypotenuse) is twice AK KL is AK times ?3 the area is 1/2 the product of the two perpendicular sides

*February 25, 2017*

**Math**

9 m x 6 m = 54 m^2 4 m x 4 m = 16 m^2

*February 24, 2017*

**Biomechanics**

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

*February 24, 2017*

**stats**

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

*February 24, 2017*

**physics help please**

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...

*February 24, 2017*

**math need help now**

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

*February 24, 2017*

**math**

you're looking for an area of 80 try C

*February 24, 2017*

**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

*February 23, 2017*

**math**

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

*February 23, 2017*

**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

*February 22, 2017*

**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 ...

*February 22, 2017*

**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 ...

*February 22, 2017*

**chemistry**

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

*February 21, 2017*

**chemistry**

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

*February 21, 2017*

**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

*February 21, 2017*

**Physics**

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

*February 21, 2017*

**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 ...

*February 21, 2017*

**Math**

1 cm on the original is 20 cm on the transfer

*February 21, 2017*

**chemistry**

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

*February 20, 2017*

**math**

tan(?) = 250/170

*February 20, 2017*

**Math**

v = 24 (1 + .06)^385

*February 20, 2017*

**physics**

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

*February 20, 2017*

**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

*February 20, 2017*

**Algebra - PLEASE HELP!**

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

*February 20, 2017*

**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

*February 19, 2017*

**physics**

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

*February 19, 2017*

**physics**

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

*February 19, 2017*

**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)

*February 19, 2017*

**physics**

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

*February 19, 2017*

**Algebra2**

an = 13n - 8

*February 19, 2017*

**Physics**

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

*February 19, 2017*

**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

*February 19, 2017*

**Physics**

friction

*February 19, 2017*

**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

*February 19, 2017*

**Math**

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

*February 19, 2017*

**Math**

not enough information

*February 19, 2017*

**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

*February 19, 2017*

**Math**

order counts 6P3

*February 18, 2017*

**physics**

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

*February 18, 2017*

**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...

*February 18, 2017*

**physics**

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

*February 17, 2017*

**College Chem**

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

*February 17, 2017*

**Physics**

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

*February 17, 2017*

**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

*February 17, 2017*

**backwards math**

(6 + 6 - 5) * 4

*February 17, 2017*

**Algebra**

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

*February 16, 2017*

**math**

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

*February 16, 2017*

**Math**

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

*February 15, 2017*

**Physics**

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

*February 15, 2017*

**Physics**

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

*February 15, 2017*

**Algebra**

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

*February 15, 2017*

**maths**

45 * (1 + .10)^20

*February 15, 2017*

**too-hard probability sir damon/reiny/steve help**

"you can lead a horse to water...but you can't make him drink"

*February 15, 2017*

**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

*February 15, 2017*

**Physics**

the given data is unrealistic please check it

*February 15, 2017*

**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

*February 14, 2017*

**PreCalc**

18 t + 5 t - 5 = 12

*February 14, 2017*

**Algebra 2**

x y = k

*February 14, 2017*

**Algebra 2**

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

*February 14, 2017*

**Exponential Equation**

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

*February 14, 2017*

**Math**

3 1/2 is 28 eighths

*February 14, 2017*

**Math**

the scale is logarithmic 10^(8.3 - 6.2)

*February 14, 2017*

**Geometry**

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

*February 14, 2017*

**Algebra**

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

*February 14, 2017*

**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)

*February 13, 2017*

**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

*February 13, 2017*

**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

*February 13, 2017*

**college algebra**

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

*February 13, 2017*

**Math! Please help!**

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

*February 13, 2017*

**Chemistry**

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

*February 13, 2017*

**Math**

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

*February 13, 2017*

**math**

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

*February 13, 2017*

**math**

looks good

*February 13, 2017*

**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

*February 13, 2017*

**math**

P and Q are the same point need 3 DIFFERENT points

*February 13, 2017*

**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

*February 12, 2017*

**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

*February 12, 2017*

**Algebra**

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

*February 12, 2017*

**Algebra**

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

*February 12, 2017*

**sciance**

depends on the car

*February 12, 2017*

**Physics**

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

*February 12, 2017*

**grade7 math**

the rectangle with the least perimeter is a square

*February 12, 2017*

**Chemistry**

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

*February 11, 2017*

**Chemistry**

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

*February 11, 2017*

**physics**

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

*February 11, 2017*

**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

*February 11, 2017*

**math**

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

*February 11, 2017*

**math**

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

*February 11, 2017*

**Math**

c (100% - 56%) = 202.92

*February 10, 2017*

**Math**

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

*February 10, 2017*