# Posts by Scott

Total # Posts: 2,495

**Pre-Calculus**

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

**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

**Algebra2**

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

**physics**

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

**Chemistry**

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

**Math**

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

**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

**math**

b = 20000 (1 + .07)^6

**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

**Math**

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

**Science**

velocity = distance / time

**Science 6th grade**

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

**Maths**

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

**Math**

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

**Math**

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

**Trigonometry**

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

**algebra**

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

**MATH**

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

**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

**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 = ?

**trig**

use the "Law of Cosines"

**math**

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

**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

**physics**

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

**math**

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

**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)

**Probability, Stats**

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

**physics**

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

**physics**

235 - 92

**Pre Cal 12**

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

**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

**Pre Cal**

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

**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

**Math**

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

**science**

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

**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

**math**

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

**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

**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

**Math**

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

**math**

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

**maths**

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

**Math**

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

**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...

**physics**

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

**Geometry**

5 b + 5 b + b = 121

**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

**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

**Physics/Energy**

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

**Math**

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

**Matha**

compounding period?

**Physics**

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

**physics**

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

**Physics**

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

**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)

**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)

**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) / ...

**math**

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

**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

**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

**math**

30 m / x = tan(78º)

**math**

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

**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

**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

**math**

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

**MATH HELP**

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

**Math**

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

**Maths**

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

**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

**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

**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

**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

**Physics**

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

**physics**

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

**physics**

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

**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

**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)

**Algebra 2**

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

**Algebra 2**

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

**Math**

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

**Algebra**

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

**Physics**

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

**Physics**

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

**Math**

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

**physics**

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

**science**

impulse is the change in momentum over time

**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

**Math**

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

**College Math - Quantitative Reasoning**

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

**College Math - Quantitative Reasoning**

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

**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

**Chemistry**

sounds like hydrogen peroxide

**Math**

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

**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

**Physics**

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

**maths**

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

**math**

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

**algebra 2**

7C3 * 5C3

**algebra 2**

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

**Science**

an oxide ion will take on two electrons calcium has two valence electrons potassium has one valence electron