Thursday
December 8, 2016

Posts by Scott

Total # Posts: 1,569

Math
multiplying by 1/3 ... (1/x) / [x^(-2/3)] = 1 / [x^(1/3)] multiplying by x^(-2/3) ... 1/x = [x^(-2/3)] / [x^(1/3)] ... = 1 / [x^(3/3)] = 1/x
July 18, 2016

physics
units conversion a = v / t d = Vave / t = 30 mph / 3.2 s
July 18, 2016

Physics
average velocity is ... (.36 + 0) / 2 t = d / v = .8 m / .18 m/s acceleration ... a = .36 m/s / t f = 80 kg * a
July 18, 2016

Math
f - s = 28 2.5 (f + s) = 2320 f + s = 928 adding equations to eliminate s ... 2 f = 956
July 17, 2016

chemistry
He⁺ because the greater charge of the nucleus keeps a "tighter" hold on the electron
July 16, 2016

physic
you need the coefficient of friction to solve this
July 16, 2016

physic
g = 32.2 ft/s (a) 3.73 * 32.2 = w (lbs) (b) 3.73 * (32.2 + 5.5) = w (c) same as (a) (d) 3.73 * (32.2 - 5.5) = w
July 16, 2016

General Physics
integration is the correct approach work (energy) = F(x) dx the force goes to zero at √2.6, and then goes negative ... this is also the point of max energy
July 15, 2016

Algebra 2
they appear to be the same line (colinear)
July 15, 2016

math 101
145 is one s.d. above the mean 68% of scores are in this range 34% are above the mean 50% of scores are below the mean that leaves 16% of scores above 145
July 15, 2016

maths
good solution, Steve
July 15, 2016

maths
actually, slope-intercept is better
July 15, 2016

maths
find the equations (point-slope) of the diagonals and set them equal
July 15, 2016

math ratios
1 + 6 = 7 7 k = 21 ... k = 3 3 water and 18 fertiliser
July 15, 2016

Physics
m g h = .12 J .012 * 9.8 * h = .12
July 14, 2016

physics
the average speed is 40 m/s so it takes 25 s to cover the km the acceleration is 3.2 m/s² ... 80 m/s / 25 s speed halfway 500 = ½ * 3.2 * t² ... find t and multiply by the acceleration to find the speed half speed 40 m/s / 3.2 m/s² = 12.5 s ...average ...
July 14, 2016

Math
the Richter scale is logarithmic 10^(8.8 - 5.3)
July 14, 2016

physics
it takes the 1st stone 2 s to reach its peak and return to the top of the tower, now going downward with the same velocity as the 2nd stone that velocity is 9.8 m/s when it reaches the ground, its velocity is 39.2 m/s...4 s * 9.8 m/s its average velocity is 24.5 m/s ... (9.8...
July 14, 2016

science
.001 moles / .5 L = .002 M
July 14, 2016

science
λ =330 m/s / 1E4 cycles/s = 33 mm
July 14, 2016

physics
the average speed is 10.0 m/s ... 70.0 m / 7.00 s 1st point speed is 5.00 m/s ... 10 = (15 + 5) / 2 acceleration is (10.0 m/s / 7.00 s)
July 13, 2016

Science
mass * [heat of vaporization + (specific heat * temp change)]
July 13, 2016

Chemistry
a mole of ANY gas occupies 22.4 L at stp (5.2 / 22.4) * Avogadro's number
July 13, 2016

Algebra
(3 / 2s) + (1 / s) = 1 / 9 27/2 + 9 = s = 45/2 b = 2/3 s = 15
July 13, 2016

physics
combined force is 2 kN each pier acts as a fulcrum in a class 2 lever system 6 m * 2 kn = 10 m * f1 4 m * 2 kn = 10 m * f2
July 12, 2016

math
f + s = 205 5 f + 15 s = 2025 ... f + 3 s = 405 subtracting equations ... 2 s = 200
July 11, 2016

Physics
1 / R + 1 / 400 = 5 / R 1 / 400 = 4 / R
July 11, 2016

Chemistry
a liter of solution has a mass of 1.114 kg 20.0% of that is H₃PO₄ ... 222.8 g the molar mass of H₃PO₄ is ... 97.99 g so the moles/L is ... 222.8 / 97.99 the 20.0 means 3 sig fig
July 11, 2016

Math
g(x) = -2 (2x - 4)³ - 1
July 11, 2016

Math
f(x) = (x + a) (x + b)² (x + c)³
July 11, 2016

maths
2 sin(21º) = cos(69º) sin(29º) = cos(61º) so it's twice sin² + cos²
July 11, 2016

math,maths
x/x + 2/x ≥ .2 1 + 2/x ≥ .2 2/x ≥ -.8 2 ≥ -.8 x -5/2 ≤ x
July 10, 2016

Math
the distance is the same 10 (s - 21) = 7 s 10 s - 210 = 7s
July 10, 2016

math
r + b = 365 ... 10 r + 10 b = 3650 9.5 r + 10 b = 3645 subtracting equations ... .5 r = 5
July 10, 2016

Pre-Calculus 11
squaring ... 9 - 6x + x² = x² - 5 x = 7/3
July 10, 2016

math
L = w + 5 w * (w + 5) = 500 w² + 5 w - 500 = 0 factoring ... (w + 25) (w - 20) = 0 w = 20 ... L = 25
July 9, 2016

Physics
heat = mass * temperature change * specific heat for the water heat = 200 g * 7.2 ºC * 1 cal/gºC heat gained by the water is the heat lost by the metal for metal heat = 95 g * 70.8 ºC * s.h. s.h. = (water heat) / (95 * 70.8) be aware of significant figures in ...
July 9, 2016

Algebra
ln(y) + 5 ln(y+1)
July 9, 2016

physics
each of the four sides of the square is 5 Ω diagonally, there are two parallel paths of two 5 Ω resistances in series each path is 10 Ω (5 + 5), and the two paths in parallel results in a net resistance of 5 Ω
July 8, 2016

physics
a hanging spring with a freely hanging mass the force (from gravity) is ... m * g = .98 N k = F / d = .98 N / .01 m = 98 N/m
July 7, 2016

PHYSICS
multiplying or dividing ...add the percent uncertainties 16 ± 2.25% the cm are cancelled in the division process...it's just a ratio
July 7, 2016

Algebra
squaring both sides ... 36 = n^(2x) multiplying by n ... 36 n = n^(2x + 1)
July 6, 2016

Algebra
the drop time is ... t = 132 ft/s / 32 ft/s² it starts from rest, so the average velocity is ... (0 + 132) / 2 ft/s the distance is ... d = drop time * average velocity
July 6, 2016

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

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