Sunday

September 25, 2016
Total # Posts: 1,255

**chemistry**

carbon dioxide is 32/44 oxygen by mass 3.70 g / (32 / 44)

*September 24, 2016*

**physical science**

weight is directly proportional to mass and gravitational acceleration ... w = m g w = 81.4 * (8.87 / 9.81)

*September 24, 2016*

**Physics**

f = m a m g - t = m a t = m g - m a = m (g - a) t = 2.45 (9.80 - 2.55) answer units are Newtons

*September 24, 2016*

**physics**

the free-fall equation is ... h = -4.9 t^2 + 12 t + Hb a. 0 = -4.9(3.4)^2 + 12(3.4) + Hb b. Tmax = -12 / (2 * -4.9) ... plug Tmax into the free-fall equation to find Hmax c. v = g(3.4 - Tmax)

*September 23, 2016*

**PHY**

h = 1.41 tan(34.7º)

*September 22, 2016*

**physics**

the increase in kinetic energy is from (equal to) the decrease in gravitational potential energy v^2 = 2 g h = 2 * 980 * 40 sin(.1 rd)

*September 19, 2016*

**Physics**

50 (5 + d) + 25 d = 200 (5 - d) 250 + 75 d = 1000 - 200 d 275 d = 750

*September 19, 2016*

**PRE-CAL**

2 = e^(11r) r = ln(2) / 11 1600 = P e^[10 ln(2) / 11]

*September 17, 2016*

**Maths**

a + b = 8 7 a^2 = 2 b^2 + 13 7 (8 - b)^2 = 2 b^2 + 13 448 - 112 b + 7 b^2 = 2 b^2 + 13 5 b^2 - 112 b + 435 = 0

*September 17, 2016*

**Physics**

from the general free fall equation 0 = -4.9 t^2 + 5 t + 98 v = -9.8 t + 5

*September 17, 2016*

**Physics**

see earlier post

*September 16, 2016*

**Ashley**

the distance equals the flight time multiplied by the horizontal component of the takeoff speed t = 2 {[s * sin(27.1º)] / g} d = t * [s * cos(27.1º)] 7.73 = 2 * s^2 * sin(27.1º / 2) / g

*September 16, 2016*

**Statistics**

see earlier submission

*September 14, 2016*

**Math**

p(not correct) = 1 - .797 p(at least one) = 1 - p(none) p(none) = (1 - .797)^3

*September 14, 2016*

**Chem**

g/ml * ml ---> g

*September 14, 2016*

**Physics**

one cycle (rotation) in 12 hrs (12 * 60 * 60) sec per cycle (1 / 43200) hz

*September 14, 2016*

**chemistry**

c - 44 = f f = (9/5 c) + 32 substituting ... c - 44 = (9/5 c) + 32

*September 13, 2016*

**precalc**

w^2 + (π/2) (w/2)^2 = 240 ft^2 w^2 [1 + (π/8)] = 240

*September 13, 2016*

**chemistry**

the ratio of NH3 to H2O is 4:6 or 2:3 NH3 / 2 = H2O / 3 NH3 = 2/3 * H2O 2/3 * 8 = ?

*September 13, 2016*

**math**

5 + 4i

*September 13, 2016*

**RPS**

6a + 5d = 6 ... a = 1 - 5d/6 (2a + d) (5a + 4d) = -80 ... 10 a^2 + 13 ad + 4 d^2 = -80 substitute for the value of a solve for d substitute back to find a

*September 12, 2016*

**math**

looks good

*September 12, 2016*

**physics**

looks like gravitational potential energy the energy equals the mass of an object, multiplied by the gravitational acceleration, multiplied by the height of the object

*September 12, 2016*

**Physics**

100 N * sin(45º) * 10 m = ? Joules

*September 12, 2016*

**Physics**

the height of the tree is ... 54 tan(30º) m

*September 8, 2016*

**algebra 2**

mary has a two hour head start she is 120 mi (2 * 60) ahead when tom starts tom catches up at 10 mph (70 - 60) it takes tom 12 hr (120 / 10) to catch up 12 hr from 8 am is 8 pm

*September 6, 2016*

**physic**

speed = wavelength * frequency so, the speeds are in the same ratio as the wavelengths sglass = sair (wglass / wair)

*August 31, 2016*

**SCIENCE**

you're multiplying 3 sf by 4 sf the result will have the smaller number of sig figs a trailing zero without a decimal point is not significant

*August 31, 2016*

**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

*August 28, 2016*

**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

*August 27, 2016*

**Chemistry**

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

*August 27, 2016*

**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

*August 27, 2016*

**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 ...

*August 27, 2016*

**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

*August 27, 2016*

**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

*August 27, 2016*

**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...

*August 27, 2016*

**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 ...

*August 25, 2016*

**math**

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

*August 24, 2016*

**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...

*August 24, 2016*

**Chemistry**

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

*August 23, 2016*

**Algebra**

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

*August 23, 2016*

**Physical science check my answers**

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

*August 23, 2016*

**Chemistry**

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

*August 22, 2016*

**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

*August 21, 2016*

**Physics**

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

*August 21, 2016*

**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...

*August 21, 2016*

**Algebra**

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

*August 21, 2016*

**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

*August 21, 2016*

**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

*August 20, 2016*

**Physics**

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

*August 20, 2016*

**PHYSICS topic is pressure**

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

*August 20, 2016*

**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, ...

*August 20, 2016*

**SCIENCE**

see the physics question 3 above yours

*August 20, 2016*

**Maths Algebra**

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

*August 20, 2016*

**Trig**

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

*August 20, 2016*

**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

*August 19, 2016*

**Maths Algebra**

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

*August 19, 2016*

**Math**

46 divided by 1

*August 17, 2016*

**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

*August 17, 2016*

**Trigo**

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

*August 17, 2016*

**Math**

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

*August 16, 2016*

**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

*August 16, 2016*

**maths**

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

*August 16, 2016*

**Math**

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

*August 16, 2016*

**Maths**

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

*August 16, 2016*

**PreCalc**

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

*August 15, 2016*

**Math**

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

*August 15, 2016*

**PHYSICS/SCIENCE**

a third as much as 15.0 g

*August 13, 2016*

**Math**

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

*August 13, 2016*

**Physics/Science**

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

*August 13, 2016*

**Math**

c = 3.5 x + 10

*August 12, 2016*

**Math-Direct Variation**

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

*August 12, 2016*

**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

*August 12, 2016*

**statistics**

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

*August 12, 2016*

**Calculus**

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

*August 10, 2016*

**math**

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

*August 10, 2016*

**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 ...

*August 8, 2016*

**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

*August 7, 2016*

**chemistry**

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

*August 7, 2016*

**Geometry**

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

*August 7, 2016*

**Algebra/Quadratic Functions**

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

*August 7, 2016*

**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...

*August 7, 2016*

**Math calculus**

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

*August 7, 2016*

**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

*August 7, 2016*

**Science**

f = 1500 * g * .2

*August 6, 2016*

**maths**

4 (1 / 2 μf) = 1 / Ce Ce = 2 μf / 4

*August 6, 2016*

**Math**

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

*August 6, 2016*

**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

*August 5, 2016*

**physics**

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

*August 5, 2016*

**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)

*August 4, 2016*

**Algebra**

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

*August 4, 2016*

**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...

*August 4, 2016*

**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)

*August 4, 2016*

**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

*August 4, 2016*

**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

*August 4, 2016*

**Math**

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

*August 4, 2016*

**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

*August 4, 2016*

**biology**

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

*August 4, 2016*