Wednesday

October 1, 2014

October 1, 2014

Total # Posts: 9,180

**Math**

Eq1: 3x - 9y = 3 Eq2: 6x - 3y = -24 In Eq1, solve for X: 3x = 9y + 3 X = 3y+1 In Eq2, replace X with 3y+1: 6(3y+1) - 3y = -24 18y+6 - 3y = -24 15y = -30 Y = -2. In Eq1, replace Y with-2: 3x-9*(-2) = 3 3x + 18 = 3 3x = -15 X = -5. Solution set: (-5,-2). Eq1: Y - X/2 = 6 Eq2: 2x...
*January 10, 2014*

**Inequalities help?**

1. m-7 < 6 m < 6+7 m < 13 2. p + 12 > 9 p > 9-12 p > -3 3. x - 5 => 9
*January 10, 2014*

**physical science**

V = 36m/s * 1mi/1600m * 3600s/h = 81mi/h
*January 9, 2014*

**Physics**

m1*V1-m2*V2 = 4.82*5.03-2.72*3.52=14.7 m*V = 14.7 V = 14.7/m = 14.7/(4.82+2.72) = 1.95 m/s
*January 9, 2014*

**Physics forces unit**

F = m*a If you know any 2 of the 3, you can calculate the third: m = F/a.
*January 9, 2014*

**Math**

X hrs in town. (1-X) hrs in country. 40x + 50(1-x) = 48 km 40x + 50-50x = 48 -10x = -2 X = 0.2 Hours in town 1-X = 1-0.2 = 0.8 hrs = 48 min. in the country.
*January 9, 2014*

**math**

d = (3/12) * 5.9*10^12 = 1.475*10^12 mi. You are correct.
*January 9, 2014*

**Math**

Total Cost = 10 + 32 = $42. CDs Bought = $42/$7 = 6.
*January 8, 2014*

**math**

2*1 + 48/10 + 5*100 = 2 + 4.8 + 500 = 506.8
*January 8, 2014*

**physics**

Impact = m1*V1-m2*V2=87*5-83*2.92=192.6 m*V = 192.6 V = 192.6/m = 192.6/(87+83) = 1.133 m/s
*January 8, 2014*

**physics**

See previous post.
*January 8, 2014*

**physics**

A. V = Vo + g*t = 0 500 - 9.8t = 0 9.8t = 500 Tr = 51.02 s. = Rise time = Time to reach max ht. B. T = Tr+Tf Tf = Tr = 51.02 s. = Fall time. T = 51.02 + 51.02 = 102.04 s. to reach gnd.
*January 8, 2014*

**trig**

d = 50mi * 5280Ft/m1 = 264,000 Ft. = 264K. (0,10k), (264k,20k). Tan A = (20k-10k)/(264k-0) = 0.037879 A = 2.2 Degrees.
*January 8, 2014*

**physics**

h(t) = ho - 0.5g.t^2 h(2) = 600 - 4.9*2^2 = 580.4 m. Above gnd. V(2) = Vo + g*t = 0 + 9.8*2 = 19.6 m/s. h(5) = 600 - 4.9*5^2 = 477.5 m. Above gnd. V(5) = 0 + 9.8*5 = 49 m/s. h(10) = 600 - 4.9*100 = 110 m. Above gnd. V(10) = 0 + 9.8*10 = 98 m/s.
*January 8, 2014*

**physics**

K = 30 + 273.15 = 303.15o Kelvin (2*10^-5/K)*303.15K*10cm = 0.06063 cm Increase in Length, each side. (0.06063)^3 = 2.2288*10^-4 cm^3 Increase in Volume.
*January 8, 2014*

**Physics**

Fg = m*g = 73 * 10 = 730 N. = Force of gravity. Fg-Fk = m*a 730-Fk = 73 * 5 = 365 N. -Fk = 365-730 = -365 Fk = 365 N. = Force of kinetic friction.
*January 7, 2014*

**physics**

Momentum = m1*V1 - m2*V2= 1*10-3*2=4 in the direction of m1. m*V = 4 V = 4/m = 4/(1+3) = 1 m/s. in the direction of m1.
*January 7, 2014*

**Math**

14. b. Debt = $25. 15. c. Debt < $25. 12. a. Debt > $25.
*January 7, 2014*

**physical Science**

Momentum = m*V = 200kg * 1m/s = 200. Momentum = m*V = 1kg * 200m/s = 200.
*January 7, 2014*

**physics**

240N/2cm^2 = 120N/cm^2
*January 6, 2014*

**physics**

240N/2cm^2 = 120N/cm^2 240N/40cm^2 = 6N/cm^2
*January 6, 2014*

**physics**

240N/2cm^2 = 120N/cm^2
*January 5, 2014*

**physics**

240N/40cm^2 = 6N/cm^2
*January 5, 2014*

**physics**

d = (150/50) * 15m = 135.
*January 5, 2014*

**physics**

d = d = (150/50)^2 * 15m = 135 m.
*January 5, 2014*

**math**

If L is known: 1. Plug-in the value of L. 2. Simplify the quantity under the radical. 3. Take the square root of the number under the radical. Example: L = 19.6 m. Solve for T. T = 2pi*sqrt((2/3)*L/g) T = 6.28*sqrt((2/3)*19.6/9.8) = 6.28*sqrt((2/3)*2) = 6.28*sqrt((4/3) = 6.28...
*January 1, 2014*

**Physics**

Does your textbook give the mass of the sled?
*January 1, 2014*

**Physics**

d = Vo*t + 0.5a*t^2 = 6 m. 0 + 0.5a*4^2 = 6 8a = 6 a = 0.75 m/s^2. Fp = m*g = 25kg * 9.8N/kg = 245 N. = Force of pickle. Fap-Fp-Fk = m*a Fap-245-3.8 = 25*0.75 Fap = 18.75+245+3.8 = 267.6 N. = Force applied. Work = Fap * d = 267.6 * 6 = 1605 Joules
*January 1, 2014*

**Math**

Correction: (30-X) Hrs. @ $12 per Hr. NOT (30-8).
*December 31, 2013*

**Math**

X Hrs @ $8 per hr. (30-8) Hrs @ $12 per hr. 8x + 12(30-x) = $268 8x + 360 - 12x = 268 -4x = 268-360 = -92 X = 23 Hrs. @ $8 per hr. 30-23 = 7 Hrs @ $12 per hr.
*December 31, 2013*

**Maths**

Reiny, you finished ahead of me; but i'm glad we got the same answer!
*December 30, 2013*

**Maths**

Mary = X Stamps. Wendy = X + 80 Jean = (X+80)-50 = X + 30 After Transactions: Mary= X + (X+80)/2 = (3X/2+40). Mary = 4/5(3X/2+40) = 6X/5+32 Wendy = (X+80)/2 Jean = (X+30)+3X/10+8=13X/10+38 Jean = (13X/10+38)=(X/2+40)+62 13X/10-X/2 = 62+40-38 = 64 13X/10-5X/10 = 64 8X/10 = 64 ...
*December 30, 2013*

**science**

A. Difference.
*December 30, 2013*

**Trigonometry**

I assumed you mean one surface is 576 cm^2. We have 6 equal surfaces. As = 6 * 576cm^2 = 3456 cm^2.
*December 29, 2013*

**physics**

F = 0.1kg * 9.8N/kg = 0.98N/kg = 0.98 N. K = F/d = 0.98N/0.04m = 24.5N/m.
*December 27, 2013*

**Physics**

Mass=540*10^3m^3 * 4.3*10^-3kg/m^3 = 2322 kg. Fb = m*g = 2322kg * 9.8N/kg = 22,756 N.
*December 24, 2013*

**physics**

V(co2) = (4500g/0.8g) * 1cm^3=5625 cm^3 V(co2)/Vex = 5625/7.1*10^3 = 0.79 = 79%.
*December 23, 2013*

**Environmental Science**

1.1kW = 1.1kJ/s T = 2.85*10^7kJ * 1s./1.1kJ * 1h/3600s * 1day/24h = 300 Days.
*December 22, 2013*

**physics**

Ws = m*g = 80kg * 9.8N/kg = 784 N. = Wt. of sled. Fp = 784*sin25 = 331.3 N. = Force parallel to the incline. Fn = 784*cos25 = 710.5 N. = Normal force = Force perpendicular to the incline. Fk = u*Fn = 0.7 * 710.5 = 497.4 N. = Force of kinetic friction. F-Fp-Fk = m*a F-331.3-497...
*December 21, 2013*

**math**

Rate = 300/6 = 50 Words/min. 2. $4.00/25 oz = $016/oz. $7.00/90oz = $0.08/0z. 3. d/12 = 96/8 8d = 12*96 = 1152 d = 1152/8 = $144
*December 21, 2013*

**physics**

Elastic limit.
*December 19, 2013*

**Science**

Yes, I use that trick when there are more conversions than we have here.
*December 19, 2013*

**Science**

V = 32km/h = 32000m/3600s = 8.89 m/s. 32km = 32,000 m. 1h = 3600s.
*December 19, 2013*

**math**

See previous post: 8:51 AM.
*December 19, 2013*

**physics**

V^2 = Vo^2 + 2a*d a = (V^2-V0^2)/2d a = (51^2-0)/150 = 17.34 m/s^2.
*December 18, 2013*

**math help**

(1*2*3*z)^2 = 144 (6z)^2 = 144 36z^2 = 144 z^2 = 4 Z = +-2.
*December 18, 2013*

**Physics**

See 3:47 AM post.
*December 18, 2013*

**Physics**

h = 50 m. Vo = 35m/s[50o] Xo = 35*cos50 = 22.50 m/s. Yo = 35*sin50 = 26.81 m/s. a. Y = Yo + g*t = 0 at max ht. 26.81 - 9.8t = 0 9.8t = 26.81 Tr = 26.81/9.8 = 2.74 s. = Rise time. hmax=ho + Yo*Tr - 0.5g*Tr^2 hmax=50+26.81*2.74 - 4.9*2.74^2=86.67 m. Above gnd. 0.5g*t^2 = 86.67 4...
*December 18, 2013*

**Physics**

1D. Cannot be determined, because we don't know the time. 2D. 5D.V = a*t = 2m/s^2 * 8s. = 16 m/s. 6B. V = Vo + g*t = 0 + 10*4 = 40 m/s. 7A. X = 100*cos 30 = 87 N. 8B.
*December 17, 2013*

**Physics**

F = (0.06m/1m) * 18N = 1.08 N. a = F/m = 1.08/7.66*10^-3 = 141 m/s^2. V^2 = Vo^2 + 2a>d V^2 = 0 + 282*0.06 = 16.92 V = 4.11 m/s. V^2 = 4.11^2 + 282*0.03 = 25.35 V = 5.03 m/s.
*December 17, 2013*

**Math**

L = (30/6) * 10Ft = 50 Ft
*December 16, 2013*

**physics- multiple choice**

1. True 2. 98 N, down. 3. Fn = m*g - 1000 = 600kg * 9.8-1000 = 5880 - 1000 = 4880 N.
*December 16, 2013*

**physics. HELP**

See previous post: Mon,12-16-13,7:15 PM.
*December 16, 2013*

**physics. HELP**

See previous post: Mon,12-16-13,7:11 PM.
*December 16, 2013*

**physics. HELP**

See previous post: Mon,12-16-13,7:07 PM.
*December 16, 2013*

**physics**

D = Xo * 1.8 = 30 m. Xo = 30/1.8 = 16.67 m/s=Hor. component of initial velocity. Y = Yo + g*Tr = 0 at max Ht. Yo - 9.8*(1.8/2) = 0 Yo - 8.82 = 0 Yo = 8.82 m/s = Ver. component of initial velocity. a. Vo^2=Xo^2 + Yo^2=16.67^2 + 8.82^2 = 355.7 Vo = 18.9 m/s = Initial velocity. b...
*December 16, 2013*

**physics**

Vo = 6 m/s[35o] = Initial velocity. Xo = 6*cos35 = 4.91 m/s.=Hor. component of initial velocity. Yo = 6*sin35 = 3.44 m/s=Ver. component of initial velocity. a. Y = Yo + g*t = 0 3.44 - 9.8t = 0 9.8t = 3.44 Tr = 3.44/9.8 = 0.3512 s. = Rise time. Tf = Tr = 0.3512 m/s = Fall time...
*December 16, 2013*

**physics**

D = Xo*t = 8.90 m Xo * 1.1 = 8.9 Xo = 8.9/1.1 = 8.09 m/s = Hor. component of initial velocity. Vo = Xo/cos A = 8.09/cos30=9.34 m/s[30o] = Initial velocity or take-off speed.
*December 16, 2013*

**physics**

d = V*t = 170 40*t = 170 t = 4.25 s. d2 = 0.5g*t^2 d2 = 4.9 * 4.25^2 = 88.5 m. = Vertical drop.
*December 16, 2013*

**phyics**

h = 1.5 m? h = 0.5g*t^2 = 1.5 m. Solve for t.
*December 16, 2013*

**math**

If the absolute value of a number is 21, the number can be positive or negative 21: 3x+12 => +-21 3x => +-21-12 X = (+-21-12)/3 = 3 or -11.
*December 16, 2013*

**algebra**

6j-5 < 2(3j-4) 6j-5 < 6j-8 6j-6j < -8+5 0 < -3. False.
*December 16, 2013*

**physics**

Net Force = Fap - Fk = 420-0.22*1420 = 107.6 N.
*December 16, 2013*

**physics**

d1 = 15m/s * 2s. = 30 m head start. d2 = 0.5a*t^2 = 30 + 15t 1*t^2 = 30 + 15t t^2 - 15t = 30 t^2 - 15t - 30 = 0 Use Quadratic Formula and get: t = 16.79 s.
*December 16, 2013*

**Physics**

V^2 = Vo^2 + 2g*d V^2 = 0 + 19.6*(58-25) = 646.8 V = 25.43 m/s.
*December 15, 2013*

**Mathematics**

Amt = 1.1*480 - 480 = 48
*December 14, 2013*

**Physics**

V=0.25rev/s * 6.28rad/rev = 1.57 rad/s. Note: The person's distance from the center does not affect the angular velocity. But the linear velocity decreases as the person walks toward the center.
*December 14, 2013*

**math**

h(n) = (100/90 * n h(27) = (100/9) * 27 = $300.
*December 14, 2013*

**Pre Calculus**

sec A*tan A/sin A = 1/cos A*sin A/cos A = sin A/cos^2 A/sin A = sin A/cos^2 A * 1/sin A = 1/cos^2 A.
*December 14, 2013*

**physics**

Circumference=pi*2r = 3.14 * 3 = 9.42 m. m = 15 kg. V = 5rad/s * 9.42m/6.28rad = 7.50 m/s. KE = 0.5m*V^2 = 0.5*15*7.50^2 = 421.9 J. Fp = mg*sinA = 15*9.8*sin15 = 38.05 N. = Force parallel to the incline. Fn = mg*cosA = 15*9.8*cos15 = 142 N. = Normal = Force perpendicular to ...
*December 14, 2013*

**Physics**

See previous post.
*December 11, 2013*

**Physics**

a. Wt.=m*g = 275kg * 9.8N/kg=2695 N = Wt of piano. Fp = 2695*sin30 = 1348 N. = Force parallel to incline. Fn = 2695*cos30 = 2334 N. = Normal = Force perpendicular to incline Fk = u*Fn = 0.40 * 2334 = 933.6 N. = Force of kinetic friction. Fex-Fp-Fk = m*a Fex-1348-933.6 = m*0 = ...
*December 11, 2013*

**Quick Math Help**

C = mx + b C = 5.5x + 10. The slope = 5.5. So the cost would decrease.
*December 11, 2013*

**Math**

2bags * 8.5Lbs/bag = 17 Lbs of mints. 17/(1/12) = 17 * 12/1=204 Place setting. 256-204 = 52 Short.
*December 11, 2013*

**Physics**

F = ((Vs+Vr)/(Vs-Vd))*Fd = 2355 Hz. ((343+0)/(343-Vd))*2000 = 2355 ((343)/(343-Vd))*2000 = 2355 686000/(343-Vd) = 2355 2355(343-Vd) = 686000 343-Vd = 291.3 -Vd = 291.3-343 = -51.7 Vd = 51.7 m/s = Velocity of the diver.
*December 11, 2013*

**Physics**

Vo = 9.37km/h = 9370m/3600s = 2.60 m/s hmax = (V^2-Vo^2)/2g = (0-2.60^2)/19.6 = 0.345 m.
*December 11, 2013*

**GEOMETRY PLZ HELP!**

See previous post: Tue,12-10-13,8:35 PM.
*December 10, 2013*

**Pre-calc**

Logx 16 = -2. x^-2 = 16 1/x^2 = 16 16x^2 = 1 x^2 = 1/16 x = 1/4.
*December 10, 2013*

**geometry**

c^2 = a^2 + b^2 c^2 = 6^2 + 6^2 = 72 c = 8.49 Ft. = 101.82 In. 101.82/4 = 25.46 or 25 Wall panels. 0.46 * 4 = 1.8 Inches. .
*December 10, 2013*

**pre calculus**

X^2 - 3X - 7 = 0 This Eq cannot be factored. Use the Quadratic Formula: X = (-B +- sqrt(B^2-4AC))/2A X = (3 +- Sqrt(9+28))/2 X = (3 +- 6.08)/2 = 4.54, and -1.54.
*December 10, 2013*

**college intermediate algebra**

1st person: X min. 2nd person: (X+20) min. X*(X+20)/(X+X+20) = 24 min. (X^2+20X)/(2X+20) = 24 X^2+20X = 48X+480 X^2-28X-480 = 0 Use Quadratic formula and get: X = 40 min. X+20 = 60 min.
*December 10, 2013*

**Ap Physics 1**

See previous post: Tue,12-10-13,9:37 AM.
*December 10, 2013*

**Ap Physics 1**

b. Fap-2100 = m*a Fap-2100 = 71,905*0.21 Fap-2100 = 15,100 Fap = 17,200 N.
*December 10, 2013*

**Ap Physics 1**

Fap = 17,500 N. = Force applied. Fk = 2400 N. = Force of kinetic friction a. m=(Fap-Fk)/a m = (17,500-2400)/0.21=71,905 kg.
*December 10, 2013*

**Physics**

L = V/F = 5.9*10^-4 m. V/2.60 = 5.9*10^-4 V = 1.534*10^-3 m/uS. d=1.534*10^-3m/uS * 11/2*!0^6uS=8440 m.
*December 10, 2013*

**science**

Amt. left = (1/2)^6 = (1/2)^3*(1/2)^3 =1/8 * 1/8 = 1/64 (1/64) * 100% = 1.65%
*December 9, 2013*

**physics**

See previous 5:35 PM post.
*December 9, 2013*

**physics**

See previous 5:35 PM post.
*December 9, 2013*

**physics**

V^2 = Vo^2 + 2g*h V^2 = 0 + 19.6*150 = 2,940 V = 54.2 m/s.
*December 9, 2013*

**Physics**

Overflow = The increase in vol. Same procedure as previous problem.
*December 8, 2013*

**Physics**

Increase = a(T-To)Vo = 1.63*10^-4(20-15)0.3=2.45*10^-4 m^3.
*December 8, 2013*

**Physics**

Overflow = a(T-To)Vo Overflow=3.7*10^-4(90-20)100=2.59 cm^3
*December 8, 2013*

**Math**

1. 0.5^3x-2 = 14 0.5^3x = 14+2 = 16 Take Log of both sides: 3x*Log 0.5 = Log 16 Divide both sides by Log 0.5: 3x = Log 16/Log0.5 = -4 Divide both sides by 3: X = -4/3 2. Log(x-1)-Log x = Log(x-3) Log((x-1)/x) = Log(x-3) B. f(x) = (x+2)/x; g(x) = 7/(x-5) a. F(g(x)) = (7/(x-5)+2...
*December 8, 2013*

**Physics**

Fc = m*g = 4000kg * 9.8N/kg = 39,200 N. = Force of car. Fp = 39200*sin19.6 = 13,150 N. = Force parallel to the slope. Fn = 39200*cos19.6 = 36,929 N. = Normal Force = Force perpendicular to the slope Fk = 4,000 N. = Force of kinetic friction. a=(Fp-Fk)/m a = (13150-4000)/4000=2...
*December 6, 2013*

**Dyanamics**

1. A = 32km/h[135o],CCW Xa = 32*cos135 = -22.63 km/h Ya = 32*sin135 = 22.63 km/h B = 24km/h[220o],CCW Xb = 24*cos220 = -18.39 km/h Yb = 24*sin220 = -15.43 km/h Xa and Xb are in same direction. So we subtract: Xc=Xb-Xa = -18.39 - (-22.63)=4.24 km/h Yc = Yb+Ya = -15.43 + 22.63...
*December 6, 2013*

**physics**

F = m*a = 9 * 3 = 27 N.
*December 6, 2013*

**physics**

To = 9C/5 + 32 = 9*35/5 + 32 = 95oF. T = 9*(-12)/5 + 32 = 10.4oF. a max = 7.9*10^-6/oF. Change = a*(T-To)ho 7.9*10^-6*(10.4-95)*170 = -11.36 cm. Change = 11.36 cm decrease
*December 6, 2013*

**physics**

Vo = 16m/s[20o] Yo = 16*sin20 = 5.47 m/s. Y = Yo + g*t = 0 At max. Ht. 5.47 - 9.8t = 0 9.8t = 5.47 Tr = 0.558 s. = Rise time Tf = Tr = 0.558 s. = Fall time. T = Tr+Tf = 0.558 + 0.558 = 1.12 s.
*December 6, 2013*

**Geometry**

As = 2W*h + 2L*W + 2L*h = 214 m^2. 70 + 14L + 10L = 214 24L = 144 L = 6 m. V = L*W*h = 6 * 7 * 5 = 210 m^3.
*December 6, 2013*

**physics**

A = 6m[30o[ Y = 6*sin30 = 3m = North Component. B = 7m[132o], CCW. Y = 7*sin132 = 5,20 m. = North component. The component along the north direction of person A is smaller.
*December 6, 2013*

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