# Posts by Scott

Total # Posts: 2,565

**Maths**

a 2x3 grid (6 dots) has 15 pairs each of the pairs can be an edge or a diagonal some squares involve 4 dots ... some, only two

**physics**

a = 9.8 m/s / 5 s f = m a = m g ? a = g ? 9.8 m/s / 5 s = 9.8 m/s^2 * ?

**physics**

the forces are vectors that add by Pythagoras 60^2 + 80^2 = 100^2

**Physics**

the plane is moving inside an air mass that is moving relative to the ground the ground speed is the sum (vector) of the two speeds 345 kph, S40ºW ... 345 cos(40º) S ... 345 sin(40º) W 85 kph, NW ... 85 cos(45º) N ... 85 sin(45º) W find the vector sum ...

**stem**

m * g * h 65 * 9.8 * .2

**Chemistry**

p v = n r t ... v = n r t / p make sure the r value has the correct units

**physics**

m * g * h

**Chemistry Homework**

55.6 moles of H2O per liter x / (55.6 + x) = .25 x is the CO2 molarity

**Chemistry Homework**

mole fraction means .25 moles of CO2 for each mole of solution (along with .75 moles of H2O) molarity means moles of CO2 per LITER of solution so, how many moles of water in a liter?

**Hard Pre-Algrebra question**

the prism is 20 cubes by 17 cubes by 8 cubes cubes = 20 * 17 * 8 vol = 2 1/2 * 2 1/8 * 1 in^3

**further algebra**

it's a convergent geometric series, so you can find the sum the sum, minus 30, is the total rebound distance s = a / (1 - r) = 30 / (1 - 4/5)

**Math**

[(3 * 37) + 41] / 4 = ?

**This isn't about school**

as was stated in an earlier post we try to HELP with work, not do the work if you need to post a question here, you should be learning something from the question

**Calculus**

d/dx sin(a) = da/dx cos(a) the derivative of the sine is the cosine but the argument may also have a derivative

**Physics**

the wall is on the axis of symmetry of the parabola his initial vertical speed is ... 25 m/s * sin(45º) ... gravity slows him down to zero at his vertical peak ... the times is ... 25 * sin(45º) / 9.8 his horizontal speed is ... 25 m/s * cos(45º) ... use the ...

**Physics**

[g * (1.9 - .25)] / (.775 - .175)

**MATH**

.9 x + .4(100 - x) = .7 * 100

**Math ASAP**

yes the resulting triangles can be a range of sizes, depending on the orientation of the cut

**Algebra 1**

what's the procedure for rounding to a tenth? the egg must be ? 1.55, and < 1.65

**Math**

180 * (1 + .07)^12

**math**

remember, there is a hierarchy for operations PEMDAS

**math**

(27) - (-36)

**SCIENCE CHECK!**

photosynthesis is the process by which plants convert carbon dioxide and water into oxygen and carbohydradtes

**Geography (w/ geometry)**

the shadow is 4 times the length of the bridge (bldg height) / shadow = tan(sun elev)

**Math Ratios**

3 x = x + 8 ... x = 4 1 x + 2 x + 3 x = ?

**Algebra Concentration Problem**

x + y = 10 .65 x + .30 y = .40 * 10

**math**

it takes 600 worker-weeks (like man-hours) to build 4 mi of highway 150 worker-weeks per mile so 2400 worker-weeks can build ... 2400 / 150

**Math**

it's full at 10 half full at 9:59 a quarter full at 9:58

**maths**

SOHCAHTOA and the inverse functions draw the right triangle find the hypotenuse (Pythagoras) write the side ratios for the functions

**math**

(440 / ?) + (2 * 14)

**Chemistry**

.755 M * 10.9 / (10.9 + 57.6)

**scientific notation**

it's correct

**Physics**

5 rps to 25 rps is 20 rps in 10 s 2 rps/s = 4? rad/s^2 average rpm is 900 or 15 rps so 150 rev

**Chemistry**

Cl2 is the limiting reactant divide by the molar mass to find the number of moles m.m. Cl2 is 70.9 g

**chemistry need help so bad seriously help plz**

1 / ? = R [(1 / n?^2) - (1 / n?^2)] R = 1.097 x 10? m?¹ the starting principle quantum number (n?) for the Paschen Series is 3 the number (n?) for the 3rd line is 6

**math**

169 has an integer SQUARE root it is not 15

**math**

FOIL the two binomials

**MATH URGENT HELP!**

4% means 1% per quarter (compounding period) 10 yr is 40 quarters A = 5000 (1 + .01)^40

**Algebra 2**

180º is the negative x direction x = -12.5 , y = 0 (12.5,0)

**Science**

the trains are closing at 100 kph ... so it takes them 1 hr to pass the plane flies 90 kph for 1 hr

**Algebra**

should be .94 in last eqn...not .96

**Algebra**

10000 (1 + .08)^t = 33000 (1 - .06)^t log(10) + t log(1.08) = ... log(33) + t log(.94) t [log(1.08) - log(.94)] = ... log(33) - log(10) t = log(33 / 10) / log(1.08 / .96)

**Physics**

work is energy your work is correct you might have dropped a digit in the W equation not sure why you don't think you get it...

**Math**

A is a fixed value the other three vary statistically

**Math**

those lines around the numbers are absolute value symbols that means only positive numbers |-n| = n

**Math**

yup

**Math**

x / y = 3 / 4 4 x = 3 y

**Math**

$420 is 30% ... you want 3% your answer is ten times what it should be

**Math**

you're very generous that's a 30% commission

**MA240 Please help**

good answer

**Math**

(40 * 18) - 320 check again

**Chemistry**

a cubic decimeter (dm^3) is a liter not sure what the question is...

**Physics**

force * distance / time

**physics**

specific heat * mass * temp change

**Science**

not tellin' ya the answer but you need to keep thinking

**MATH**

5/12 (9000 + m) = 250 + m 45000 + 5 m = 3000 + 12 m

**Mathematics**

might want to check A the others look good

**chemistry**

100% * (1/2)^(120 / 4.55)

**ALGEBRA**

the "graphing form" is the vertex form f(x) = a (x - h)^2 + k ... a = 1 in this case vertex is (h,k)

**Physics**

momentum is conserved 65 kg * 2 m/s = 55 kg * v the canoe moves in the opposite direction

**Physics**

the index of the solution must be approximately the index of the material there is no refractive boundary between the material and the solution, so the material seems invisible

**Pre calc**

the height of the observer is ... h = 375 sin(25º) the height of the tower above the observer is ... h = 375 sin(39º) add the two heights to find the tower (remember to round)

**pre calc**

exact answer is given in "related questions" at bottom of page

**Algebra**

they each paint a fraction of the house ... the fractions add to one t / 10 + t / 15 = 1 3t / 30 + 2t / 30 = 1 5 t = 30

**precalc**

a) u - v b) u - 2 v c) 2 u + 4 v

**Maths**

c = 4 h 2 (c - 280) = h c = 8 (c - 280) solve for c, then substitute back to find h

**Preclc**

use the Law of Sines to find the distance from one of the people to the spot then use trig to find the height of the spot the angle at the spot is ... 180º - 75º - 45º = 60º 600 m / sin(60º) = x / sin(45º) ... x is the distance from the observer ...

**Physics**

"acquires" is an interesting term the muscle energy on the ground (like a spring), becomes gravitational potential energy during the jump it appears you have correctly calculated the height

**Physics**

looks actually correct to me

**pre calc**

because i made a typo...

**pre calc**

use the Law of Sines the angle at the ship is ... 180º - 46º - 63º 283 ft / sin(43º) = 350 ft / sin(63º) ... = x / sin(180º - 46º - 63º)

**algebra**

to save money with B ... A > B .2 m + 40 > .12 m + 56.32 .2 m > .12 m + 16.32 .08 m > 16.32 m > 204

**Precalculus**

the plane flew 360 mi east in the air but the air moved east and north ... this is the wind speed 15 mi E and 20 mi N forms a 3-4-5 triangle the wind is ... 25 mi / 2 hr ... on a bearing N of E the tangent of the bearing angle is ... 20 / 15

**math**

twice the teeth means half the revolutions teeth * speed = k = 48 * 3 = 144 96 * s = 144 ... s = 144 / 98

**physics**

nope E friction from the tires and normal force from the banking

**Math**

looks like a glass/class typo 2/3 of 30.9 kg 2 * 30.9/3 = ?

**Pre calc DUE TOMRROW**

i mis-transposed the 43º ... it should be 46º

**Pre calc DUE TOMRROW**

use the Law of Sines the angle at the ship is ... 180º - 46º - 63º 283 ft / sin(43º) = 350 ft / sin(63º) ... = x / sin(180º - 46º - 63º)

**geometry**

use ... a^2 + b^2 = c^2 ... twice

**Pre-cac**

the max is on the axis of symmetry x = 3 / 2a 15 = a (3 / 2a)^2 - 3 (3 / 2a) + 5 10 = (9 / 4a) - (9 / 2a) 10 a = 9/4 - 9/2 = - 9/4 a = -9/40

**physics**

google "uniform circular motion" look at the diagrams on wikipedia

**Math**

time = distance / velocity

**Math**

the peak of the jump lies on the axis of symmetry of the parabola ... x = -b / 2a = -21 / (2 * -16) time up equals time down time of flight (jump) = 2 * 21/32

**Chem: please help**

new conc = old conc * 15/50

**Chemistry help!!**

new conc = old conc * 15/50

**math**

? * (5/2)^2 * (8/2) * 10^6

**Chemistry**

i think you're right

**Maths**

2 (x^3 + 6^3) the sum of cubes is a standard factoring

**math**

the area for the measurements you give is not listed see "Heron's Formula"

**Math1**

100 (1 + .04)^12

**math**

.08 f + .05 s = 1330 .12 f + .02 s = 1500 solve the system using elimination or substitution

**Calculus**

integrate the derivatives Y"=6 ... y' = 6 x + c ... 4 = 6 * 1 + c ... c = -2 y' = 6 x - 2 ... y = 3 x^2 - 2 x + c ... 6 = 3 - 2 + c ... c = 5 y(x) = 3 x^2 - 2 x + 5

**physics**

a = v / t d = 1/2 a t^2

**physics/maths help damon or steve or scott**

6 V0 + 18 a = 246 V0 + 9 a = V1 3 V1 + 4.5 a = 69 subs ... 3 V0 + 27 a + 4.5 a = 69 ... times 2 ... 6 V0 + 63 a = 138 subtract to eliminate V0 ... 45 a = -108 ... a = -2.4 substitute back to find V0

**Physics**

the time of flight is the time it takes for the car to fall the difference in elevation of the two sides 21.3 - 1.8 = 1/2 * 9.8 * t^2 find t the car has to travel 61 m in time t the car's horizontal velocity is constant its vertical velocity increases due to falling ... Vv...

**Physics**

the energy is proportional to the SQUARE of the compression 4^2 = ?

**Math**

multiply the percentage (as a decimal) by the total number of students (500) to find out the numbers for the various sports then subtract the basketball number from the football number

**Math**

the built in Windows calculator (in scientific mode) works pretty well

**Math**

there are 365 compounding periods per year [1 + (.03 / 365)]^365 = 1 + APY

**chem**

the pressure is proportional to the absolute (Kelvin) temperature 1.89 / (24.0 + 273) = p / (38.0 + 273)