Posts by Scott
Total # Posts: 3,876

geometry
the cable is the hypotenuse of the right triangle formed by the cable, pole and ground. (height of attachment) / (cable length) = sin(60º) h / 20 m = ?3 / 2 
math
the max height is on the axis of symmetry of the parabola tmax = b / 2a = 56 / (2 * 1.9) solve for the time at max ... plug the time into the height equation to find max height 
Math
the ratio of the areas is the square of the ratio of the sides ... 3^2 : 5^2 ... 9 : 25 25 a / 9 = a + 576 
maths
a. 3 , 1/3 , 3 , 4 , 1/4 , 3/4 , 4/3 , 1/3 , 3 b. R , T , T c. R , T , R , T , T , R , T , T d. R , T , R , T , T , R , T , T , R , T , T , R , T , T , R , T , T , R , T , T 
Math
looks good 
Chemistry
Np thanks scott for the help 
Chemistry
okay ... I didn't make the stp correction for the O2 
Chemistry
First i did (1 atm x 2 L) / (K(constant) x 298.15K) = 0.081745mol Then i did (0.081748 mol O2) x (8 mol SO3 / 12 mol O2) x (80.0632 g SO3/mol) = 4.36 g SO3 
Chemistry
your number seems low 4.76 g ? 
Chemistry
Just want to double check, I ended up getting 4.363g SO3 
Chemistry
moles of S ... 8 * 25 / 256.56 moles of O ... 2 * 2.0 / 22.4 O will be the limiting reactant be aware of significant figures 
Chemistry
If 25.0 g S8 (molar mass = 256.56 g/mol) is made to react with 2.0 L O2 at 25 oC and 1.0 atm, what is the maximum amount (in grams) of SO3 produced? 
math
the 20 pieces allow you to select all of one kind, or any combination 20C5 
math 7 grd
if you google "cylinder minimum surface area" , you will find that a can whose height is equal to its diameter is the minimum surface area a "most compact" sphere fits inside, touching the cylindrical wall and the two ends 
algebra
the height forms a right triangle with the slant height as the hypotenuse and half of the base diagonal as the other leg (height)^2 = (slant height)^2  (half of base diagonal)^2 h^2 = 83.3^2  (10.8 ?2)^2 
Chemistry
heat ice to 0ºC ... 10.0 g *10.0 ºC * 2.09 J/gºC melt ice ... 10.0 g * 334 J/g heat water to 100ºC ... 10.0 g * 4.184 J/gºC * 100.0 ºC boil water ... 10.0 g * 2.23 kJ/g heat steam to 115ºC ... 10.0 g * 1.84 J/gºC * 15.0 ºC add the ... 
algebra
4 = a b^4 8 = a b^16 dividing ... 2 = b^12 ... b = 2^(1/12) substituting ... 2^2 = a 2^(1/3) ... a = 2^(5/3) 
algebra 2
v = 20000 (1  .10)^y 
physics
the refractive index (n) for water is ... 4/3 ... it is 1 for air (n air) * sin(?i) = (n water) * sin(?r) ... this is Snell's law 
Physics 2
crest to trough (half wavelength) time is 3.0 s , so 6.0 s for a full wavelength the wavelength is 8.0 m wave speed is ... 8.0 m / 6.0 s 
Math
Yeah I'm sure 5 is there because it's power cube of 5sqrt 
Math
Solve? 5 sqrt 2^3x * 64^2x+2 =32768^x 
Math
1. a) value = (23000 * .85) (1  .07)^(2023  2018) b) 5000 = (23000 * .85) (1  .07)^(year  2018) 2. a) 500 = 800 (1  .035)^(year  2017) b) 800 = 1200 (1  .035)^(2017  year) 
Math
1. A car is worth $23000 in Jan 2017 in the first year the car depreciates by 15 percent per annum and then 7 percent every year after that. a) what will the car be worth in Jan 2023? b) when will the car be worth $5000? 2. In 2017 the population of a certain animal in your ... 
Math
1. 2.34 = x (1/2)^(36 / 8.14) ... log(2.34)  [(36 / 8.14) log(1/2)] = log(x) 2. .23 = (1/2)^(t / 64.9) ... log(.23) = (t / 64.9) log(1/2) 3. x = 4000 * 5^(48 / 6) 
Math
1. Iodine131 is used to find leaks in water pipes it has a half life of 8.14 days. If 36 days have passed and there is now 2.34g left. What is the initial amount? 2. Sr85 is used in bone scans and has a half life of 64.9 days. If there is 23 percent of the sample remaining ... 
science (physics)
it starts from rest (vertically), and is accelerated by gravity 180 m = 1/2 g t^2 ... g = 9.8 m/s^2 
Chemistry
Thank you 
Chemistry
If a gas effuses 1.618 times faster than Kr (molar mass = 83.8 g/mol) what is the molar mass of the gas? 
Algebra
J  6 = 5 (D  6) + 2 ... J  6 = 5 D  28 J + 6 = 2(D + 6) + 11 ... J + 6 = 2 D + 23 5 D  22 = 2 D + 17 solve for D , substitute back to find J 
Algebra
S + L = 7 .2 S + .3 L = 1.8 ... S + 1.5 L = 9 
Science (Chem)
find moles of KCl ... 10.00 g / molar mass volume = moles KCl / 0.150 ... multiply by 1000 for mL 
Algebra
R = 2 P R + 4 = 3 (P  3) substituting ... 2 P + 4 = 3 P  9 
math
3x^2 + 12x = 14 x^2 + 4x = 14/3 x^2 + 4x + 4 = 2/3 (x + 2)^2 = 2/3 
math
2y^2 + 12y = 3 y^2 + 6y = 3/2 y^2 + 6y + 9 = 15/2 (y + 3)^2 = 15/2 
math(aka) algebra
C looks good 
math(aka) algebra
the domain means all possible values of x the range means all possible values of y the answers don't match the question 
Math
f = (2/5) (i  3i/10  3i/8  i/6) ... find f in terms of i 469 = 3i/8 + f ... substitute for f , then solve for i s = 3i/10 
math
[20 / (j  3)] + [20 / (j + 3)] = 7 20 j + 60 + 20 j  60 = 7(j  3)(j + 3) = 7 j^2  63 0 = 7 j^2  40 j  63 use quadratic formula to find j 
Math
arrange in order ... 4 , 6 , 8 , 10 , 11 , 12 , 18 , 20 8 values , so two per quartile the quartile "boundries" are the average of the numbers on either side ... 6 is the last value in the 1st quartile , 8 is the 1st value in the 2nd quartile ... so the 1st quartile ... 
Physics
weight = 700N + 500N measuring distance (d) from the 500N end ... d(700 + 500) = 2 * 700 
math
26 letters in the alphabet , 10 numbers 26 * 9 * 10^7 
Physics
130 dB is equivalent to 10 w/m^2 the area of the eardrum is ... ? r^2 = ? (8.5E3)^2 m^2 = 2.27E4 m^2 10 w/m^2 * 2.27E4 m^2 = 2.27E3 W = 2.27 mW (milliwatts) 
Physics
have you learned about significant figures did you notice the FYI 
Physics
what is incorrect? 
Physics
the power is evenly distributed over the surface of a sphere with a radius of 19.3 m 46673.5 W / (4 ? 19.3^2) m^2 calculate watts/m^2 calculate the area of the eardrum FYI ... be aware of significant figures 
geometry
as the number of sides on a regular polygon increases, it becomes more like a circle 
Algebra
G = R + 20 G  5 = 5 (R  5) substituting ... R + 15 = 5 R  25 
Algebra
10 t + u = 7t + 7u t = u + 3 substituting ... 11 u + 30 = 14 u + 21 
Math
K = 5 M K + M = 300 substitution is probably the best solution method 
Chemistry
30 moles H from NH3 ... 10 moles H from H2SO4 40 moles H yields ? moles H2 
physics
A 3 kg block is attached to an ideal spring with a force constant k=200 N/m. The block is given an initial velocity in the positive direction of magnitude u= 12 m/s and no initial displacement (xi=0). Find a) the amplitude, b) the phase angle, and c) write an equation for the ... 
Physics
Two people carry a heavy electric motor by placing it on a light board 2 meters in length. One person lifts at one end with a force of 700 N, and the other lifts the opposite end with a force of 500 N. What is the weight of the motor, where along the board is its center of ... 
science
destruction, fragmentation, and poaching all sound pretty negative ... don't you think? 
Physics
sphere volume ... 4/3 ? r^3 surface area ... 4 ? r^2 s.a. = k v^(2/3) Area209 / Area1 = k[209^(2/3)] / k[1^(2/3)] = 209^(2/3) 
Physics
angular velocity = 2 ? / 35 rad/min 
Algebra 1quick question
28/35 or 80% are ? 7.5 i think that's the definition of percentile 
Algebra
yes 
BC Calculus
x = length , y = width x + 2y = 800 ... x = 800  2y area = x y = y (800  2y) = 2 y^2 + 800 y setting the 1st derivative equal to zero will show the max value 4 y + 800 = 0 ... y = 200 
Math (Please help ASAP!!)
sure, let's all chime in correlation coefficient values are ... 1 ? cc ? 1 a greater absolute value means better correlation values close to zero (like .015) indicate very little correlation 
Science
im not sharing my knowledge but i would recommend a google search 
math
B = 5 a  1 H = 5 a + 1 V = 4 a + 5 there is not enough information to determine (a) , so there are an infinite number of solutions 
science
MUCH better 
science
#1 looks good #2 and #3 need some research 
math 11
the graph is a line one side is the true region, the other side is the false region 5 water and 7 OJ lies in the false region 
Algebra
sorry, my train of thought derailed ... the vertex is on the axis of symmetry ... the equation (for the axis) is ... x = b / 2a ... in this case ... x = (2.6) / (2 * .2) = 6.5 min # of dulcimers is ... 650 solve C(650) to find the min ave cost of dulcimers 
Algebra
the graph of a quadratic equation is a parabola when you are looking for a minimum, the parabola generally opens upward, with a minimum at the vertex ... this means a negative coefficient for the 2nd order (squared) term ... this is not the case with the equation you have ... 
Algebra
the general equation is ... y = ax^2 + bx + c plug in the three points to generate three equations in a, b, and c solve the system of equations for the three coefficients 1st one ... 3 = a(0)^2 + b(0) + c 
Trig
you could resolve the two legs into northsouth and eastwest components, and add them 
math
by Pythagoras ... x^2 + (x + 3)^2 = (x + 6)^2 2x^2 + 6x + 9 = x^2 + 12x + 36 x^2  6x  27 = 0 ... (x + 3)(x  9) = 0 
Calculus
141.96 may have too many significant figures try rounding to three digits 
Calculus
D^2 = Pn^2 + Pe^2 + 2^2 use implicit differentiation ... 2 D dD/dt = 2 Pn dPn/dt + 2 Pe dPe/dt ?(15^2 + 10^2 + 2^2) dD/dt = 15 * 55 + 10 * 175 
PreCalculus
the length of the ramp is the hypotenuse (a) sin(?) = 225/325 
PreCalculus
the base of the triangle is the eastwest line between the rangers the angle at the 1st ranger is ... 90º  32º the angle at the 2nd ranger is ... 90º  49º the 3rd angle is between the ranger stations (from the fire) ... this distance is 13 mi use the law ... 
Math
square pyramid 
math
dividing by ? ... r^2 = A / ? taking square root ... r = ?(A / ?) 
Math
tetrahedron 
Science
google potassiumargon dating 
math
the dB sale is logarithmic the intensity of A is ... 10^[(54  32) / 10] times as intense as B 
Math
so the log of the concentration is ... 11.0 logarithms are exponents ... for "common" logs (no base given), the base is 10 [H+] = 10^11 
physics  please help me!
thanks for catching that, Bob a =  4.9 , b = v sin(50º) , c = 16 t = {b ± ?[b^2  (4 a c)]} / (2 a) 
physics  please help me!
the vertical and horizontal times of flight must be the same for the windows position ... 27 m horizontal, and 16 m vertical horizontal time ... distance / velocity ... t = 27 m / v cos(50º) vertical time ... 16 m = 1/2 g t^2 + v sin(50º) t ... 0 = 4.9 t^2 + [v sin(... 
Math
google will do units conversion ... enter "liters to gallons" the question says "about" ... a liter is about a quart ... there are four quarts in a gallon 
physics  help!
find the initial vertical velocity ... 22 m/s * sin(35º) gravitational acceleration (g = 9.8 m/s^2) will slow the ball to a stop (vertically) ... the ball will then fall back down ... time up = time down time = velocity / acceleration flight time = 2 * [(initial vertical ... 
maths
(a + 3) / 2 = 5 (b + 4) / 2 = 2 
Chemistry
find the moles of KBr ... 5.00 g / molar mass KBr find energy change ... 25.0 g H2O * specific heat H2O * temperature change H2O 
physics
momentum is conserved so the momentum of the train is "distributed" to the train/box car just because your calculator displays them, there are NOT 11 sig figs in the answer 
Math
each of the 8 points is connected to the other 7 8 * 7 = 56 ... BUT ... a line from A to B is the same as a line from B to A ... so 56/2 
Math
need more information 
Math
w = t + b + h t = 9 h = t + b/2 ... h  9 = b/2 ... 2 h  18 = b b = t + h ... b = h + 9 2 h  18 = h + 9 ...solve for h , then substitute back to find b 
MATHh
let w equal the width of the frame the frame is made up of four pieces ... 20+w long, and w wide 4 * w * (20 + w) = 20 * 20 / 5 ... 80 w + 4 w^2 = 80 ... w^2 + 20 w  20 = 0 use the quadratic formula to find w 
Algebra 1
time = distance / rate (d / 14) + (d / 20) = 3 2/5 using LCD ... (10 d / 140) + (7 d / 140) = 3 2/5 17 d = 476 
physics
momentum is conserved 2285 * 13 = (2285 + 2465) * v 13  v = ? 
Algebra
when x = 4, there is a zero in the denominator (vert) as x goes to ±?, the 1st term of the expression goes to zero, leaving 6 (horiz) 
Algebra
f(x) = [(x + 3)(x  3)] / (x  3) when x = 3, there is a zero in both the numerator and denominator (hole) find f(3) to get the coordinates 
Physics
one of the parameters affecting refraction is the angle of the incoming ray this "angle of incidence" is measured relative to a normal to the surface if the incident ray is perpendicular to the medium, then the angle of incidence is zero; and there is no refraction 
Physics
c / (speed in medium) 
Physics
google "critical angle" 
math
K and A are their present ages K  4 = 2 (A  4) K = A + 6 substituting ... A + 6  4 = 2 A  8 solve for A, then substitute back to find K 
Maths
1 m per move up to 8 m ... 8 moves on the 9th move, it reaches the top and doesn't slip back