Monday
August 29, 2016

Posts by Scott

Total # Posts: 1,227

Science
going directly from a solid to a gas is called sublimation
July 6, 2016

Physics
heat = mass * temp change * specific heat make sure the units are consistent
July 6, 2016

Calculus
the horizontal components of the two ropes' tensions balance each other the combined vertical components equal 400 N sin(60º) = T1v / 400 N T2v = 400 N - T1v cos(60º) = T1h = T2H T2 = √[(T2v)² + (T2h)²]
July 6, 2016

Chemistry
the iron is oxidized the hydrogen is reduced
July 6, 2016

Physics
80 C / .001 s = 80000 C/s = 80 kA
July 6, 2016

Math (Quadratic Equations)
(1 / A) + (1 / B) = 1 / 12 (1 / A) + [1 / (A - 7)] = 1 / 12 12 A - 84 + 12 A = A * (A - 7) 24 A - 84 = A² - 7 A 0 = A² - 31 A + 84 factor the quadratic to find A
July 6, 2016

Math
-3 is not a root the roots are ... -3±i 4, -3+i, -3-i
July 6, 2016

Math
the highest exponent is the order...and the number of roots a root is a value that makes the function equal to zero you can test values for roots ... 4 works here divide the function by (x - 4) to factor out the known root ... this leaves a quadratic ... use the quadratic ...
July 6, 2016

algebra 2-1
30 c + 40 t = 270 ... 3 c + 4 t = 27 12 c + 15 t = 105 solve the system 12 c + 16 t = 108
July 6, 2016

Analytic geometry
this is a line that is the perpendicular bisector of the line between the given points
July 6, 2016

Analytic geometry
this is an ellipse the two given points are the foci
July 6, 2016

CHEMISTRY
the 64 is a good clue the mass ratio of the components is constant amu, or grams, or tonnes ... same ratio
July 5, 2016

Physics
average velocity is ... (4 + 14) / 2 d = v t
July 5, 2016

Physics
the horizontal velocity is 6 m/s the total velocity is the vector sum of the horizontal and vertical components using Pythagoras, the vertical velocity must be 8 m/s ... it's a 3-4-5 triangle (6-8-10) B looks good
July 5, 2016

Science
(a) 7 N - 5 N = (b) the object displaced 2 N of water ... w = m g ... 2 = m * 9.8 ... the volume (in L) is equal to the mass of water (in kg) (c) the 7 N object has the same volume as 2 N of water ... its density is 7/2 water's density
July 5, 2016

Physics
μ > 85.0 / (30.0 * 9.80)
July 4, 2016

math
3000 + i = 3000 (1 + .07)⁸
July 4, 2016

Physics
m g μ = 50 N ... μ = 50 / (10 * 9.8)
July 4, 2016

Physics
momentum is mass times velocity velocity is ... Vi + (a * t) write their momenta in terms of t set the expressions equal, and solve for t
July 4, 2016

Chemistry
a mole of ANY gas occupies 22.4 L at STP the formula for ammonia (g) is NH₃ its molar mass is 17.0 g
July 4, 2016

Pre Calculus
the max is on the axis of symmetry of the parabola t = -b / 2a = -2100 / (2 * -80.6)
July 4, 2016

Physical Science
heat of fusion for ice ... 79.7 cal/g heat from iron ... 100 g * 72 ºC * 0.11 cal/g⋅ºC divide heat from iron by heat of fusion
July 4, 2016

Math
the volume of metal is ... v = 4/3 * π * (30³ - 20³) cm³ if the density units are g/cm³ then multiply v by .0078
July 4, 2016

Math
oops... k = 9 3k = 27
July 4, 2016

Math
2k + 3k + 5k = 3 * 30 cm 10k = 90 cm ... k = 10 cm a) 3 * k = 30 cm b) 90 cm + D = 4 * 33 cm ... D = 42 cm
July 4, 2016

Physics
(4 kg / 18 amu) * (1 amu / 1.7E-27 kg) careful of sig figs
July 3, 2016

Physics
emf - (internal resistance * current) = terminal voltage (Ri * .55) + 5.0 = (Ri * .18) + 5.7 emf - (1.9 * .55) = 5.0
July 3, 2016

math
x + (12½% x) = Rs. 500 1.125 x = Rs. 500
July 2, 2016

physics
h = ½ g t² ... t = √(2 * 12.0 / g) v = d / t = 7.35 m / t
July 2, 2016

physics
h = ½ g t² ... t = √(2 h / g) v = d / t = 13.5 m / t
July 2, 2016

Chemistry
the concentration is 10 Molar sample size is not a factor
July 2, 2016

Chemistry
(360 / 180) moles / .200 L = 10 M
July 2, 2016

Physics
it appears to be a format problem 1/60 = 1.67E-2 rev/s
July 1, 2016

Physics
it takes 60 s for one revolution so it must be 1/60 r/s
July 1, 2016

physics
1.6 lb / .62 lb/ft
July 1, 2016

physics
1. the distance is ... 15 km + 10 km 2. the displacement is a vector from their starting point to their finishing point use Pythagoras and trig to find the distance and direction
July 1, 2016

Chemistry
sulphuric acid is diprotic (2 H⁺) so the normality is twice the molarity
July 1, 2016

chemistry
one part 50% HCl to four parts H₂O
July 1, 2016

math
what question?
July 1, 2016

Math(HELP PLEASE )
given table?
July 1, 2016

math
the (2,½) is correct not the same as (2 , 2/1) there is only one solution
July 1, 2016

physics
0 = ½ g t² + v₀ t + h 0 = -4.9 * 6² + 24 * 6 + h
June 30, 2016

Physics
V = √(2 g h) momentum is conserved ... .2 * V = (.2 + .4) v
June 29, 2016

Calculus
v = x (16 - 2x)² solve for the volume take the 1st derivative (dv/dx), and set equal to zero solve for x test the two solutions
June 29, 2016

Math2
the distance below the mean of Bob's pumpkin (z-score) is ... (938.23 - 1029.51) / 674.29 use a z-score table to find if the value lies in the upper 55.17% of entries looks like he just missed...
June 29, 2016

Math( Assignment Due Today)
h / Da = tan(35º) Da / 42 m = tan(30º) h = 42 m * tan(35º) * tan(30º)
June 29, 2016

Physics
gravity is providing the centripetal force (keeping the satellite on a circular path) a = v² / r you have a and r, just make the units consistent (a to km OR r to m)
June 29, 2016

Physics
a = (30 - 20) km/h / 1.5 s t = (36 - 30) km/h / a
June 29, 2016

Physics
answered
June 29, 2016

math
(1 - .04) * 1000 = (.25 + .05) * t
June 28, 2016

Physics
the radius of the Earth is ... 6371 km g (at the surface) is ... 9.81 m/s² (a) using the inverse-square relation ... a / g = (7000/6371)² (b) the velocity of the satellite is ... v² / r = a ... v = √(a²/r) ... keep the units consistent by converting a...
June 28, 2016

Chemistry
there is one mole of NaCl and two moles of H₂O
June 28, 2016

Admaths
constant distance from a point is a circle, centered at the point x = k is a vertical line, tangent to the circle so the radius of the circle is k-1 (x - 1)² + (y - 2)² = (k - 1)²
June 28, 2016

math
the store buys the items for some cost (c), and then marks up the selling price to 140% of c (cost plus profit) the 10% price reduction means that the sale price is 126% of c (140 - 14) the cost (c) doesn't change, so the profit is reduced to 26% (126 - 100)
June 28, 2016

math
14 N is half of 28 N, so it must be placed twice as far from the fulcrum for equilibrium 8 * 28 = d * 14
June 27, 2016

mathemarics
A. (17,12) B. d = √(20² + 16²)
June 27, 2016

geometry
2.) (3,-½)
June 27, 2016

geometry
8 units apart in the x-direction 3 units apart in the y-direction d = √(8² + 3²)
June 27, 2016

Math
it takes 600 man-hr to reap the field 600 / (8 * 15)
June 26, 2016

chemistry
how many pairs of electrons can be put into these orbitals? s -- 1 p -- 3 d -- 5 a degenerate orbital can hold a pair of electrons
June 26, 2016

math
v(x) = x (8 - 2x)(5 - 2x)
June 26, 2016

Probability
there are 24C2 ways of selecting two movies there are 9C2 ways of selecting two Barney movies the probability is ... 9C2 / 24C2
June 25, 2016

Physics
ave. velocity = (20 + 0) / 2 = 10 m/s .04 m / 10 m/s = .004 s
June 25, 2016

math
1.2 b + .9 b = 2.1 b 2.1 b / 2 b = 1.05 1.05 - 1 = .05 = 5% profit
June 25, 2016

math
f , s , t .6 t , .5 t , t .6 t / .5 t = 1.2 = 120%
June 25, 2016

Algebra
m = 37 h - 1500
June 25, 2016

Physics
one charge is attracting and the other is repelling the 3rd charge must be farther from the larger charge and not between the two charges remember inverse square law 7.25 / (d + 20)² = 2.00 / d² 7.25 d² = 2 d² + 80 d + 800 5.25 d² - 80 d - 800 = 0 use ...
June 24, 2016

Chemistry
the molar mass of NaCl is ... 58.44 g the molar mass of KI is ... 166.00 g
June 24, 2016

Probability
it's a binomial expansion (r + t)¹⁰ ... you want the 8th term 10C7 [(40/75)³ (35/75)⁷]
June 24, 2016

Science
wavelength = velocity / frequency λ = 3.0E10 cm/s / 6.0E18 hz
June 24, 2016

Physics
the s.a. of a sphere is ... 4 π r² or ... π d² km² = 1E6 m²
June 23, 2016

math
6497 , 5579 , 5993
June 23, 2016

Math
1.11 x = 5173
June 23, 2016

Physics
(a) f = m a = .02/32 * 1E5 = 63 lb (b) yes ... Newton's 3rd Law ... equal and opposite reaction (c) .007 s * 1E5 ft/s² = 700 ft/s sounds like an air rifle
June 22, 2016

Physics
the longest wavelength (lowest energy) would be from the 2nd excited state to the 3rd excited state
June 22, 2016

Physics
the plane must fly northeasterly so that its north velocity component equals the south velocity component of the wind 250 sin(Θ) = 50 sin(45º)
June 22, 2016

Math
the height of the satellite and the line through the stations form the right angle of a right triangle there are two hypotenuses (hypoteni?), one from each of the stations to the satellite curious as to how you found A) without the height h / a = tan(87º) h / (a + 35) = ...
June 22, 2016

Physics
v² / r = g sin(2Θ) / 2
June 22, 2016

Physics
u - u/20 = 19u/20 = .95u .95² = .9025 the bullet loses about 10% of its energy (kinetic), as work passing through the plank it should stop in the 11th plank
June 22, 2016

Algebra
salary = 1800 + (sales * .042) 4824 = 1800 + .042 s 3024 = .042 s
June 21, 2016

Physical Science
(6.38E6)² / .89 = (6.38E6 + h)²
June 21, 2016

Physical Science
h = ½ g t² ... .3 = ½ * 9.8 * t² t = √(.6 / 9.8) distance = 3.1 * t
June 21, 2016

Mathematics
almost ... 12/4 = 3 ... not 8 (not an exponent)
June 21, 2016

statistics
this is a binary expansion (h + t)⁴ the term you want is...6 h² t² 6 * (2/3)² * (1/3)² = 24/81 = 8/27
June 21, 2016

Physical Science
F = G * (m₁ m₂) / r² F = 6.7E-11 * 4.8E24 / (6.4E6)² N
June 21, 2016

Math1(Please Help Me)
A.) about 99% of a normally distributed population lies within 2½ standard deviations of the mean 159 cm ± (2½ * 5 cm) 65.9 kg ± (2½ * 12.7 kg) B.) the weight seems more variable because the s.d. is a larger fraction of the mean C.) 7 cm ...
June 21, 2016

physics
d = r * t (80 * t/2) + (40 * t/2) = 60 120 t = 120 ... t = 1 r = d / t = 60 km / 1 hr = 60 km/hr
June 21, 2016

Math1
A.) the data is clustered around a central value (mean), with fewer data points towards the edges B.) from statistical software ... mean = 195.5 , s.d. = 18.33 231 lbs is 1.94 s.d. above the mean [(231 - 195.5) / 18.33] this represents 2.6% of the population .026 * 218 = 5.67...
June 20, 2016

Math
2x² + 5x - 52 = 0 (2x + 13) (x - 4) = 0 x = 4
June 20, 2016

Chemistry
you need 7 moles of HCl for a complete reaction 7 moles / .85 M/L =
June 20, 2016

algebra
x = 5 is correct
June 20, 2016

Math (pre-celc 12)
you are correct
June 20, 2016

Please Help Me!
A.) the data is clustered around a central value (mean), with fewer data points towards the edges B.) from statistical software ... mean = 195.5 , s.d. = 18.33 231 lbs is 1.94 s.d. above the mean [(231 - 195.5) / 18.33] this represents 2.6% of the population .026 * 218 = 5.67...
June 20, 2016

math
3.54E7 m / 3.00E8 m/s = 1.18E-1 s
June 20, 2016

Math
60º is 1/6 of the circle a = [π (7/2)²] / 6
June 20, 2016

math
angle?
June 20, 2016

math
answered
June 20, 2016

math
the area of an isosceles right triangle is one half the square of the hypotenuse a = 3² / 2
June 20, 2016

Math
w = 250 m / tan(50º)
June 19, 2016

Maths
adding 6 ... 2 < 2x < 18 dividing by 2 ... 1 < x < 9 integers greater than 1 and less than 9
June 19, 2016

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