# Posts by Scott

Total # Posts: 1,985

**Physics**

the car is overtaking the truck the relative speed is 30 mph ... the distance is closing ... that's why the Doppler frequency is higher apparent frequency = actual frequency * [(speed of sound) / (speed of sound - closing speed)]

*February 23, 2016*

**physics**

f = m a μ m g = m (d / t²) μ = (d / t²) / g = (1320 / 6²) / 32 the assumption is that all of the mass acts on the driving wheels

*February 22, 2016*

**math**

Solve for all real values of y: |3y+7|=|2y-1|.

*February 21, 2016*

**physics**

when it leaves the roof vertical velocity ... -7.00 sin(40º) horizontal velocity ... 7.00 cos(40º) the horizontal velocity is constant the vertical velocity is increased by gravity (acceleration) h = -1/2 g t² + v₀ t + h₀ ... t is the time of flight ...

*February 21, 2016*

**physics**

m g h = 1/2 m v² h = v² / (2 g)

*February 20, 2016*

**Physics**

the drop height is ... 1/2 g t² the times are ... 4 s ... and (4 - 2.34) s g is ... 9.81 m/s² fire up that calculator

*February 20, 2016*

**Trig**

a road is inclined at an angle of 45degrees. After driving 300 feet along this road, find the driver's increase in altitude.

*February 19, 2016*

**Ms. Sue, please help me on math!**

they are both correct

*February 18, 2016*

**Physics**

an Ampere is a Coulomb per second a Coulomb is the charge on 6.242 x 10¹⁸ electrons there are 3600 seconds in an hour .497 * 6.242E18 * 3.6E3 = answer

*February 18, 2016*

**Algebra**

they each do a fraction of the job the fractions add to one the whole job (2.2 / T) + (2.2 / J) = 1 substituting [2.2 / (J + 2)] + (2.2 / J) = 1 solve for J, add 2 to find T

*February 18, 2016*

**Chemistry**

yes, but they give you the wavelength e = h c / λ make sure your units are consistent

*February 18, 2016*

**Chemistry**

2 moles of Al to 3 moles Cl₂ use the molar masses to find the number of moles

*February 18, 2016*

**physics**

the decimal point on the mass units is incorrect Joules uses kilograms, not grams you used kg in the momentum, but not the K

*February 17, 2016*

**Physics**

in the vertical direction ... h = 1/2 g t^2 + 59 sin(32º) t in the horizontal direction ... d = 59 cos(32º) t use the axis of symmetry of the parabola to find the time for max height plug the time into the vertical equation to find the max height the initial energy ...

*February 17, 2016*

**physics**

momentum is conserved 71 * 2.5 = 59 * v the direction is negative x

*February 17, 2016*

**chemistry**

the molar mass of water is 18.0 g E = [25 * (100 - 25) * .00418] + ... [(25 / 18) * 40.6]

*February 17, 2016*

**science, chemistry**

100.0 mL * 12.0 M = v * 5.20 M

*February 17, 2016*

**Math**

7 * 1/12

*February 17, 2016*

**6th grade math median range mode**

if all the values occur equally, there is no mode

*February 17, 2016*

**Physics**

the acceleration is ... (5.31 - 1.25) / 1.05 the sine of the angle of inclination is equal to the actual acceleration divided by gravitational acceleration sin(Θ) = [(5.31 - 1.25) / 1.05] / g

*February 17, 2016*

**Algebra**

z + t + c = 1000 t = 2 z c = 15 t + 10 = 30 z + 10 z + 2z + 30z + 10 = 1000 solve for z, then substitute back to find c and t

*February 17, 2016*

**Chemisty**

a mole is Avogadro's number ... 6.02 x 10^23 so you need the mass of a third of a mole of F₂ the molar mass of F₂ is 38 g

*February 17, 2016*

**Math question/help please!**

the letters correspond to the vertices K and P are congruent as are M and R and L and Q MK and ML are sides ...not measured in degrees just post the size of any of the angles that are given

*February 17, 2016*

**science**

this is a time/temperature plot the line slopes up from 35 to 75 while the solid warms up the line levels off at 75 while the solid melts phase change the line slopes up from 75 to 126 while the liquid warms up the line levels off at 126 while the liquid boils phase change the...

*February 17, 2016*

**Chemistry**

sorry...should be 2 H₂

*February 16, 2016*

**Chemistry**

Ca is a +2 ion so 2 OH (just like the 2 H) CaH₂ + 2 H₂O --> Ca(OH)₂ + H₂

*February 16, 2016*

**Physics**

gravitational potential energy is converted to kinetic energy m g h = 1/2 m v² 9.8 * 1.8 = v² / 2

*February 16, 2016*

**physics**

the vertical launch velocity is ... 33 sin(12º) 0 = 1/2 g t² + [33 sin(12º)] t + 23 use the quadratic formula to find t ...you want the positive solution g = 9.8 m/s²

*February 16, 2016*

**chemistry**

the spectrum is the result of hydrogen's electron transitioning between energy levels the levels are fixed ... quantized (per bob)

*February 16, 2016*

**Chemistry: stoich**

molar mass of O₂ is 32 g 5 moles O₂ yields 4 moles H₂O

*February 16, 2016*

**Chemistry**

answered

*February 16, 2016*

**physics**

momentum is conserved x-component ... -8.80 [4720 / (4720 + 1180)] y-component ... -1.45 [1180 / (1180 + 4720)] v = √(x^2 + y^2) the tangent of the reference angle in quad III is ... y/x

*February 16, 2016*

**Chemistry**

the molar mass of O₂ is 32 g 3 moles of oxygen produce 2 moles of iron oxide (2.50 / 32)* 2/3 = moles of Fe₂O₃ the molar mass of Fe₂O₃ is 159.7 g

*February 16, 2016*

**Math HELPP!!**

obtuse? that means an angle greater than 90º B is correct

*February 16, 2016*

**Math HELPP!!!!**

correct

*February 16, 2016*

**Math. PLZZZ HELP ME!!!**

or B or C... not enough info in the question TOO GENERAL

*February 16, 2016*

**Math. PLZZZ HELP ME!!!**

a quadrilateral with opposite sides equal and parallel is a parallelogram the 1st three answers are various types of parallelograms a trapezoid is not

*February 16, 2016*

**Science**

the same side of the moon always faces the Earth because the moon's rotational period is equal to its orbital period if the moon had a rotational period different from its orbital period, then different sides of the moon would be facing the Earth at different times

*February 16, 2016*

**Physics**

the horizontal component of the force is... f cos(Θ) as you say... a = [f cos(Θ)] / m

*February 16, 2016*

**Physics**

no friction, so why is gravity involved? f = m a 89 = (8 + 33 + 49) a

*February 16, 2016*

**Physics**

so the maximum load (cabin plus cargo) is 3300 kg the tension is the force that will accelerate the load to .68 m/s² this is against gravity so the tension overcomes gravity (mg) PLUS accelerates the load t = m g + m a = m (g + a) ...= 3300 (9.81 + .68)

*February 16, 2016*

**physics**

work (energy) is equal to the product of the force and the distance the energy is the same for both

*February 16, 2016*

**AP Physics 1**

.12 * 5.0 * 20.0 * 220 / 1000 A * V = watts watts * 5 = watt·hr dividing by 1000 gives kw·hr

*February 16, 2016*

**physics**

constant velocity means zero acceleration f = m a f = m * 0 f = 0

*February 16, 2016*

**Math**

5280 feet in a mile 12 inches in a foot the long skinny right triangle base = half mile hypotenuse = half mile plus half inch height = √(hypot^2 - base^2) almost 15 feet

*February 15, 2016*

**chemistry**

the reaction equation is in moles so you need to convert grams of iron oxide to moles the molar mass is 159.7 (two iron plus 3 oxygen) 14.7 g / 159.7 g/mol = .092 moles the reaction equation shows 3 moles of carbon dioxide for each mole of iron oxide so .092 * 3 = .276 moles ...

*February 15, 2016*

**URGENT! Due soon and I used 8 of 10 attempts**

be careful of significant figures,,,

*February 14, 2016*

**URGENT! Due soon and I used 8 of 10 attempts**

.5^n = .145 n = log(.145) / log(.5) = 2.786 2.786 * 5730 = 1.60 x 10^4

*February 14, 2016*

**Physics**

so M2 hangs over the side? f = m a ... a = f / m ... the blocks have the same a (g - t) / M2 = t / M1

*February 14, 2016*

**Math**

volume of water is volume of pyramid minus the volume of pyramid above the water v = 480 - 480 (1 - d/10)² ...= 480 - 480 (1 - d/5 + d^2/100) ...= 96 d - 4.8 d^2 dv/dt = 96 dd/dt - 9.6 d dd/dt 2 = 96 dd/dt - 9.6 * 4 * dd/dt 2 = 96 dd/dt - 38.4 dd/dt closer than .0496, but...

*February 14, 2016*

**Algebra**

"trick" question the cosine of the complement equals the sine of the angle

*February 14, 2016*

**Calculus**

the description is of a hemisphere of radius 3 v = 2/3 π r³

*February 14, 2016*

**Chemistry**

density = mass / volume volume = mass / density v = 2.0E3 g / .785 g/mL = 2.5E3 mL careful with your units the mass is only 2 sigfig

*February 14, 2016*

**chemistry**

E = h * (c / λ) energy = Planck's constant * speed of light / wavelength λ = h * c / E h = 6.63E-34 J·s λ = 6.626E-34 * 2.998E8 / 3.211E-19 λ = 6.186E-7 m = 618.6 nm

*February 14, 2016*

**Algebra**

15 * 54 = s * 27

*February 14, 2016*

**chem**

STP corresponds to 0 ºC and 760 mm Hg the volume is directly proportional to the absolute temperature (ºK) and inversely proportional to the pressure v = 145 mL * (273 / 296) * (785 / 760)

*February 14, 2016*

**science**

yes, but the objects would not be the same size sticks could be two feet long or two meters long (same dimension, 2) but they are different sizes because of the units

*February 14, 2016*

**chemistry**

hope you mean cm^3 the molar mass of NaOH is 40 g so .05 moles in .25 L .2 M

*February 14, 2016*

**Physics**

if they pull in opposite directions with 180º between the forces the net force is zero if they pull in the same direction with 0º between the forces the net force is 200KN angles in between produce net forces in between

*February 14, 2016*

**chemistry**

the COMPOUND is carbon dioxide ... CO₂

*February 14, 2016*

**MATH**

the segment is 24 units long 7 + 5 = 12 24 / 12 = 2 so the ratio is (2 * 5):(2 * 7) or 10:14 the point is (0,6)

*February 12, 2016*

**college algebra2**

the area is proportional to the square of the side length 200 / (20^2) = 400 / L^2

*February 12, 2016*

**college algebra2**

the area is proportional to the square of the side length 280 / (18^2) = A / (6 1/4)^2

*February 12, 2016*

**math**

All, Sin, Tan, Cos...ASTC cos and tan are both >0 in quad I

*February 12, 2016*

**Math**

x^2 + y^2 = r^2 9 + 4 = 13 sin = y / r = -2 / √13 = -2√13 / 13

*February 12, 2016*

**Math**

sin^2 + cos^2 = 1 sin^2 + 2/9 = 1 sin^2 = 7/9 sin = ±√7 / 3

*February 12, 2016*

**Cal**

oops...got my axes swapped thanks, Cal

*February 12, 2016*

**Cal**

the shell method seems best the corners of the cross section are (4,0), (5,0), (5,.04), (4,.0625) not needed for solution, but helps to visualize the radius of the shell is x+2 volume = 2π * r * L * thickness = 2π * (x + 2) * (1 / x^2) * dx integration limits are 4 ...

*February 12, 2016*

**Math**

63/16 = tan(Θ) nearest degree (not tenths)

*February 12, 2016*

**maths**

better, but "motion"? measures of central tendency are: mean (average), median, and mode

*February 12, 2016*

**maths**

something is amiss in the question (besides spelling) if x is greater than 95 x+2 cannot be less than 72

*February 12, 2016*

**Math**

45º reference angle in quad II looks like A

*February 12, 2016*

**Math**

2π is a full circle...so they end at the same place π/6 + 2π = 13π/6 π/6 - 2π = -11π/6

*February 12, 2016*

**PHYSIC 220**

(a)i = [19.6 * cos(153º - 90º)] - [16.7 * cos(136º - 90º)] j = [19.6 * sin(153º - 90º)] - [16.7 * sin(136º - 90º)] k = 2.40 - 0 (b) d = √(i^2 + j^2 + k^2)

*February 12, 2016*

**Geometry**

(100% + 25%) / 100% = 5/4

*February 11, 2016*

**Physics**

watts = volts * amps = amps^2 * Ω 600 W = 6 V * 100 A = 100^2 * Ω A)energy = 1/2 * farads * (volts)^2 B)use C and R (Ω) to find the time constant of the circuit the capacitor is 95% discharged after 3 time constants

*February 11, 2016*

**algebra**

Use the rational zeros theorem to find all the real zeros of the polynomial function. Use the zeros to factor f over the real numbers. f(x)= x^4+6x^3-11x^2-24x+28 Molon

*February 10, 2016*

**Chem**

it looks red because it reflects the red wavelengths and absorbs the others

*February 5, 2016*

**Physics**

uniform acceleration means that the average speed is the numerical average of the initial speed and the final speed average speed ... (30 + 60) / 2 = 45 60 s in a min ... 60 min in an hr distance = 45 * 60 * 60 * 2 (meters)

*February 5, 2016*

**chemistry**

divide the total moles by the total L moles ... (.125 * .43) + (.017 * 1.8) Liters ... .125 + .017

*February 5, 2016*

**math**

24 * 3/8 = ?

*February 3, 2016*

**Math**

9.15 / 6.10 = 1.5

*February 3, 2016*

**math**

1 1/2 is six quarters 6 * 3 = ?

*February 3, 2016*

**Chemistry**

525 mL of .5 M solution contains (.525 * .5) moles of solute since you get 2 Cl-ions from each CaCl₂ you will need...(.525 * .5 * .5) moles of CaCl₂, dissolved in 525 mL of solution molar mass of CaCl₂ is 111 g (.5 * .5 * .525 * 111) g of CaCl₂

*February 2, 2016*

**Math**

6t + 1x + 3f = 35 + 10 = 45...(A) t + x + f = 13...(B) t = x...t - x = 0...(C) (A) - 3 (B)...3t - 2x = 6 subtracting 2(C)...t = 6 substitute back to find x and f

*February 1, 2016*

**science**

let [NO₂] equal 2x (2x)^2 = 0.0466 * (1.0 - x) 4 x^2 + 0.0466 x - 0.0466 = 0 you can use the quadratic formula to find x but answer 5 is the only one that makes sense

*February 1, 2016*

**math**

graph y = x^2 and y = x^3 (use fooplot_dot_com) the intersections are the solutions

*February 1, 2016*

**physics**

clarifying Rp = 12.5 * g Rq = 9.5 * g

*February 1, 2016*

**physics**

p and q are 4.0 m apart moments around q 4 p = (10 * 5) + (4 * 2) - (8 * 1) p = 12.5 Rp = 12.5 g moments around p 4 q = (8 * 5) * (4 * 2) - (10 * 1) q = 9.5 Rq = 9.5 g

*February 1, 2016*

**math**

there is no solution they have the same experience step value; but the starting salaries are different a Q teacher with equivalent experience will always have a $2000 higher salary than an R teacher

*February 1, 2016*

**Math**

step 6 x = y = 1 so division by x-y is division by zero a BIG no-no

*February 1, 2016*

**math (grade6)**

if Connor sold p fewer than Cassie then Cassie sold p more than Connor Connor sold 50 so Cassie sold 50+p

*February 1, 2016*

**Physics**

at one time constant (τ) the current is approx. 63% of max

*January 31, 2016*

**science**

not much info...

*January 31, 2016*

**math**

x² = 26² - 24² this is actually a Pythagorean triple...5-12-13 in this case...10-24-26

*January 28, 2016*

**Math**

4 x ≤ 17.50 - 4.50 4 x ≤ 13 x ≤ 3.25

*January 28, 2016*

**Math- Algebra**

8 n ≤ 60 dividing by 8... n ≤ 7.5

*January 28, 2016*

**Math**

14 gal and 25 mpg means you can drive 350 mi on a full tank...14 * 25 36 mi per day for 10 days is 360 mi so you have to gas up on the 10th day you can drive for 9 days before refueling

*January 28, 2016*

**Math**

8 * (30 + 4) = 240 + 32 = 272

*January 28, 2016*

**math**

9 char for the 1st position 9 for the 2nd 8 for the 3rd 7 for the 4th 26 for the 5th 9 * 9 * 8 * 7 * 26

*January 28, 2016*