# Posts by Scott

Total # Posts: 2,430

**Math**

this is a Pythagorean triple ... 3-4-5 times 2 ... 6-8-10 x^2 + (x + 2)^2 = 10^2 2x^2 + 4x - 96 = 0 x^2 + 2x - 48 = 0 (x + 8) (x - 6) = 0 x = 6 ... x + 2 = 8

**Chemistry**

distributing on the right ... 3.6 v = 2.7 v + (2.7 * 4.9) subtracting 2.7 v ... .9 v = 2.7 * 4.9

**Chemistry**

How did the left side of the equation went from 3.6*V to .9V?

**Chemistry**

p₁ v₁ = p₂ v₂ 3.6 * v = 2.7 * (v + 4.9) .9 v = 2.7 * 4.9 ... v = 14.7 the evacuated flask means that no additional air was introduced into the system ... just a volume increase with a corresponding pressure decrease

**Chemistry**

A flask of known volume was filled with air to a pressure of 3.6atm. This flask was then attached to an evacuated flask of known volume and the air was allowed to expand into the flask. The final pressure of the air (in both flasks) was 2.7atm and the volume of the second ...

**physics**

a slingshot launches a rock straight upward at 25 m/s, how high does the rock go, how long is it in the air, what is the velocity and the acceleration of the rock at its highest point

**physics**

a greyhound is capable of running at 40 mph, how many meters could the greyhound run in 3 minutes at this speed, how many seconds would it take the greyhound to run 1 km at this speed

**Chemistry**

so the concentration of H⁺ from the HCl is ... 1 mole in 6 moles of water pH is based on moles of H⁺ per liter of solution water's volume is 18 mL per mole (based on the molar mass) so 6 moles is 108 mL so, [H⁺] = 1 mole / .108 L pH is the negative log of...

**Physics I - Modern**

the momentum is the product (multiply) of the relativistic mass and the velocity the relativistic mass is the rest mass multiplied by gamma (the relativistic "fudge factor") gamma = 1 / sqrt[1 - (v² / c²)] p = gamma * rest mass * v hyperphysics (web) is a ...

**math**

that is the number for all correct (or incorrect) see the answer to your other posted question

**math**

(a) it is a normal distribution (bell curve)n with the most likely score being half right (or wrong) you could plot the points using your binomial distribution from part (b) (b) the exponents in an individual term should sum to 15 only your last term does that otherwise, looks...

**Chemistry**

H₃BO₃ is triprotic (3 H⁺ per molecule) 29.15 * .025 = M * 3 * 25.0

**Algebra**

x (7 - 2x) (12 - 2x) = 33 4x³ - 38x² + 84x - 33 = 0 (9 - √15) / 2

**Physical science check my answers**

4. traveling a greater distance in the same amount of time means you went faster/slower?

**Chemistry**

a dm^3 is a liter two chloride ions per calcium chloride molecule .04 * .45 * 2

**solid mensuration**

π r² = 452 ... r = 12 the triangle formed by the chord and the radii from the ends has a central angle of 120º so 2/3 of the circle (240º / 360º), plus the area of the triangle; is the area of the larger segment

**Physics**

A. 239 = ½ * 3.7 * t² B. v = a t = -3.7 * t ... t is from part A

**Physics**

A. t = 50 ft/s / 32.2 ft/s² B. the velocity is zero at the peak ... so the average ascending velocity is 25 ft/s ... the displacement is 25 ft/s multiplied by the time from part A C. the time is half of the time from part A ... the average velocity is (50 + 25)/2 ft/s...

**Algebra**

you are correct (-11)^2 would be 121

**Math**

W = H + 4 L = W + 8 = H + 4 + 8 = H + 12 A = 2H (W + L) = 2 H (2H + 16) 512 = 4 H² + 32 H 128 = H² + 8 H 0 = H² + 8 H - 128 solve for H, then substitute back to find W and L

**trigonometry**

11π / 12 corresponds to a 15º reference angle in Q II 15º is half of 30º use a half-angle identity to find the exact value

**Physics**

the man is twice as far from the fulcrum as the rock so the effort is half the weight of the rock

**PHYSICS topic is pressure**

it is the lowered PARTIAL PRESSURE of oxygen, coupled with the increased PP of carbon dioxide that causes problems

**PHYSICS topic is pressure**

a deep well allows for little air circulation and the components of the atmosphere can stratify to a certain extent oxygen (which we need to breathe) is not the densest component the noble (inert) gas, argon, makes up about 1% of air; and is the heaviest as already mentioned, ...

**SCIENCE**

see the physics question 3 above yours

**Maths Algebra**

b = g + 334 b + g = 572 substituting ... g + 334 + g = 572

**Trig**

a sine value of .5 means a 30º reference angle in Q III, the angle is ... 180º + 30º = x

**Maths Algebra**

3/5 = 24/40 1/4 = 10/40 1/8 = 5/40 1/40 is left for foot travel 1/40 j = 2 km ... j = 80 km

**Maths Algebra**

9 is 1/4 of 1/2 of the herd 1/8 h = 9

**Algebra**

<

**Math**

46 divided by 1

**Physics**

the kinetic energy of the ball at launch equals the gravitational potential energy at the peak ½ m v² = m g h v = √(2 g h) = √(2 * 9.8 * 20) m/s

**Trigo**

the length of belt that passes over the pulleys is the same 18 * 2π * 6 = 5 * 2π * r

**Science**

yes

**Math**

the force is proportional to the area 30 N / 50 cm² = f / 1500 cm²

**mathematics**

30000 = x [1 + (.12/12)]^(5 * 12) 32500 = y [1 + (.12/12)]^(7 * 12) 36000 = z [1 + (.12/12)]^(10 * 12) find x, y, and z and add them together log(3000) = log(x) + 60 log(1.01) log(3000) - [60 log(1.01)] = log(x) 10^[log(x)] = x

**maths**

12 is the common denominator for 6, 3, and 4 10/12 - 8/12 + 15/12 = 17/12 = 1 5/12

**Math**

3/5 men...so 2/5 women the difference (1/5) equals 12 5 * 12 = ?

**Maths**

torque = force * distance 200 Nm = f * .40 m

**PreCalc**

you want the sin⁻¹ function on your calculator sin⁻¹(0.65) = Θ = .7076 , 2.4340

**Math**

8+{4 x [(2+7) / 3]} = 20

**PHYSICS/SCIENCE**

a third as much as 15.0 g

**Math**

x² + 7x + 12 = 0 (x + 3) (x + 4) = 0 x = -3 , x = -4

**Physics/Science**

150 cal to take the water to 0º C 79.7 cal/g to freeze it

**Math**

c = 3.5 x + 10

**Math-Direct Variation**

x = k y 3 = k * 6 ... k = 1/2 x = 1/2 * 2/3 = 1/3

**probability statistics**

between means ... 4000 < n < 7000 3 choices for the 1st digit ... 4, 5, 6 8 for the 2nd digit 7 for the 3rd digit 6 for the 4th digit numbers = 3 * 8 * 7 * 6

**statistics**

there are 11 letters 3 of them occur twice possible arrangements equal ... 11! / (2! * 2! * 2!)

**Calculus**

velocity is dx/dt integrating gives position t/42 = dx/dt t/42 dt = dx integrating ... t²/84 = x = 100/21

**math**

there are 9C4 ways of selecting four printers there are 5C4 ways of selecting four good printers the probability is ... 5C4 / 9C4

**Science**

the simplified range equation is ... Rmax = v² / g ... 100 = v² / g ... 100 g = v² when an object is thrown straight up, the initial kinetic energy becomes gravitational potential energy ... ½ m v² = m g h ... v² / (2 g) = h combining the two ...

**math**

b + c = 45 / 2.5 = 18 kph b - c = 39 / 3.25 = 12 kph adding equations (to eliminate c) ... 2 b = 30 kph solve for b substitute back to find c

**chemistry**

a mole contains Avogadro's number of particles 5 moles = 5 * 6.02E23

**Geometry**

90º - a = (180º - a) / 5 450 - 5a = 180 - a 270 = 4a

**Algebra/Quadratic Functions**

the minimum lies on the axis of symmetry x min = -b / 2a = -(-200) / 2*2 = 50

**Calc**

f(x) = x^2+(1000-x)^2 ... = x² + 1E6 - 2000x + x² ... = 2x² - 2000x + 1E6 the minimum is on the axis of symmetry at x=500 ... the function increases from there so as x increases (below x=500), the function decreases f(0) = 0² + (1000 - 0)² = 1000²...

**Math calculus**

s.a. = 6 s² da/dt = 12 s ds/dt v = s³ ... 8 = 2³

**Maths**

M = 2R M + 11 + R + 11 + 3 = 75 Roy's dessert ... 11 + 3 = $14 3R + 25 = 75 ... R = 50/3 Roy's meal ... $50/3

**Science**

f = 1500 * g * .2

**maths**

4 (1 / 2 μf) = 1 / Ce Ce = 2 μf / 4

**Math**

d = h cot(32º) d - 8 = h cot(43º) 8 = h [cot(32º) - cot(43º)] h = 8 / [cot(32º) - cot(43º)]

**Math**

3/5 = 6/10 ... so there were 6 groups of boys the 2/5 of the class that were girls resulted in 2 groups of 1/5 each an aside ... the girls' groups were twice as large as the boys' groups

**physics**

don't know if significant figures are an issue but there are two in the data, and four in the result

**Science**

the horizontal velocity is the total velocity multiplied by cos(30º) at the topmost point, there is no vertical velocity ... so the K.E. is ... E cos²(30º)

**Algebra**

nancy starts with $50 more, but annie can save $5 more per week 50 / 5 = 10 weeks

**physics**

h = ½ g t² + 30 t = -4.9 t² + 30 t substitute 20 for h to find the time ... use the quadratic formula the time of max h is on the axis of symmetry of the parabola ... t = -b / 2a = -30 / -9.8 ... plug in the time to find h max the velocity is zero at max h the...

**physics**

average velocity = distance / time = 42 m / 2 s = 21 m/s average velocity = (initial + current) / 2 gravity slowed the arrow for 2 sec ... current = initial - (2 * 9.8) (Vi + Vi - 19.6) / 2 = 21 m/s solve for Vi time up = time down flight time = 2 (Vi / g)

**Math**

5 pies means 20 quarters (5*4) 3 quarters per neighbor means 6 neighbors, with two quarters left over 3*6 = 18 ... 18 + 2 = 20

**I need help - precalc**

1/√3 is the tangent of 30º or π/6 ... this is the reference angle -1/√3 is the tangent of the reference angle in quadrants II and IV so the x-values are ... 5π/6, 11π/6, and 17π/6

**Math**

no it is three decimal places to the right, so it is one thousandth the value of the 1st five (10^-3)

**math**

you could say "a" percent is like "a" peanut...one it doesn't use the term "percentage" regardless, the question is not well worded (1.01 n) * .20 = 400

**biology**

the high specific heat will help keep the pond from becoming a "fish stew"

**Biochemistry**

pOH = 14 - pH = 2.5 [OH⁻] = 1.0E-2.5 = .0032 M 1.75 * .0032 = .0056 moles of KOH multiply by the molar mass to find the quantity required

**chemistry**

.250 L of a .1 M solution contains .025 moles of solute mass needed is ... .025 * 204.23 g

**Chemistry**

in general; the lower the elevation, the higher the atmospheric pressure but the pressure (barometric) varies with weather conditions B might be the best answer for this somewhat ambiguous question

**math order of operations**

PEMDAS parentheses, exponents, multiplication, division, addition, subtraction 2*2*3 = 12 12/12 = 1 10 - 1 = 9 9*7 = 63 10 + 63 = 73

**Chemistry**

volume is inversely related to pressure (Boyle's Law) P1*V1 = P2*V2 108 * 8 = 224 * V2

**math**

it's in two steps 700 is the start of the 1st step, 7.5% for 6 years ... the result becomes the start of the 2nd step, 8.25% for 4 years

**Physics**

the horizontal pulling force is ... 260 cos(30º) the vertical pulling force is ... 260 sin(30º) the coefficient of sliding friction is ... [260 cos(30º)] / ... {450 - [260 sin(30º)]}

**Math**

it could be a looong summer... there are an infinite number of solutions if n and m are the numbers ... n - m = 3¼ , or , n = m + 3¼ m can be ANY mixed number

**statistics**

2.15 is .85 below the mean this is .85/.5 s.d. (1.7) use a z-score table to find the fraction of the population in this range about .045

**I need help please - Pre-Calc**

1/√2 is the cosine of 45º (π/4) ... that is the reference angle -1/√2 is the cosine of ... ±3π/4 ... add or subtract multiples of 8π/4 to find the values on the interval x values...-13π/4, -11π/4, -5π/4, -3π/4, 3π...

**Physics**

a = f / m a = [108.1 - (10 * g)] / 10

**Physics**

f = m a f = 3 kg * (25 m/s / .10 s)

**Math**

4 - $2 1 - $5 1 - $10 1 - $50

**Chemistry**

the molar mass of silver chloride is 143.32 g the molar mass of silver is 107.87 g so the mass of silver in the processed sample is ... .2865 * 107.87 / 143.32 the processed mass divided by the original sample mass is the purity of the original sample

**science**

zero

**physics**

a boy uses a slingshot to launch a rock with a velocity of 30m/s how long does it take it to reach a height of 20m,what maximum height does the rock reach, what is the velocity of the rock at this height, what is the velocity of the rock just before it lands

**physics**

the required takeoff speed for a large airplane is 180mi/hr(80m/s)the plane is capable of accelerating at a rate of 4m/s^2 assume the plane starts at rest, determine the minimum runway length required for this plane to safely take off, a smaller airplane requires a takeoff ...

**math**

a. v = x (8 - 2x) (15 - 2x) b. x must be less than 4 (the point where the 2nd factor goes to zero)

**Chem**

CaS ... calcium sulfide

**Chem**

increasing the temperature (adding energy), will drive the reaction to the left

**math**

AC ... y = -2 x + 20 BD ... y = 1/2 x D (8,4) BD = √(64 + 16) AD = √(9 + 36) area ABD = ½ √(80 * 45) = 30 area ABEF = 10² = 100

**math**

a graphical solution seems the most straight forward B(0,0) C(10,0) E(10,10) A(5,10) F(0,10) find the equation for AC, and then the equation for BD D is the intersection of the lines calculate the lengths of BD and AD to find the area of ABD

**statistics**

the failure rate is 15% the probability of both bulbs being bad is ... .15 * .15

**Chemistry**

C₃H₈ + 5 O₂ --> 3 CO₂ + 4 H₂O 4 moles of C₃H₈ would normally produce 12 moles of CO₂ ... but there is insufficient O₂ the O₂ is 1/5 of what is necessary, so the yield will be ... 1/5 * 12 moles

**Science**

the Earth completes one revolution in 24 hr so, how long is the 40th parallel? the "rotational" radius is equal to the radius of the Earth times cos(40º) the length of the parallel (circumference) is 2π times the radius divide the circumference by 24 hr to ...

**math**

Steve is referring to the 5-12-13 Pythagorean triple

**math**

S * L = 60 S² + L² = (S + 8)² S² + (60 / S)² = (S + 8)² S² + (3600 / S²) = (S + 8)² S⁴ + 3600 = S⁴ + 16 S³ + 64 S² S³ + 4 S² - 225 = 0 S = 5

**Chemistry**

1.2E24 / 6.0E23 = 2.0 moles 4.0 moles are added