Friday

September 4, 2015
Total # Posts: 10,949

**physics**

Correction: 1st Ball: d1 = Vo*t + 0.5g*t^2 d1 = 0 + 4.9*2^2 = 19.6 m. in 2 s. V = Vo + g*t = 0 + 9.8*2 = 19.6 m/s. 2nd Ball: d2 = d + 19.6 m. Vo*t + 0.5g*t^2 = V*t + 0.5g*t^2 + 19.6 Vo*t - V*t + 0.5g*t^2-0.5g*t^2 = 19.6 Vo*t - V*t = 19.6 30t- 19.6t = 19.6 10.4t = 19.6 t = 1.88...
*August 31, 2014*

**physics**

1st Ball: d1 = Vo*t + 0.5g*t^2 d1 = 0 + 4.9*2^2 = 19.6 m in 2 seconds 2nd Ball: d2 = d1 + 19.6 m Vo*t + 0.5g*t^2 = 4.9t^2 + 19.6 30t + 4.9t^2 - 4.9t^2 = 19.6 30t = 19.6 t = 0.6533 s. To overtake the 1st ball.
*August 31, 2014*

**Physics**

C = 8,420.10/2.9 =
*August 31, 2014*

**business**

P = Po*(1+r)n Po = $1,000 r = (16%/2)/100% = 0.08 = Semi-annual % rate. n = 10yrs. * 2comp./yr = 20 Compounding periods. P = 1000(1.08)^20 = $4660.96 I = P-Po
*August 30, 2014*

**Physical Science**

Wood will float in a liquid if it's density is less than the density of the liquid.
*August 30, 2014*

**physics**

1uA = 1*10^-6A = 1*10^-3 mA.
*August 29, 2014*

**Physical Science**

Wt. = m*g = 4.82kg * 9.8N/kg = 47.24 N. a = F/m = 10/4.82
*August 29, 2014*

**Physics**

a. Tr = -Vo/g = -40/9.8 = 4.08 s. = Rise time. b. h = ho + (V^2-Vo^2)/2g h = 80 + (0-(40^2))/-19.6 = 161.6 m. Above gnd. c. V = Vo + g*t = 40 - 9.8*2 = 20.4 m/s. d. V*2 = Vo^2 + 2g*(h-20) V^2 = 0 + 19.6*(161.6-20) = 2775.36 V = 52.7 m/s. e. h = 4.9t^2 = 161.6 m. 4.9*t^2 = 161....
*August 27, 2014*

**Physics**

a. Correct. b. Correct. c. Correct. d. h = ho-(V^2-Vo^2)/2g h = 80-(30^2-4^2)/19.6 = 34.9 m Or V = Vo + gt = 30 m/s. V = 4 + 9.8t = 30 9.8t = 26 t = 2.653 s. h = ho - (Vo*t + 0.5g*t^2) h = 80-4*2.653 + 4.9*2.653^2 = 34.9 m
*August 27, 2014*

**Matt**

X = The # of boys. X+250 = The # of girls x/(X+250) = 2/7 7x = 2x + 500 5x = 500 X = 100 Boys. X+250 = 100+250 = 350 Girls.
*August 27, 2014*

**math**

(3x-2)^2(3x-2)-(4x+5)^2 = (9x^2-12x+4)(3x-2)-(16x^2+40x+25) = 27x^3-36x^2+12x-18x^2+24x-8-16x^2-40x-25 = 27x^3-70x^2-4x-33.
*August 27, 2014*

**math**

The cable is the hyp. of a rt. triangle, and the ht. of the balloon is the ver. side. h = 842*sin65 = 763.1 Ft. = Ht. of the balloon. Tan4 = h/BC BC = h/Tan4 = 763.1/Tan4 = 10,913 Ft = Distance from the target to point C.
*August 27, 2014*

**algebra**

Investment @ 7% = Po Investment @ 6% = 32,000-Po Po*r*t + (32000-Po)*r*t = 2,050 Po*0.07*1 + (32000-Po)*0.06*1 = 2050 0.07Po + 1920 - 0.06Po = 2050 0.01Po = 2050-1920 = 130 Po = $13000 @ 7%. 32,000-13000 = $19,000 @ 6%.
*August 27, 2014*

**math**

Correct!
*August 27, 2014*

**Physics**

See previous post: Tue,8-26-14,10:29 PM.
*August 27, 2014*

**Math**

610EUR/800AUD * 1USD/0.753EUR = 1.0126 USD/1AUD Note: EUR in the Equation cancels.
*August 27, 2014*

**Physics**

V = 34[20o] + 28[53.1o] X = 34*cos20 + 28*cos53.1 = 48.75 Units. Y = 34*sin20 + 28*sin53.1 = 34.03 Units. V^2=X^2 + Y^2 = 48.75^2 + 34.03^2=3535. V = 59.5 Units.
*August 26, 2014*

**math**

20,000,000+484,000+100+60+3.
*August 26, 2014*

**Math**

2,5. LCM = 10. 5,10. LCM = 10.
*August 26, 2014*

**math**

(2-x)/8 = 3/4 Multiply both sides by 8: 2-x = 6 -x = 6-2 = 4 X = -4. Or 2 - x/8 = 3/4 Multiply both sides by 8: 16-x = 6 -x = 6-16 = -10 X = 10.
*August 26, 2014*

**Math**

Kendall: X in. tall. Rachel: 2x in. tall. Rich: (2x+3) in tall. Brian: (2x+3)-1 = 74 in. tall. (2x+3)-1 = 74 2x + 2 = 74 2x = 72 X = 36 in. = Kendall's ht.
*August 26, 2014*

**science**

100.0g of 4.0c water is heated until its temperature is 37c. if the specific heat of water is 4.18 j/g c, calculate the amount of heat energy needed to cause this rise in temperature.
*August 25, 2014*

**Physics**

Range = 15,000 Meters? Range = Vo^2*sin(2A)/g = 15,000 m. Vo^2*sin(60)/9.8 = 15000 0.08837Vo^2 = 15000 Vo^2 = 169,741 Vo = 412 m/s.
*August 25, 2014*

**physics**

Work = Fx*d = 180*cos20 * 5 = 845.7 J. I don't understand what you are saying in the last paragraph.
*August 25, 2014*

**Math**

0.06C = 0.30 C = $5.00
*August 25, 2014*

**math**

a. 120I = 100 W. I = 0.833A R = V/I = 120/0.833 = 144 Ohms. b. Same procedure as a. c. Same procedure as a. a. Imax = V/(72+0) = 115/(72+0) = 1.60A Imin = 115/(72+88) = 0.719A b. P = V^2/(Rc+R) = 90 W. 115^2/(72+R) = 90 90*(72+R) = 115^2 72+R = 146.94 R = 146.94-72 = 74.94 ...
*August 24, 2014*

**Algebra 2**

T1*T2/(T1+T2) = 3*2/(3+2) = 1.2 h/Lawn. T = 1.2h/Lawn * 12Lawns = 14.4 Hours Note: 1.2h = 6/5 h = Time to do 1 Lawn.
*August 24, 2014*

**physics**

X = 200 km. Y = -600 km. d^2=X^2 + Y^2=200^2 + (-600)^2=400,000 d = 632 km.
*August 24, 2014*

**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*