Thursday

February 23, 2017
Total # Posts: 1,823

**math**

substituting -x + 13 = x² + 6 x + 7 0 = x² + 7 x - 6 none of the answers are correct

*May 14, 2016*

**Math**

.25 t = 1 t = 1 / .25

*May 14, 2016*

**math**

A - 25 = B + 25 ... A - 50 = B 7(B - 100) = 2(A + 100) ... 7 B - 700 = 2 A + 200 ... 7 B = 2 A + 900 substituting ... 7(A - 50) = 2 A + 900 ... 7 A - 350 = 2 A + 900 ... 5 A = 1250 ... A = 250

*May 14, 2016*

**SCIENCE**

pressure is force per unit area 100 N / 25 cm² = 4 N/cm² the SI pressure unit is the pascal 4 N/cm² = 40000 N/m² = 4 kPa

*May 14, 2016*

**Maths -Logarithm**

3^3 = 27 log(x) = 27 log(3) x = 10^[log(x)]

*May 14, 2016*

**geometry**

hard to tell without the diagram

*May 14, 2016*

**algebra**

(a) 37% / 60% (b) 37% / 52%

*May 7, 2016*

**Physics**

momentum is conserved m bt * v bt = (m bt + m bk) * v bkbt h = ½ g t² ... 1.3 = 4.9 t² ... t = .52 s v bkbt = d / t = 2.2 m / .52 s ... v bkbt = 4.2 m/s 7 * v bt = 131 * 4.2

*May 7, 2016*

**probability help!!**

all wait times have an equal probability so the probability of being in any one of three five-minute intervals is ⅓ (a) is the 1st interval (b) is the last interval

*May 7, 2016*

**Math**

the slant height is the height of the triangles that make up the sides of the pyramid the base of the triangles is the base side length pentagonal means five triangular sides with a height of 18 and a base of 9 find the areas and add them up (or find one and multiply by 5)

*May 6, 2016*

**math**

a = 6350 [1 + (.14 / 2)]^[12 / (1/2)]

*April 19, 2016*

**physics**

the acceleration is ... 2 m/s / 14 s = .14 m/s² as the car goes up a slope, the gravitational acceleration on the car is proportional to the sine of the angle of the slope sin(Θ) = .14 m/s² / 9.8 m/s² = .014 Θ = 0.8º

*April 19, 2016*

**Math**

Given function 3x/x^2-x-12 sub in -1 for x. I get the value x=0.3. Is that right?

*April 16, 2016*

**ph science**

work = 64 N * cos(35º) * 45 m

*April 16, 2016*

**Physics**

A 0.11-kg balloon is filled with helium (density = 0.179 kg/m3). If the balloon is a sphere with a radius of 5.4 m, what is the maximum weight it can lift?

*March 28, 2016*

**Algebra**

A man paid $7.80 for 5 The grams of peanuts and 3 kg of walnuts. Walnuts are $.20 a kilogram more than peanuts how much did she pay per kilogram for each

*March 21, 2016*

**home school**

In which of the following are 1/2,5/6, and 5/8 arranged in ascending order?

*March 13, 2016*

**Math Question**

Write the fraction below as a decimal. 7 --- = 100

*March 8, 2016*

**phy 231**

at the equilibrium position, there is no energy stored in the spring, it's all in the kinetic energy of the block KE = 1/2 m v²

*March 8, 2016*

**Physics**

vertical ... 2[5 sin(θ)] / g = t ... h = 5/2 sin(θ) * t/2 horizontal ... d = 5 cos(θ) t 2h = d 5/2 sin(θ) t = 5 cos(θ) t dividing by cos(θ) t and multiplying by 2/5 tan(θ) = 2 substitute back to find t

*March 7, 2016*

**Physics**

time up equals time down flight time = 2 * 30 m/s / 10 m/s²

*March 7, 2016*

**Physics**

there are 3600 s in an hr 180 km/h = 50 m/s the average velocity during the stop is ... (50 + 0) / 2 the stopping distance is ... 25 m/s * 20 s

*March 7, 2016*

**Physics**

gravity decelerates the ball time to peak is ... 30 / 9.8 the velocity at peak is zero, so the average velocity is ... (30 + 0) / 2 peak height is average velocity, multiplied by time

*March 7, 2016*

**Physics**

it's a 3-4-5 triangle 600-800-?

*March 7, 2016*

**Math**

If a pie was cut into sixths and one cut into eighths how many pieces are there altogether?

*March 5, 2016*

**Statistics**

the upper 15% of weights are a little over one S.D. above the mean so, more than ... 764 + 33 using a z-score table ... 1.036 S.D so, more than ... 764 + (33 * 1.036)

*February 29, 2016*

**Chemistry**

-log[H⁺] = 5.42 ... [H⁺] = 10^-5.42 = 3.80E-6 Ka = [H⁺][A⁻] / [HA] ... = 3.80E-6 * 3.80E-6 / ... (.095 - 3.80E-6) ... = ?

*February 29, 2016*

**Science**

electricity

*February 29, 2016*

**Physics**

momentum = m v = .057 * 29 the units are kg·m/s

*February 25, 2016*

**Algebra**

completing the square (16 / 2)² = 64 (x + 8)²

*February 25, 2016*

**Chemistry 101**

400 T * 1.0 oz/T * $1625 / oz

*February 25, 2016*

**Math**

s^2 = (6/2)^2 + 5^2 pick another letter

*February 24, 2016*

**Geometry**

factor the numerator [n * (n + 1)] / 4 n cancel the n in the numerator and denominator (n + 1) / 4

*February 24, 2016*

**physics**

conservation of momentum (again) (2300 + 1290) * 4800 = (1290 * 5600) + (2300 * v)

*February 23, 2016*

**physics**

momentum is conserved (a) 98 * 3.2 = 235 * -v (b) 98 * 3.2 = (98 + 235) * v

*February 23, 2016*

**Algebra 2**

you have the hypotenuse and the side lengths use trig functions to find the two unknown angles (A and B) S-O-H-C-A-H-T-O-A

*February 23, 2016*

**MATHS**

7 P + 22 = 2 (5 P + 2) 7 P + 22 = 10 P + 4 18 = 3 P

*February 23, 2016*

**STATISTIC**

you are right

*February 23, 2016*

**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*