Wednesday
December 7, 2016

Posts by Scott

Total # Posts: 1,559

Chemistry
sorry...should be 2 H₂
February 16, 2016

Chemistry
Ca is a +2 ion so 2 OH (just like the 2 H) CaH₂ + 2 H₂O --> Ca(OH)₂ + H₂
February 16, 2016

Physics
gravitational potential energy is converted to kinetic energy m g h = 1/2 m v² 9.8 * 1.8 = v² / 2
February 16, 2016

physics
the vertical launch velocity is ... 33 sin(12º) 0 = 1/2 g t² + [33 sin(12º)] t + 23 use the quadratic formula to find t ...you want the positive solution g = 9.8 m/s²
February 16, 2016

chemistry
the spectrum is the result of hydrogen's electron transitioning between energy levels the levels are fixed ... quantized (per bob)
February 16, 2016

Chemistry: stoich
molar mass of O₂ is 32 g 5 moles O₂ yields 4 moles H₂O
February 16, 2016

Chemistry
answered
February 16, 2016

physics
momentum is conserved x-component ... -8.80 [4720 / (4720 + 1180)] y-component ... -1.45 [1180 / (1180 + 4720)] v = √(x^2 + y^2) the tangent of the reference angle in quad III is ... y/x
February 16, 2016

Chemistry
the molar mass of O₂ is 32 g 3 moles of oxygen produce 2 moles of iron oxide (2.50 / 32)* 2/3 = moles of Fe₂O₃ the molar mass of Fe₂O₃ is 159.7 g
February 16, 2016

Math HELPP!!
obtuse? that means an angle greater than 90º B is correct
February 16, 2016

Math HELPP!!!!
correct
February 16, 2016

Math. PLZZZ HELP ME!!!
or B or C... not enough info in the question TOO GENERAL
February 16, 2016

Math. PLZZZ HELP ME!!!
a quadrilateral with opposite sides equal and parallel is a parallelogram the 1st three answers are various types of parallelograms a trapezoid is not
February 16, 2016

Science
the same side of the moon always faces the Earth because the moon's rotational period is equal to its orbital period if the moon had a rotational period different from its orbital period, then different sides of the moon would be facing the Earth at different times
February 16, 2016

Physics
the horizontal component of the force is... f cos(Θ) as you say... a = [f cos(Θ)] / m
February 16, 2016

Physics
no friction, so why is gravity involved? f = m a 89 = (8 + 33 + 49) a
February 16, 2016

Physics
so the maximum load (cabin plus cargo) is 3300 kg the tension is the force that will accelerate the load to .68 m/s² this is against gravity so the tension overcomes gravity (mg) PLUS accelerates the load t = m g + m a = m (g + a) ...= 3300 (9.81 + .68)
February 16, 2016

physics
work (energy) is equal to the product of the force and the distance the energy is the same for both
February 16, 2016

AP Physics 1
.12 * 5.0 * 20.0 * 220 / 1000 A * V = watts watts * 5 = watt·hr dividing by 1000 gives kw·hr
February 16, 2016

physics
constant velocity means zero acceleration f = m a f = m * 0 f = 0
February 16, 2016

Math
5280 feet in a mile 12 inches in a foot the long skinny right triangle base = half mile hypotenuse = half mile plus half inch height = √(hypot^2 - base^2) almost 15 feet
February 15, 2016

chemistry
the reaction equation is in moles so you need to convert grams of iron oxide to moles the molar mass is 159.7 (two iron plus 3 oxygen) 14.7 g / 159.7 g/mol = .092 moles the reaction equation shows 3 moles of carbon dioxide for each mole of iron oxide so .092 * 3 = .276 moles ...
February 15, 2016

URGENT! Due soon and I used 8 of 10 attempts
be careful of significant figures,,,
February 14, 2016

URGENT! Due soon and I used 8 of 10 attempts
.5^n = .145 n = log(.145) / log(.5) = 2.786 2.786 * 5730 = 1.60 x 10^4
February 14, 2016

Physics
so M2 hangs over the side? f = m a ... a = f / m ... the blocks have the same a (g - t) / M2 = t / M1
February 14, 2016

Math
volume of water is volume of pyramid minus the volume of pyramid above the water v = 480 - 480 (1 - d/10)² ...= 480 - 480 (1 - d/5 + d^2/100) ...= 96 d - 4.8 d^2 dv/dt = 96 dd/dt - 9.6 d dd/dt 2 = 96 dd/dt - 9.6 * 4 * dd/dt 2 = 96 dd/dt - 38.4 dd/dt closer than .0496, but...
February 14, 2016

Algebra
"trick" question the cosine of the complement equals the sine of the angle
February 14, 2016

Calculus
the description is of a hemisphere of radius 3 v = 2/3 π r³
February 14, 2016

Chemistry
density = mass / volume volume = mass / density v = 2.0E3 g / .785 g/mL = 2.5E3 mL careful with your units the mass is only 2 sigfig
February 14, 2016

chemistry
E = h * (c / λ) energy = Planck's constant * speed of light / wavelength λ = h * c / E h = 6.63E-34 J·s λ = 6.626E-34 * 2.998E8 / 3.211E-19 λ = 6.186E-7 m = 618.6 nm
February 14, 2016

Algebra
15 * 54 = s * 27
February 14, 2016

chem
STP corresponds to 0 ºC and 760 mm Hg the volume is directly proportional to the absolute temperature (ºK) and inversely proportional to the pressure v = 145 mL * (273 / 296) * (785 / 760)
February 14, 2016

science
yes, but the objects would not be the same size sticks could be two feet long or two meters long (same dimension, 2) but they are different sizes because of the units
February 14, 2016

chemistry
hope you mean cm^3 the molar mass of NaOH is 40 g so .05 moles in .25 L .2 M
February 14, 2016

Physics
if they pull in opposite directions with 180º between the forces the net force is zero if they pull in the same direction with 0º between the forces the net force is 200KN angles in between produce net forces in between
February 14, 2016

chemistry
the COMPOUND is carbon dioxide ... CO₂
February 14, 2016

MATH
the segment is 24 units long 7 + 5 = 12 24 / 12 = 2 so the ratio is (2 * 5):(2 * 7) or 10:14 the point is (0,6)
February 12, 2016

college algebra2
the area is proportional to the square of the side length 200 / (20^2) = 400 / L^2
February 12, 2016

college algebra2
the area is proportional to the square of the side length 280 / (18^2) = A / (6 1/4)^2
February 12, 2016

math
All, Sin, Tan, Cos...ASTC cos and tan are both >0 in quad I
February 12, 2016

Math
x^2 + y^2 = r^2 9 + 4 = 13 sin = y / r = -2 / √13 = -2√13 / 13
February 12, 2016

Math
sin^2 + cos^2 = 1 sin^2 + 2/9 = 1 sin^2 = 7/9 sin = ±√7 / 3
February 12, 2016

Cal
oops...got my axes swapped thanks, Cal
February 12, 2016

Cal
the shell method seems best the corners of the cross section are (4,0), (5,0), (5,.04), (4,.0625) not needed for solution, but helps to visualize the radius of the shell is x+2 volume = 2π * r * L * thickness = 2π * (x + 2) * (1 / x^2) * dx integration limits are 4 ...
February 12, 2016

Math
63/16 = tan(Θ) nearest degree (not tenths)
February 12, 2016

maths
better, but "motion"? measures of central tendency are: mean (average), median, and mode
February 12, 2016

maths
something is amiss in the question (besides spelling) if x is greater than 95 x+2 cannot be less than 72
February 12, 2016

Math
45º reference angle in quad II looks like A
February 12, 2016

Math
2π is a full circle...so they end at the same place π/6 + 2π = 13π/6 π/6 - 2π = -11π/6
February 12, 2016

PHYSIC 220
(a)i = [19.6 * cos(153º - 90º)] - [16.7 * cos(136º - 90º)] j = [19.6 * sin(153º - 90º)] - [16.7 * sin(136º - 90º)] k = 2.40 - 0 (b) d = √(i^2 + j^2 + k^2)
February 12, 2016

Geometry
(100% + 25%) / 100% = 5/4
February 11, 2016

Physics
watts = volts * amps = amps^2 * Ω 600 W = 6 V * 100 A = 100^2 * Ω A)energy = 1/2 * farads * (volts)^2 B)use C and R (Ω) to find the time constant of the circuit the capacitor is 95% discharged after 3 time constants
February 11, 2016

algebra
Use the rational zeros theorem to find all the real zeros of the polynomial function. Use the zeros to factor f over the real numbers. f(x)= x^4+6x^3-11x^2-24x+28 Molon
February 10, 2016

Chem
it looks red because it reflects the red wavelengths and absorbs the others
February 5, 2016

Physics
uniform acceleration means that the average speed is the numerical average of the initial speed and the final speed average speed ... (30 + 60) / 2 = 45 60 s in a min ... 60 min in an hr distance = 45 * 60 * 60 * 2 (meters)
February 5, 2016

chemistry
divide the total moles by the total L moles ... (.125 * .43) + (.017 * 1.8) Liters ... .125 + .017
February 5, 2016

math
24 * 3/8 = ?
February 3, 2016

Math
9.15 / 6.10 = 1.5
February 3, 2016

math
1 1/2 is six quarters 6 * 3 = ?
February 3, 2016

Chemistry
525 mL of .5 M solution contains (.525 * .5) moles of solute since you get 2 Cl-ions from each CaCl₂ you will need...(.525 * .5 * .5) moles of CaCl₂, dissolved in 525 mL of solution molar mass of CaCl₂ is 111 g (.5 * .5 * .525 * 111) g of CaCl₂
February 2, 2016

Math
6t + 1x + 3f = 35 + 10 = 45...(A) t + x + f = 13...(B) t = x...t - x = 0...(C) (A) - 3 (B)...3t - 2x = 6 subtracting 2(C)...t = 6 substitute back to find x and f
February 1, 2016

science
let [NO₂] equal 2x (2x)^2 = 0.0466 * (1.0 - x) 4 x^2 + 0.0466 x - 0.0466 = 0 you can use the quadratic formula to find x but answer 5 is the only one that makes sense
February 1, 2016

math
graph y = x^2 and y = x^3 (use fooplot_dot_com) the intersections are the solutions
February 1, 2016

physics
clarifying Rp = 12.5 * g Rq = 9.5 * g
February 1, 2016

physics
p and q are 4.0 m apart moments around q 4 p = (10 * 5) + (4 * 2) - (8 * 1) p = 12.5 Rp = 12.5 g moments around p 4 q = (8 * 5) * (4 * 2) - (10 * 1) q = 9.5 Rq = 9.5 g
February 1, 2016

math
there is no solution they have the same experience step value; but the starting salaries are different a Q teacher with equivalent experience will always have a $2000 higher salary than an R teacher
February 1, 2016

Math
step 6 x = y = 1 so division by x-y is division by zero a BIG no-no
February 1, 2016

math (grade6)
if Connor sold p fewer than Cassie then Cassie sold p more than Connor Connor sold 50 so Cassie sold 50+p
February 1, 2016

Physics
at one time constant (τ) the current is approx. 63% of max
January 31, 2016

science
not much info...
January 31, 2016

math
x² = 26² - 24² this is actually a Pythagorean triple...5-12-13 in this case...10-24-26
January 28, 2016

Math
4 x ≤ 17.50 - 4.50 4 x ≤ 13 x ≤ 3.25
January 28, 2016

Math- Algebra
8 n ≤ 60 dividing by 8... n ≤ 7.5
January 28, 2016

Math
14 gal and 25 mpg means you can drive 350 mi on a full tank...14 * 25 36 mi per day for 10 days is 360 mi so you have to gas up on the 10th day you can drive for 9 days before refueling
January 28, 2016

Math
8 * (30 + 4) = 240 + 32 = 272
January 28, 2016

math
9 char for the 1st position 9 for the 2nd 8 for the 3rd 7 for the 4th 26 for the 5th 9 * 9 * 8 * 7 * 26
January 28, 2016

General Chemistry
the partial pressures are the same ratio as the product moles from the reaction equation p CO₂ = 2/9 * 2.50 atm p N₂ = 1/3 * 2.50 atm p H₂O = 4/9 * 2.50 atm
January 28, 2016

Physics
the horizontal component of the stone's velocity is ...12 m/s * cos(30º) multiply by 8 s to find the distance
January 28, 2016

Physics
the speed is the vector sum of the plane and the wind north and east are perpendicular, so it's a right triangle s² = 499² + 87²
January 28, 2016

Science
looks like D
January 28, 2016

science
the normal force is...5 g cos(30º) the force along the ramp is ... 5 g sin(30º) 5 g sin(30º) = μ 5 g cos(30º) sin(30º) / cos(30º) = tan(30º) = μ
January 28, 2016

Science
good answer
January 28, 2016

Chemistry 101
one inch equals 2.54 cm a mL is the same as a cm³ the volume of the ball (in mL) is 4/3 * π * 1.26³ looks like a floater
January 28, 2016

Algebra
1/f = 1/o + 1/i 1/(1/4) = 1/(1/2) + 1/i 4 = 2 + 1/i i = 2
January 28, 2016

Chemistry 101
s.h. = 3450 / [10.65 * (99.9 - 28.5)]
January 28, 2016

Chemistry 101
mass = 1.2347 lb * 453.6 g/lb width = 1.256 ft * 30.48 cm/ft D = mass / [width * 12.6 * 45.6] the answer should be rounded to 3 significant figures
January 28, 2016

Wave
greater
January 27, 2016

science
the Sun appears to move across the sky because the Earth is rotating the Sun "moves" westward, so the Earth is rotating eastward
January 27, 2016

Math
bike...d = 6t ... d/6 = t bus... 26 - d = 30 (t - 1/3) substituting...26 - d = 30 (d/6 - 1/3) 26 - d = 5d - 10 36 = 6d
January 26, 2016

Physics
flying N at 250 km/h for 30 min should put him at 125 km N of the start the wind has pushed him 75 km N and 40 km W in 30 min so the wind is blowing 150 km/h N and 80 km/h W Vw² = 150² + 80² the tangent of the angle (west of north) is...8/15
January 26, 2016

Physics
the velocities add as vectors they are perpendicular to each other v² = 6² + 4²
January 26, 2016

Science
protons are positively charged so it would repel electrons are negatively charged so it would attract
January 26, 2016

Physics
the radius of the Earth is 6.37E3 km gravitational force is inversely proportional to the square of the distance 9.81 * (6.37E3)² = 6.44 * (6.37E3 + h)²
January 26, 2016

Coulomb's Law
the force is inversely proportional to the square of the distance (inverse-square relation) the new force is 4 times the original 1 / (1/2)² = 1 / (1/4) = 4
January 26, 2016

math
the change is $5 that is 25% (5/20) of the starting value
January 26, 2016

Math
losing time means running too slow when an hour has passed, the clock has only moved 45 min it is running at 3/4 speed (45/60) so when it shows an hour has passed, an hour and 20 min (4/3 hr) has actually passed the correct time is...10:20 AM
January 26, 2016

Physics
pressure is measured in Newtons per square meter or Pascals 20 m below the surface, there are 20 cubic meters of water stacked up 20,000 kg * 9.8 m/s² = 2.0 x 10⁵ N the water pressure is...2.0x10⁵ Pa the total pressure is...3.0x10⁵ Pa
January 26, 2016

Physics
t equals the fall time 0 = -4.9 t² + 1000 horizontal distance to target d = t * 200 km/hr convert km/hr to m/s the tangent of the angle is the height of the plane, divided by the horizontal distance to target
January 26, 2016

science
the kinetic energy of an object is equal to one half of the product of the object's mass and the square of its velocity KE = 1/2 m v²
January 26, 2016

physics
charge = capacitance * voltage coulombs = Farads * volts
January 26, 2016

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