# Posts by Scott

Total # Posts: 1,994

**Science**

as the stone travels upward, its kinetic energy becomes potential energy the potential at the top is equal to the kinetic at the bottom ... e = 1/2 m v^2 = m g h ... h = ?[v^2 / (2 g)]

*February 5, 2017*

**Pre-Calculus**

?[389^2 + (389 + 50)^2]

*February 5, 2017*

**science**

h = -1/2 g t^2 + 7 t + 55 h is zero when the bottle hits the ground 0 = -4.9 t^2 + 7 t + 55 you want the positive solution

*February 5, 2017*

**Algebra2**

30 * (54/42)^2 * (26/85)

*February 4, 2017*

**physics**

do they start timing at a crest? there are 19 wavelengths between 20 crests

*February 4, 2017*

**Chemistry**

K.E. = 1/2 m v^2 look up the mass of the electron (in kg), and solve for v

*February 4, 2017*

**Math**

f = t - 20 j = 2f = 2t - 40 p = 3j = 6t - 120 9t - 180 = 340 solve for t, then substitute back

*February 3, 2017*

**Science**

Elodea uses photosynthesis to convert carbon dioxide and water into oxygen and carbohydrate the most bubbles should be in the carbon dioxide enhanced sample the degassed sample should have no bubbles the oxygen enhanced sample should be somewhere in between

*February 3, 2017*

**math**

b = 20000 (1 + .07)^6

*February 3, 2017*

**math**

this seems to be two questions 1st b + g = 30 b = g + 4 substitute to find solution 2nd 4 + 1 = 5 30 / 5 = 6 30 - 6 = 24 there are 24 of one and 6 of the other

*February 3, 2017*

**Math**

f + s = 45 s - f = 37 adding equations ... 2 s = 82

*February 3, 2017*

**Science**

velocity = distance / time

*February 3, 2017*

**Science 6th grade**

they are more massive (heavier) than the inner planets; and their greater gravities allow them to hold the lighter gasses

*February 2, 2017*

**Maths**

[(1.025 x) - 1000] * 1.025 = 23517.6

*February 2, 2017*

**Math**

(6 x)^2 + [5 (x - 4)]^2 = (7.5 x)^2

*February 2, 2017*

**Math**

f + s = 11000 ... 8 f + 8 s = 88000 5 f + 8 s = 75250 subtract equations to eliminate s 3 s = 12750

*February 1, 2017*

**Trigonometry**

theta is a Quad IV angle with a sine of -3/5 find cos, tan, sec, csc and cot

*February 1, 2017*

**algebra**

[.30(8080 - x)] + [1.0(x)] = .80(8080)

*February 1, 2017*

**MATH**

yes ... not to confused everything gets raised to the power

*February 1, 2017*

**algebra**

x + y = 48 x / 3 = (y / 6) + 5 ... 2x = y + 30 ... 2x - y = 30 add equations to eliminate y substitute back to find x

*February 1, 2017*

**math**

40000 L takes 30 pump-hr so 60000 L takes 45 pump-hr ... one and a half times as much 45 pump-hr / 9 pump = ?

*January 30, 2017*

**trig**

use the "Law of Cosines"

*January 30, 2017*

**math**

you have one equation and two unknowns there is no "unique" solution the solution is a line

*January 30, 2017*

**Chemistry**

find the energy (heat) for each step ... the mass of H2O is constant warm ice to 0ºC melt ice warm water to 100ºC boil water warm steam to 112ºC

*January 30, 2017*

**physics**

v initial = 100000 m / 3600 s v final = 0 v ave = (vi + vf) / 2 time = .85 m / (v ave) accel = vi / time

*January 29, 2017*

**math**

p = e + 10 15 p + 22 e = 446 15 (e + 10) + 22 e = 446 37 e = 296

*January 29, 2017*

**Math**

the normal line is perpendicular to the tangent the slope of the tangent is the 1st derivative normal slope ... -2 tangent slope ... 1/2 1/2 = 4 x^3 ... 1/8 = x^3 ... 1/2 = x point ... (1/2 , 1/16) equation ... y - 1/16 = -2 (x - 1/2)

*January 29, 2017*

**Probability, Stats**

d = defective , n = not defective this is a binomial distribution ... a battery is or isn't 100C2 * .985^98 * .015^2

*January 29, 2017*

**physics**

assuming flat ground distance = v^2 * sin(2?) / g

*January 29, 2017*

**physics**

235 - 92

*January 29, 2017*

**Pre Cal 12**

1400 = 900 [1 + (i / 4)]^(12 * 4) log(14 / 9) = 48 log[1 + (i / 4)]

*January 28, 2017*

**Math -**

multiplying 2nd equation by 2 ... 12x + 14y = 20 subtracting equations (to eliminate y) ... 4x = -4 solve for x, then substitute back to find y

*January 27, 2017*

**Pre Cal**

the sides are in the same ratios as the sines of their opposite angles a = c * [sin(A) / sin(C)]

*January 27, 2017*

**Geometry**

find the distance between two points on the original figure, and the same points on the dilated figure the ratio of the distances is the scale factor

*January 26, 2017*

**Math**

d = r * t twice the speed means half the time

*January 26, 2017*

**science**

the molar mass of CaO is ... 40 + 16 so 44 g contains ... [44 / (40 + 16)] moles

*January 26, 2017*

**Chemistry**

warm the ice from -15ºC to 0ºC melt the ice warm the water from 0ºC to 100ºC boil the water heat the steam to 114ºC each step has its own heat input

*January 26, 2017*

**math**

the system of equations has no solution ... the lines are parallel

*January 25, 2017*

**Chemistry**

a mL is a cm^3 a foot is ... 2.54 * 12 cm 1 ft^3 Hg ... mass = (2.54 * 12)^3 * 13.6 g multiply by g to find the weight

*January 25, 2017*

**Maths**

a1, a1 + 36, a3, a3 + 900 (a1 + 36) / a1 = (a3 + 900) / a3 1 + (36 / a1) = 1 + (900 / a3) a3 = r^2 * a1 36 = 900 / r^2 ... 6 r = 30

*January 25, 2017*

**Math**

50000 = 30000 (1 + i)^18 log(5/3) = 18 log(1 + i) .012325 = log(1 + i)

*January 25, 2017*

**math**

A = 100 * (1 + .03)^30

*January 25, 2017*

**maths**

a = 40 m/s / 2 ms = 20000 m/s^2 f = m a = .05 kg * 20000 m/s^2 answer is in Newtons

*January 25, 2017*

**Math**

divide the expression by the factor that will leave a quadratic that you can use the formula on

*January 24, 2017*

**Physics**

1) no horizontal acceleration ... v = 17 m/s * cos(34º) 2) same vertical velocity as at launch, except in opposite direction ... v = 17 m/s * sin(34º) ... downward 3) the flight time is twice the initial vertical velocity, divided by gravitational acceleration 4) the...

*January 24, 2017*

**physics**

mass * temp change * specific heat make sure the specific heat value is in Joules

*January 24, 2017*

**Geometry**

5 b + 5 b + b = 121

*January 24, 2017*

**Physics**

you're not accelerates to 12 m/s, then travels for 20 s ... that's 240 m, plus the acceleration distance d = 1/2 a t^2

*January 24, 2017*

**Geometric Progression.**

(x + 9) / x = (x + 22.5) / (x + 9) x^2 + 18 x + 81 = x^2 + 22.5 x 81 = 4.5 x a1, a2, 18, 27, 40.5

*January 24, 2017*

**Physics/Energy**

work = m g h the time is only a factor for power calculation

*January 24, 2017*

**Math**

60x + y = 87.15 subtracting equations ... 30x = 33.60 substituting ... 33.60 + y = 53.55 ... y = 19.95

*January 22, 2017*

**Matha**

compounding period?

*January 22, 2017*

**Physics**

KE = 1/2 m v^2 m = .02 kg v = (200000 / 3600) m/s answer is in Joules

*January 22, 2017*

**physics**

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

*January 22, 2017*

**Physics**

the same depth means the same pressure at the bottom the forces are equal

*January 22, 2017*

**science**

K.E. is proportional to the square of the velocity this means that the energy change from 80 kph to 70 kph is greater than the change from 10 kph to zero use (1/2 m v^2) to find the energies the lost energy (from braking) is usually frictional (heat)

*January 21, 2017*

**Maths**

each cut results in a cake that is 3/4 of the size before the cut starting with a whole cake (1) after 3 cuts ... 1 * (3/4) * (3/4) * (3/4)

*January 21, 2017*

**physics**

his energy at the bottom is the change in potential energy, minus the work of friction ... m * g * h - 520 * h ... E = (88 kg * 9.8 m/s^2 - 520 N) * 5.9 m his velocity is (from K.E. equation) ... v = ?(2 * E / m) while he is slowing down, his average velocity is ... (v + 0) / ...

*January 20, 2017*

**math**

2 x^2 + 13 x - 84 = 0 use the quadratic formula

*January 19, 2017*

**science**

the molar mass of sulfur is 32.1 g there are 6.02E23 atoms in a mole of sulfur (10.0 / 32.1) * 6.02E23

*January 19, 2017*

**Chemistry**

1. -3 means 3 "extra" electrons ... this element is atomic number 7 2. +2 means 2 "lost" electrons ... this element is atomic number 20 3. column 2, row 3

*January 18, 2017*

**math**

30 m / x = tan(78º)

*January 18, 2017*

**math**

[1 - (5/8)] * [1 - (1/6)]

*January 18, 2017*

**Geometry**

the x-distance from p1 to p2 is ... 6 - -4 the y-distance from p1 to p2 is ... 9 - -7 divide the distances by 4 to find the "length" of each step start at p1 and add consecutive steps to find the 3 division points

*January 18, 2017*

**algebra**

biologists use a Punnett square to show the geneotypes if both parents are RL, the following outcomes are equally probable ... RR, RL, LR, LL

*January 18, 2017*

**math**

2.1 = a [1/2^(1000/24360)] log(2.1) = log(a) + (1000/24360)log(1/2) 2.1606 ?

*January 18, 2017*

**MATH HELP**

the other 4 committee members come from the group of 6 faculty and 2 students ... 8C4 number of ways is ... 6P2 * 8C4

*January 18, 2017*

**Math**

a 5x5 grid has 25 blocks each block is 1/25 or 4% how many blocks for 24%

*January 18, 2017*

**Maths**

45 L is 45000 cm^3 (45000 / 2) seconds

*January 18, 2017*

**Pre-cal/trig**

the rope reaches around the corner on the 18 ft side, but not on the 22 ft side so the area is half of a 42 ft dia circle, plus a quarter of a 6 ft dia circle

*January 18, 2017*

**Math**

L = 3 T L + 15 + T + 15 = 38 substituting ... 3T + 15 + T + 15 = 38 = 4 T + 30 solve for T, then substitute back to find L

*January 18, 2017*

**Chemistry**

commercial ice cream is agitated more vigorously to aerate the mixture and increase the volume you pay for air that the manufacturer gets for free the product should probably be sold by weight, not volume

*January 17, 2017*

**Algebra**

Jacinda appears to be running 10 minute miles ... 6 mph after 1 hr, Raj has gone 6 mi ... that's when Jacinda catches him

*January 17, 2017*

**Physics**

momentum is conserved 4500 * 17.5 = v * (4500 + 1350)

*January 17, 2017*

**physics**

energy = m g h 3.9E5 = 1.3E3 * g * h

*January 17, 2017*

**physics**

friction force = centripetal force ? m g = m v^2 / r ? = v^2 / (g r)

*January 17, 2017*

**Physics**

the dimensions are given to 3 sig fig ... that's what the answer should have 1 m^3 = (3.28 ft)^3 v = 43 * 18 * 15 * 3.28^3 ft^3 ... use 3 significant figures in the answer

*January 17, 2017*

**serial dilutions**

the mix is 1.5 diluent to .5 solution each dilution results in a solution that is 1/4 the concentration of the added solution ... .5 mL / (.5 mL + 1.5 mL)

*January 17, 2017*

**Algebra 2**

?n = n^(1/2) ?(8 x^3 y^5)

*January 17, 2017*

**Algebra 2**

(7x-2)^1/4 = 5 7x - 2 = 625

*January 17, 2017*

**Math**

horizontal (x) component ... magnitude * cosine vertical (y) component ... magnitude * sine

*January 17, 2017*

**Algebra**

try this (.08 * x) + [.07 * (x - 1400)] = 217

*January 17, 2017*

**Physics**

h = 1/2 g t^2 ... ?(2h/g) = t the time is directly related to the square root of the height

*January 17, 2017*

**Physics**

cable exerts an upward force gravity exerts a downward force find the net force a = f / m

*January 17, 2017*

**Math**

the difference is -7 the 5th term is 10 differences before the 15th term

*January 16, 2017*

**physics**

average velocity during penetration is ... (500 + 0) / 2 time = distance / velocity

*January 16, 2017*

**science**

impulse is the change in momentum over time

*January 16, 2017*

**physics**

the force of the Earth on the ball is the same as the ball on the Earth f = m a use the drop time to find the velocity v = a t

*January 16, 2017*

**Math**

horizontal means zero slope set f' equal to zero and solve for x

*January 16, 2017*

**College Math - Quantitative Reasoning**

.93^3 = .804357 1 - .804357 = .195643 rounds to 19.6%

*January 16, 2017*

**College Math - Quantitative Reasoning**

what do you think is the right answer? the problem statement is not correct your calculations are fine

*January 16, 2017*

**Physics**

(a) looks good part (b) may be a "trick" question velocity is a vector quantity, while speed is a scalar the answer might be zero

*January 15, 2017*

**Chemistry**

sounds like hydrogen peroxide

*January 15, 2017*

**Math**

your work looks okay C1 is 60 times C2 ... so V1 should be 1/60 of V2

*January 15, 2017*

**Chemistry - Enthalpy**

the tea (water) loses the energy gained by the spoon 250.0 * (90.00 - 85.00) * 4.184 4 sig fig ... not 5 as in your answer

*January 14, 2017*

**Physics**

1/2 * 68.6 * (4.92^2 - 1.12^2)

*January 14, 2017*

**maths**

the whole circle is 2? ... or 20?/10 3?/10 - 20?/10 = ?

*January 13, 2017*

**math**

2L + 2W = 52 L = W + 4 substituting ... 2(W + 4) + 2W = 52 4W + 8 = 52

*January 13, 2017*

**algebra 2**

7C3 * 5C3

*January 12, 2017*

**algebra 2**

16000 is 4000 above the average 4000/3200 = 1.2 sd use a z-score table to find the probability

*January 12, 2017*