Friday

August 28, 2015
Total # Posts: 10,919

**math**

Undefined.
*August 24, 2014*

**Algebra**

(6-3w)(-W^2). We have an algebraic expression that's already factored. So what is the question? Did you mean (6-3W)(-W^2)=0 ? If so, 6-3W = 0 -3W = -6 W = 2 -W^2 = 0 W^2 = 0 W = 0 Solution Set: W = 0, and 2.
*August 24, 2014*

**algebra**

Eq1: 5r-9s = -76 Eq2: 9r+5s = 54 Multiply Eq1 by -9 and Eq2 by 5, then add: -45r + 81s = 684 +45r + 25s = 270 Sum: 106s = 954 s = 9 In Eq1, replace s with 9: 5r - 9*9 = -76 5r = 81-76 = 5 r = 1.
*August 24, 2014*

**Math**

Incomplete.
*August 24, 2014*

**Geometry**

L = 0.5W W = 2L A = L*W = 25 L * 2L = 25 3L = 25 L = 25/3 = 8.333 Sq. units. W = 2L = 2 * 8.333 = 16.666 Sq. units. P = 2W + 2L
*August 24, 2014*

**math**

Do you mean 18 is added? If so: 17,26,35. 35 + 18 = 53 So the number is 35.
*August 24, 2014*

**math**

1. X = +- Infinity. 2. X < 7.
*August 24, 2014*

**College Algebra 1**

4x^2 = 16 x^2 = 4 x^2-4 = 0. The difference of 2 squares: (x+2)(x-2) = 0 x+2 = 0 X = -2. x-2 = 0 X = 2.
*August 23, 2014*

**Science**

d = 0.5g*t^2 = ho-81 4.9*0.25^2 = ho-81 0.306 = ho-81 ho = 0.306 + 81 = 81.31 m. = Initial ht. of the balloon. V^2 = Vo^2 + 2g*ho V^2 = 0 + 19.6*81.31 = 1593.7 V = 39.9 m/s. = Final velocity.
*August 22, 2014*

**Physics**

m*g = 20kg * 9.8N/kg = 196 N = Wt. of the wagon. Fap*Cos30 - Fk = m*a Fap*cos30-30 = m*0 = 0 Fap*cos30 = 30 Fap = 30/cos30o = 34.6 N. = Force applied.
*August 22, 2014*

**science**

Density = 50g/8cm^3 = 6.25 g/cm^3
*August 22, 2014*

**math**

11,13,15,17,19,21,23. Select the number whose digits add up to 4: Answer = 13.
*August 21, 2014*

**physics**

Grade = 100%*sin A = 37.7% sin A = 37.7%/100% = 0.377 A = 22.1o To climb a hill, the angle of inclination must be less than 90o.
*August 21, 2014*

**physics**

X = 47 km. Y = 69 km. a. d^2 = X^2+Y^2 = 47^2 + 69^2 = 6970 d = 83.49 km. b. Tan A = Y/X = 69/47 = 1.46809 A = 55.74o W of S = 34.26o S of W.
*August 21, 2014*

**physics**

Tan30 = (49-14)/(X1+X2) Tan30 = 35/(19+X2) (19+X2)Tan30 = 35 (19+X2) = 35/Tan30 = 60.62 X2=60.62-19 = 41.62 Ft. from the rocks.
*August 21, 2014*

**physics**

Density = m/V = 0.70kg/(0.0642m)^3 = 2645 kg/m^3.
*August 21, 2014*

**math**

Specific Gravity
*August 21, 2014*

**Math**

N = The number. N + 0.2N = 28 1.2N = 28 N = 28/1.2 = 28/(1 1/5) = 28/(6/5) = 28 * 5/6 = 140/6 = 70/3.
*August 21, 2014*

**Algebra**

Velocity = 4.5 Ft/s. Downward. Speed = 4.5 Ft/s.
*August 21, 2014*

**physics**

distance = 4 + 2 + 4 + 2 = 12 m. Displacement = Df-Do = 0-0 = 0. Df = Final distance. Do = Starting point.
*August 21, 2014*

**physics**

Distance = 5 + 3 = 8 km. Displacement = 5-3 = 2 km.
*August 21, 2014*

**physics**

Vr = 186m[23o] + 327m[133o] X = 186*cos23 + 327*cos133 = -51.8 m/s. Y = 186*sin23 + 327*sin133 = 311.8 m/s. Tan Ar = Y/X = 311.8/-51.8 = -6.01986 Ar = -80.6o = Reference angle. A = -80.6 + 180 = 99.4o CCW = 9.4o W of N. Vr = Y/sin A = 311.8/sin99.4)=316 m/s [99.4o] = 316 m/s[9...
*August 21, 2014*

**physics**

Vs = 3.12 - 1.35 = 1.77 m/s.
*August 21, 2014*

**Physics**

Vo = 25m/s[30o] Vx = 25*cos30 = 21.65 m/s. Vy = 25*sin30 = 12.50 m/s. h=(V^2-Vy^2)/2g=(0-(12.5^2)/-19.6=7.97 m Range = Vo^2*sin(2A)/g Range = 25^2*sin(60)/9.8 = 55.23 m. V=Vy + g*t = 12.50 + (-9.8*2) = -7.1m/s 21.65 - 7.1i=22.78m/s[-18.16o]=Velocity 2 seconds after the launch...
*August 19, 2014*

**physics**

Cannot solve without graphs.
*August 19, 2014*

**Physics**

a. X = 30km/h Y = 40km/h Tan A = Y/X = 40/30 = 1.33333 A = 53.13o E. of N. if wind is coming from the West. = 53.13o W. of N. if wind is coming from the East. V = Y/sin A=40/sin53.13=50 km/h[53.13o]
*August 19, 2014*

**math**

Thanks! I thought it was 30o from the x axis, because the problem didn't say 30o East of North.
*August 18, 2014*

**math**

D = 90km[30o] + 150km[0o] X = 90*Cos30 + 150 = 228 km. Y = 90*sin30 = 45 km. Tan A = Y/X = 45/228 = 0.19742 A = 11.17o D=X/CosA = 228/Cos11.17=232 km[11.17o] Dx = 232*cos11.17 = 227.998 km East of starting point.
*August 18, 2014*

**math**

5*15 + 2 = 77 6*15 + 2 = 92
*August 18, 2014*

**math**

d = 1in/Xmi. * M mi = M/X inches.
*August 18, 2014*

**math**

P = Po + 0.5Po = $81. 1.5Po = 81 Po = $54 = Initial price or Cost.
*August 18, 2014*

**geometry**

9<n<14 Values of n: 10, 11, 12, 13. Sum = 10+11+12+13 = 46 cm. 5<n<9 Values of n: 6, 7, 8. Sum = 6+7+8 = 21 cm. n = 5 cm(Isosceles Triangle). n = 9 cm(Isosceles Triangle). Sum Total=5+6+7+8+9+10+11+12+13 = 81 cm.
*August 17, 2014*

**mat**

6.5Ft/3in = 2.17Ft/in Depth = 5 + 2.17x X = The # of inches of rain.
*August 17, 2014*

**Physics**

Yes, I'm glad it didn't fall on MY head!
*August 17, 2014*

**Physics**

Mass = 20kg?(Check for error). a = g = 9.8 m/s^2 F = m * g
*August 17, 2014*

**physics**

Vo = 84m/s[45o]. Dx = Vo^2*sin(2A)/g=84^2*sin90/9.8=720 m with zero wind. (720-630)/720 * 100% = 12.5% Decrease.
*August 17, 2014*

**math**

d^2 = X^2 + Y^2 = 4^2 + 5^2 = 41 d = 6.4 km. = Shortest distance to his home.
*August 17, 2014*

**Geometry**

One side = L units. 2nd side = 3L units. 3rd side = 15 units. 3L < 15 L < 5 L = 4 = Largest possible integer. 3L = 3*4 = 12. P = 4 + 12 + 15 = 31 = Max. possible perimeter.
*August 15, 2014*

**trig**

Angular velocity is usually given in rad/s., deg./s, or rev/min. So please check your INFO.
*August 15, 2014*

**Trigonometry**

12.4rev/ride * 3rides = 37.2 Revs. A = 37.2rev * 360Deg/rev = 13,392o = 233.6 Radians. Circumference=pi*2r = 3.14*36.6=114.92 m. d = 37.2rev * 114.92m/rev = 4275.2 m. traveled.
*August 15, 2014*

**Physics**

Or: d = -(10^2)/-0.6250 = 160 m. 160 - 150 = 10 m. Further.
*August 15, 2014*

**Physics**

Vo = 36km/h = 36,000m/3600s = 10 m/s. V = 9km/h = 9000m/3600s = 2.5 m/s. a = (V^2-Vo^2)/2d a = (2.5^2-10^2)/300 = -0.3125 m/s^2. d = (V^2-Vo^2)/2a d = (0-2.5^2)/-0.6250 = 10 m. Further.
*August 15, 2014*

**physics**

a=(V^2-Vo^2)/2d=(0-(20^2))/30=-13.3m/s^2
*August 14, 2014*

**phy**

M*g = 50 * 9.8 = 490 N. = Wt. of boy. T1*Cos(180-30) + T2*Cos60 = 0. -0.866T1 + 0.5T2 = 0. T2 = 1.732T1. T1*sin(180-30) + T2*sin60 = 490 0.5T1 + 0.866T2 = 490. Replace T2 with 1.732T1: 0.5T1 + 0.866*1.732T1 = 490. 2T1 = 490. T1 = 245 N. T2 = 1.732 * 245 = 424.3 N.
*August 13, 2014*

**High School Physics**

X = 10 m/s Y = 20 m/s V^2 = X^2 + Y^2 V^2 = 10^2 + 20^2 = 500 V = 22.4 m/s = Resultant velocity. a = (V-Vo)/t = (22.4-0)/t = 22.4/t m/s^2 d = 0.5*a*t^2 = 150 0.5*(22.4/t)*t^2 = 150 m (11.2/t)*t^2 = 150 11.2t = 150 t = 13.4 s.
*August 12, 2014*

**Math**

C = 75 + 5f. C is the dependent variable. It depends on the value of f.
*August 12, 2014*

**pHYSICS`**

m*g = 50kg * 9.8N/kg = 490 N. = Wt. of cart. Fk = u*mg = 0.2 * 490 = 98 N. = Force of kinetic friction. a=(V-Vo)/t = (0.90-0)/2.8 = 0.321 m/s^2/ F-Fk = m*a F - 98 = 50*0.321 = 16.07 F = 16.07+98 = 114.1 N.
*August 11, 2014*

**physics**

T = 50min * 1h/60min = 5/6 h. T = t1 + t2 = 5/6 h. d/(Vb-Vs) + d/(Vb+Vs) = T 8/(Vb-2.8) + 8/(Vb+2.8) = 5/6 LCD = (Vb-2.8)(Vb+2.8). (8(Vb+2.8)+8(Vb-2.8))/(Vb-2.8)(Vb+2.8)= 5/6. (8Vb+22.4+8Vb-22.4)/(Vb-2.8)(Vb+2.8)=5/6 16Vb/(Vb-2.8)(Vb+2.8) = 5/6 Cross multiply: 96Vb = 5(Vb-2.8...
*August 10, 2014*

**Math**

Eq1: 2r - 7s = -6 Eq2: 7r - 2s = 32 Multiply Eq1 by (-7) and Eq2 by 2; then add: -14r + 49s = 42 +14r - 4s = 64 Sum: 45s = 106 S = 2 16/45 = 106/45. In Eq1, replace s with 106/45: 2r - 7*(106/45) = -6 2r - 742/45 = -6 Multiply by 45: 90r - 742 = -270 90r = -270 + 742 = 472 r...
*August 10, 2014*

**Algebra**

15x(x+2) + 1(x+2) Factor out x+2: (x+2)(15x+1) = Final answer.
*August 10, 2014*

**physics**

a = (V-Vo)/t = (-4.4-6)/0.04=-260 m/s^2.
*August 10, 2014*

**physics**

I=(V1-V2)/(R1+R2) = (12-8)/(15+1)=
*August 10, 2014*

**PHYSICS**

d = 0.5a*t^2 = 10 m. 0.5a*(5.5)^2 = 10 15.125a = 10 a = 0.661 m/s^2. V = a*t = 0.661 * 5.5 = 3.636 m/s. d = Vo*t - o.5a*t^2 d=3.636*5.10 - 0.5*0.661*5.10^2=9.95 m.
*August 10, 2014*

**physics**

h = (V^2-Vo^2)/2g h = (0-(10^2)/-20 = 5.0 m.
*August 10, 2014*

**Alegbra**

a. (42,900-5100)/60 = b. Po = 42900 - 5100 = $37,800. P = Po*r*t/(1-(1+r)^-t) r = (2.5%/12)/100* = 0.00208 = Monthly % rate expressed as a decimal. t = 60 Months. P = (37,800*0.00208*60)/(1-1.00208^-60) = $40,251.02 Monthly Payments = P/t
*August 10, 2014*

**physics**

Vo = a*t = 17m/s^2 * 20s = 340 m/s. h1 = 0.5a*t^2 = 0.5*17*20^2 = 3400 m. = Ht. at which the engine shuts off. hmax = h1 + (V^2-Vo^2)/2g. hnax = 3400 + (0-(340^2)/-19.6 =9298 m. = 9.298 km above gnd. The rocket did not reach the required 12 km.
*August 9, 2014*

**physics**

T = 7days/week * 24h/day = 168 h. 0.2kW * 168h = 33.6 kWh Used. Cost = $0.14/kWh * 33.6kWh = $4.70
*August 9, 2014*

**physics**

D = Vo*t + 0.5a*t^2 D = 2*10 + 0.5*0.2*10^2 = 30 m.
*August 9, 2014*

**math**

B = # of boys in camp. 0.3B = # of boys from N.Y.S. 0.2 * 0.3B = 0.06B=# of boys from N.Y.C. (0.06B/B)*100% = 6% = Percentage of boys in camp from N.Y.C.
*August 8, 2014*

**math**

A = C pi*r^2 = pi*D pi*r^2 = pi*2r Divide both sides by pi*r r = 2 Inches. D = 2r = 2 * 2 = 4 Inches.
*August 8, 2014*

**Physics**

a. h = 12*s1n30 = 6 m. V^2 = Vo + 2g*h = 0 + 19.6*6 = 117.6 V = 10.84 m/s. b. m*g=83kg * 9.8N/kg = 813.4 N.=Wt. of the child. Fn = mg*cos30 = 813.4*cos30 = 704.4 N. = Normal = Force perpendicular to the slide. Fk = u*Fn = 0.30 * 704.4 = 211.3 N. = Force of kinetic friction. ...
*August 8, 2014*

**Physics**

d2 = d1+29 Vo2*t + 0.5a*t^2 = Vo1*t + 29 m 42t + 1.5t^2 = 28t + 29 1.5t^2 + 42t - 28t = 29 1,5t^2 + 14t = 29 1.5t^2 + 14t - 29 = 0 Use Quadratic Formula and get: t = 1.745 s. To pass the train. V = Vo + a*t = 42 + 3*1.745 = 47.24 m/s.
*August 8, 2014*

**Math 221**

See previous post: Thu, 8-7-14, 11:29PM.
*August 8, 2014*

**Math 221**

AC Method: 1. 2a^2 * 3a + 1 A*C = 2*1 = 2. 2+1 = 3 = B 2a^2 + (2a+a) + 1 Form 2 Binomials and factor: (2a^2+2a) + (a+1) 2a(a+1) + (a+1) (a+1)(2a+1). 2. 15x^2 + 31x + 2 A*C = 15*2 = 30 = 30*1. Sum = (30+1)=B. 15x^2 + (30x+x) + 2 (15x^2+30x) + (x+2) 15x(x+2) + (x+2) (x+2)(15x+1...
*August 7, 2014*

**algebra**

b = p-a-c
*August 7, 2014*

**math**

Shortest side = X. Other side = 2X. x + 2x > 11 3x > 11 X > 11/3 X > 3 2/3 X = 4 = Shortest possible length. 2X > 22/3 2X > 7 1/3 2X = 8.
*August 7, 2014*

**math**

Y yards * (3/8)jumps/yard = 3Y/8 Jumps.
*August 7, 2014*

**Physics**

Average Speed = (40+60)/2 = 50 km/h
*August 7, 2014*

**trigonometry**

X = 4 Ft/s Y = -2km/h = -2000m/3600s * 3.3Ft/m = -1.833 Ft/s Tan A = Y/X = -1.833/4 = -0.45825 A = -24.62o = 24.62o South of East. = 65.38o East of South = Direction. Magnitude = X/Cos A = 4/Cos(-24.62) = 4.4 Ft/s.
*August 7, 2014*

**trigonometry**

m*g = 200,000N. Fp = mg*sin A = 200,000*sin28 = 98,894 N = Force parallel with the incline = The pull on the rope.
*August 7, 2014*

**Physics**

Circumference=pi * 2r = 3.14 * 3=9.42 m. d = 0.5a*t^2 = 9.42 0.5*2.3*t^2 = 9.42 1.15t^2 = 9.42 t^2 = 8.19 t = 2.86 s.
*August 6, 2014*

**math**

3. Discount=((10.80-9.18)/10.80)*100%=15%. 4. Tax = (3.20/100)*Va = $1952 Solve for Va(assessed value). 7. Loan Amount = 7250-3000 = $4250 Cost = 7250 + 4250*(0.125/12)*9 = 8. Same procedure as #3. 9. Rate = ((4250-3910)/4250)*100% =
*August 6, 2014*

**algebra**

post it.
*August 4, 2014*

**Physics**

The horizontal component does not change
*August 3, 2014*

**Math**

h = 164t - 16t^2 = 400 Ft. -16t^2 + 164t = 400 -16t^2 + 164 - 400 = 0 Use Quadratic Formula and get: t = 4, and 6.25 seconds. Answer = 4 s. The rocket is falling when t = 6.25 s.
*August 2, 2014*

**Physics**

R = 450k Ohms. C = 49 uF 100%-75%=25% of the voltage remaining. x = t/RC = t/(450*49) = 4.54*10^-5t 1/e^x = 0.25 e^x = 4 x*Ln e = Ln 4 X = 1.386 x = 4.54*10^-5t = 1.386 t = 1.386/4.54*10^-5=30535 Milliseconds = 30.54 Seconds.
*August 1, 2014*

**physics**

10^-7J = 1 erg Multiply both sides by 10^7: 10^0J = 10^7 erg 1 J. = 10^7 erg.
*August 1, 2014*

**science**

Fr = 20N[270o] + 40N[45o] + 10[0o] = -20i + 40*cs45) + i40*sin45) + 10 = -20i + 28.28 + 28.28i + 10=38.28 + 8.28i Fr^2 = 38.28^2 + 8.28^2 = 1533.9 Fr = 39 N.
*July 31, 2014*

**physics**

a = (V-Vo)/t = (21.5-12.7)/3.45 =
*July 31, 2014*

**PHYSICS**

V = 300rev/min * 6.28rad/rev * 1min/60s = 31.4 rad/s. Circumference = pi*2r = 3.14 * 10=31.4 m. V = 300rev/min * 31.4m/rev * 1min/60s = 157 m/s. = Linear speed.
*July 30, 2014*

**physics**

F = m*a a = F/m = 3.0*10^4/0.06 = 5*10^5 m/s^2. a = (V-Vo)/t = 5*10^5 m/s^2 (75-0)/t = 5*10^5 5*10^5t = 75 t = 1.5*10^-4 s.
*July 30, 2014*

**physics**

m*g = 50kg * 9.8N./kg = 490 N. = Wt. of the box. Fp = 490*sin30 = 245 N. = Force parallel to the incine. Fn = 490*cos30 = 424.4 N. = Force perpendicular to the incline. Fk = u*Fn = 0.1 * 424.4 = 42.44 N. = Force of kinetic friction. At bottom of incline: KE + PE = mg*h - Fk*L ...
*July 30, 2014*

**Physics**

h = 32 m. A = 24.25o B = 18.2o Tan24.25 = h/X1 = 32/X1 X1*Tan24.25 = 32 X1 = 32/Tan24.25 = 71 m.=Hor. distance between boat A and the cliff. Tan18.2 = h/(X1+X2) = 32/(71+X2) (71+X2)*Tan18.2 = 32 71+X2 = 32/Tan18.2 = 97.33 X2 = 97.33-71 = 26.3 m=Distance between boat A and B.
*July 30, 2014*

**Physics**

m*g = 68kg * 9.8N./kg = 666.4 N. = Wt. of skier. Fp = 666.4*sin32 = 353.1 N. = Force parallel with incline. Fn = 666.4*cos32 = 565.1 N. = Normal = Force perpendicular to the incline. Fk = u*Fn = 0.05 * 565.1 = 28.26 N. = Force of kinetic friction. Fp-Fk = m*a a=(Fp-Fk)/m =(353...
*July 30, 2014*

**math**

12x = 3x+150 + 300 12x - 3x = 450 9x = 450 X = 50 Shirts.
*July 29, 2014*

**physics**

a = (V^2-(Vo^2))/2d =(0-(22^2))/8 = -60.5m/s^2. a = (V-Vo)/t t = (V-Vo)/a = (0-22)/-60.5 = 0.364 s.
*July 29, 2014*

**Physics**

The resistance of the voltmeter should be large compared to the resistance across which the voltage is being measured. If not, the voltmeter will act as an addition load on the circuit resulting in a lower reading. The voltmeter should be connected in parallel with the ...
*July 29, 2014*

**electric circuit**

Fuses are always connected in series with the circuit. Therefore, its' resistance should be small compared to the resistance of the circuit. The circuit of an Ammeter has a much lower resistance than a Voltmeter. So the fuse in the Ammeter has a higher current rating. ...
*July 29, 2014*

**physics**

1. 60s. * 1Wave/0.27s. = 222 Waves.
*July 28, 2014*

**PHYSICS**

V = Vo + a*t = 4.50 m/s. Vo + (-2.7)*3 = 4.5 Vo = 4.5 + 8.1 = 12.6 m/s. D = Vo*t + 0.5a*t^2 D = 12.6*3 - 0.5*2.7*3^2 = 25.7 m.
*July 28, 2014*

**Physics 2**

1. The step-down transformer reduces the primary voltage by a factor equal to the turns ratio. For instance, if the turns ratio was 4:1, the voltage across the secondary would be 1/4 of the primary voltage. In a step-up transformer with a turns-ratio of 1:4, the voltage across...
*July 28, 2014*

**physics**

d1 = d2 + 100m. 60t = 40t + 100 60t-40t = 100 20t = 100 t = 5 Hours.
*July 27, 2014*

**math**

Y > 8-5 Y > 3
*July 27, 2014*

**finance**

Program A: (5000/100,000)*100 = 5%Profit. Program B: (10,000/220,000)*100 = 4.55% Profit.
*July 27, 2014*

**Physics 2**

L = 1 mm to 1m. L = V/F F = V/L = 3*10^8/1*10^-3m = 3*10^11 Hz. F = 3*10^8/1m = 3*10^8 Hz.
*July 27, 2014*

**Physics 2**

L = V/F F = V/L = 300*10^6/300 = 10^6 Hz = 1 mHz
*July 27, 2014*

**physics**

A. Np/Ns = Vp/Vs = 120/12 = 10/1. Turns Ratio = 10:1 Ts = Tp/10 To find the number of turns on the secondary(Ts), we need to know the number of turns on the primary(Tp). B. 120 * I = 6 W. Solve for I. Fr = 1/(2pi*Sqrt(LC) Fr = 1(6.28*Sqrt( 0.40*30*10^-9) = 8.33 Million Hertz...
*July 27, 2014*

**science**

d = (V^2-Vo^2)/2a=(0-(20^2)/-8.6=46.51 m = Stopping distance. d = 55+22+5 = 82 m. = Distance through intersection. d = Vo*t + 0.5a*t^2 = 20*(3-0.25) + 0.5*2*(3-0.25)^2=62.6 m. Therefore, the driver must step on the brakes; because he or she cannot drive the required 82 meters ...
*July 27, 2014*

**physics**

Wt. of Cart=m*g = 250kg * 9.8N/kg=2450 N Fp = 2450*sin50 = 1877 N. = Force Parallel to the incline. Fn = 2450*cos50 = 1575 N. = Normal force Fk = u*Fn = 0.22 * 1575 = 346.5 N. = Force of kinetic friction. Fe-Fp-Fk = m*a Fe-1877-346.5 = m*0 = 0 Fe-2223 = 0 Fe = 2223 N. = Force ...
*July 27, 2014*

**trigonometry**

Smaller Pulley: V=15rev/12s * 6.28rad/rev = 7.85 rad/s Larger Pulley: V = (6cm/20cm) * 7.85 = 2.36 rad/s.
*July 26, 2014*