Tuesday

February 21, 2017
Total # Posts: 13,190

**Math**

See previous post: Wed, 1-25-17, 8:22 P.M.

*January 25, 2017*

**physics**

Disp. = -34i + 117 + 64.5i + 28.5 = 145.5 + 30.5i. Magnitude = sqrt(145.5^2+30.5^2) =

*January 25, 2017*

**Math**

Wed.: d = r*t1 = 50mi/h * (43/60)h = 35.83 mi. Thu.: t2 = d/r = 35.83/68 = 0.527 h. = 31.6 min. t1-t2 = 43-31.6 = 11.4 min = Time saved.

*January 25, 2017*

**Physics**

40m/1min = 40m/60s = 0.667 m/s.

*January 25, 2017*

**Math**

5/20 = 1/4. A. = 1/4. D. 25/10 = 1/4.

*January 24, 2017*

**physics**

The positive and negative plates of a parallel-plate capacitor have an area of 1.05 cm by 1.05 cm. Their surface charge densities are +1.00×10-6 C/m2 and -1.00×10-6 C/m2, respectively. A proton moving parallel to the plates enters the middle of the space between ...

*January 24, 2017*

**science**

The system is in equilibrium: 30o W. of N. = 120o CCW. T1*Cos120 = -T2*Cos60. T1 = T2. T1*sin120 + T2*sin60 = -(-10) = 10. T2*sin120 + T2*sin60 = 10, 0.866T2 + 0.866T2 = 10, T2 = 5.77 N. T1 = T2 = 5.77 B.

*January 24, 2017*

**applied mechanics**

Vo = 72000m/3600s = 20 m/s. V = Vo + a*t = 0. 20 + a*5 = 0, a = -4 m/s^2. V^2 = Vo + 2a*d. V = 0, Vo = 20 m/s, a = -4 m/s^2, d = ?.

*January 24, 2017*

**Algebra**

K = (M2-M1)/(d2-d1) = (30-12)/(18-15) = 6 kg/cm . d = (12kg/6kg) * 1cm = 2 cm. L + 2 = 15, L = 13 cm.

*January 24, 2017*

**Science**

F = m*g in Newtons(N). Work = F*d in Joules.

*January 24, 2017*

**Math**

Assuming simple interest: P = Po + I = Po + Po*r*t. P = 6500 + 6500*0.09*4 = 6500 + 2340 = $8840 = Total amt. paid. I = P=Po =

*January 24, 2017*

**Math**

a. d = r*t. b. t = d/t. Eq1: t1 + t2 = 4 1/3 h. = 13/3 h. Eq2: 60t1 + 90t2 = 350 km. Solve the 2 Eqs simultaneously: -60t1 - 60t2 = -260 +60t1 + 90t2 = 350 sum: 30t2 = 90, t2 = 3 h. t1 + 3 = 13/3, t1 = 4/3 = 1 1/3 h. d1 = 60 * 4/3 = d2 = 90 * 3 =-

*January 24, 2017*

**Geometry**

As = 2pir^2 + pi*2r*h. As = (6.28*8^2) + (3.14*16*24) = 1608 m^2.

*January 23, 2017*

**Math**

a. 3:05, and 3:10. b. 5:00, and 6:05. c. 10:00, and 11:00.

*January 23, 2017*

**Maths**

c = X cm. a = x+20 cm. b = x+20 + 50 cm. a + b + c = 270. x+20 + x+20+50 + x = 270. X = ?. b = x+20+50.

*January 23, 2017*

**physics**

T = 2pi*sqrt(L/g). pi = 3.14., L = 1.25 m., g = 9.8 m/s^2.

*January 23, 2017*

**math**

a = b. x+2y = -2x+6y+1. Eq1: 3x-4y = 1. a + b + c = 28. x+2y -2x+6y+1 + 4y = 28. Eq2: -x+12y = 27. Add Eq1 and Eq2, solve for X, and Y: +3x - 4y = 1 -3x + 36y = 81(3*Eq2). sum: +32y = 82, Y = 41/16. In Eq1, replace Y with 41/16, and solve for X: 3x - 4*41/16 = 1, X = 15/4. X...

*January 22, 2017*

**Mathematics**

1. P1 = Po + Po*r*t. P1 = 12,500 + 12,500*0.12*3 = 2. P2 = Po(1+r)^n. Po = 12,500, r = 0.10. n = 1comp./yr. * 3yrs. = 3 compounding periods. P1-P2 =

*January 22, 2017*

**math**

Eq1: 4x + 2y = -2. m1 = -A/B = -4/2 = -2. m2 = m1 = -2. P2 = (-5,-7). Y = mx + b = -7, -2x + b = -7, b = -7+2x = -7 + 2(-5) = -17. Eq2:Y = -2x - 17.

*January 20, 2017*

**physical science**

Fr = -300 + 150 = -150 N. = 150 N. to the left.

*January 20, 2017*

**math**

C = pi*D = 3.14 * 25 = 78.5 in. 5,280ft/mi * 12in/ft. * 360o/78.5in * 295mi =

*January 19, 2017*

**Math**

The altitude(ht.) bisects the vertical angle and the base: 118/2 = 59o. Tan(90-59) = h/5. h = ?.

*January 19, 2017*

**Math**

Concentration = 6*120mg/60mls =

*January 18, 2017*

**Physical Science.**

Displacement is the straight-line distance from the end point to the starting point. The path traveled might not be a straight line. Displacement =< Distance traveled.

*January 18, 2017*

**Algebra**

T = T1*T2/(T1+T2) = 16*15/(16+15) =

*January 18, 2017*

**math**

0nes place = 9. tens place = X. hundreds place = X+1. x + x+1 = 11. X = 5. 659 blocks.

*January 18, 2017*

**Algebra 2**

2 People: 60boxes/10min . = 6 boxes/min. 6 People: (6/2) * 6 = 18 boxes/min. T = 120boxes * 1min/18boxes = 6.67 min.

*January 18, 2017*

**dynamics**

V1 = 400m/20s = 20 m/s. V2 = 400m/30s = 13.33 m/s. a = (V2-V1)/(T2-T1) = (13.33-20)/(30-20) = -0.667 m/s^2. V2 = V1 + 2a*d. 13.33 = 20 - 2*0.667*d. d = ?.

*January 18, 2017*

**physics**

a. M1*V1 + M2*V2 = 2.9*5.4 - 1.5*1.4 = 13.6

*January 17, 2017*

**physics**

V = Vo + a*t. -1.33 = 0 + a*0.96, a = -1.33/0.96 = -1.39 m/s^2. F = M*a = 53.8 * (-1.39) = -74.5 N.

*January 17, 2017*

**math**

a. At =8*11= 88 in^2 = Total area. Ac = pi*r^2 = 3.14 * 1.5^2 = 7.07 in^2. = Area of each circle. As = 3 * 3 = 9 in^2. = Area of a 3 in square in which the circle can be inscribed. At/As = 88/9 = 9.78 or 9 = The number of squares = the number of circles that can be cut. b. 9Ac...

*January 17, 2017*

**Grade 6, percentage**

At beginning of year: X members in art club. 0.4X boys. 0.6X girls. In middle of year: 0.75 * 0.6X = 0.45X girls remaining. 0.4X+8 boys remains. 0.45x + 0.4x+8 = 42. X = 40 At beginning of year.

*January 17, 2017*

**maths**

Insufficient INFO.

*January 15, 2017*

**MATH**

200paces/4sides = 50 paces/side. 50paces/side * 40cm/pace = 2000 cm/side.

*January 15, 2017*

**Math- fractions**

So, we find a common denominator for the two fractions: 2/3 = 8/12, and 3/4 = 9/12.

*January 15, 2017*

**math**

I = Po*r*t = 8000*0.07*5 =

*January 12, 2017*

**Grade 6, percentage**

X members at first. 0.8 * x = 0.8x Male. x - 0.8x = 0.2x Female. After 450 members left: 0.75*0.8x + 0.5*0.2x = x-450. 0.6x + 0.1x - x = -450, X = 1500.

*January 12, 2017*

**Physics**

64.8o W of N = 154.8o CCW. 22.4o W of N. = 112.4o CCW. M1*V1 + M2*V2 = = M1*V3 + M2*V4. 0.4*3.57m/s[154.8o] + 0.45*5.46m/s[90o] = 0.4*4.28m/s[112.4o] + 0.45*V4. 1.43m/s[154.8] + 2.46m/s[90o] = 1.71m/s[112.4] + 045V4, -1.29+0.609i + 2.46i = -0.652+1.58i + 0.45V4, -1.29 + 3.07i...

*January 11, 2017*

**Physics**

L = V*T. 1.3 = 2.5*T, T = ?

*January 11, 2017*

**algebra**

Divide numerator and denominator by 5: (x-1)/(2x^2-5x+3). Factor the denominator: A*C = 2*3 = 6 = (-2)*(-3), 2x^2 - (2x+3x) + 3 = 0, (2x^2-2x) - (3x-3) = 0, 2x(x-1) - 3(x-1) = 0, (x-1)(2x-3) = 0, (x-1)/(x-1)(2x-3) = 1/(2x-3).

*January 11, 2017*

**maths**

Option 1: P = Po + Po*r*t. P = 12,000 + 12,000*(0.08/12)*9 = 12,000 + 720 = $12,720. I = $720. Option 2: Ar = Ab-Ab*r*t. Ar = 12,000-12,000*(0.07/12)*9 = 12,000 - 630 = $11,370 = Amt. received. I = $630. Gary should choose Option 2.

*January 11, 2017*

**Physics**

See previous post: Wed, 1-11-17, 12:49 PM.

*January 11, 2017*

**Physics**

F = M*g = (80+20)*9.8 = Work = F*d.

*January 11, 2017*

**Physics**

d = 0.5g*t^2 = 4.9*1^2 = 4.9 m.

*January 11, 2017*

**Trig/PreCalc**

Vr = 425mph[160o] + 75mph[200o]. X = 425*cos160+75*cos200 = -470 mph. Y = 425*sin160+75*sin200 = 120 mph. Tan A = Y/X = 120/-470 = -0.25532. A = -14.3o. = 14.3o N. of W. = The direction. Vr = -470/-Cos14.3 = 485 mph. = Resultant speed.

*January 10, 2017*

**Science**

F=M1*a1. M1 = F/a1 = 400/2 = 200 kg. M2 = F/a2 = 400/13 = 30.8 kg. a = F/(M1+M2).

*January 10, 2017*

**Physics**

The two numbers cannot be added directly, because they are 90o out of phase: V = 300 + 400i. You only want the magnitude: V = sqrt(300^2+400^2) = 500 m/s.

*January 10, 2017*

**Physics**

M*g = 30 * 9.8 = 294 N. Fp = 294*sin30 = 147 N. = Force parallel with slide. Fn = 294*cos30 = 254.6 N. = Force perpendicular to the ride = Normal. Fk = u*Fn = 0.15 * 254.6 = 38.2 N. = Force of kinetic friction. Fap = 200 N. = Force applied. Fap-Fp-Fk = M*a. 200-147-38.2 = 30*a...

*January 10, 2017*

**Physics**

a,b. M1*V1 + M2*V2 = M1*V3 + M2*V4. 1*5 + 1*0 = 1*4[37o] + 1*V4. 5 = 4[37o] + V4, V4 = 5-4[37O], V4 = 5-4*Cos37-4*sin37 = 5-3.19-2.41i = 1.81 - 2.41i = 3.01m/s[-53.1o] = 3.01m/s[53.1o] S. of E. = Velocity and Direction. c. A1+A2 = 37 + 53.1 = 90.1o.

*January 9, 2017*

**Math**

D. 12/15 = 4/5, 30/50 = 3/5. The ratios must be equal to form a true proportion.

*January 8, 2017*

**physics**

M*g = 225, M = 225/g = 225/9.8 = 23 kg. F = M*a, a = F/M = 14.5/23 = 0.630 m/s^2.

*January 8, 2017*

**physics**

The system is in equilibrium: T1*sin15.4 + T2*sin A = +253. 459*sin15.4 + T2*sin A = 253, 121.9 + T2*sin A = 253. T2 = (253-121.9)/sin A = 131.1/sin A. -T1*Cos15.4 + T2*Cos A = 0, -459*Cos15.4 + T2*Cos A = 0. T2*Cos A = 459*Cos15.4 = 442.5, (131.1/sin A)Cos A = 442.5, 131.1*...

*January 8, 2017*

**Science**

M/W.

*January 8, 2017*

**Physics**

Density = 100g/150cm^3 = 0.667 g/cm^3.

*January 8, 2017*

**Physics**

Vb = 0.85 * 250 = 212.5 cm^3 = Vol. below surface. = Vol. of water displaced. V*D = 212.5cm^3 * 1g/cm^3 = 212.5 grams of water displaced. Upthrust = M*g = 0.2125 * 9.8 = 2.08 N.

*January 8, 2017*

**Math**

8/(2/3) = 8 * 3/2 = 12. pieces.

*January 8, 2017*

**Science(physics)**

V = (V1+V2)/2 = (15+25)/2 = 20 km/h.

*January 8, 2017*

**Science(physics)**

A boy while driving to his school covers at the average speed of 15km/h.On his return trip along the same route, covers at the average speed of 25km/h due to less traffic.What is the average speed for the whole trip

*January 8, 2017*

**Finance**

P = Po(1+r)^n = 83,190. r = APR expressed as a decimal. n = The number of compounding periods. 30,000(1+r)^9 = 83,190. (1+r)^9 = 83,190/30,000 = 2.773, 9*Log(1+r) = Log2.773, Log(1+r) = Log2.773/9 = 0.0492, 1+r = 10^(0.0492) = 1.12, r = 1.12-1 = 0.12 = 12%.

*January 6, 2017*

**physics**

M*g = Wt. of car. a. Fn = Mg*Cos17 = 0.956Mg. Fn/Mg = 0.956Mg/Mg = 0.956. b. Fn = Mg*Cos30 = 0.866Mg. Fn/Mg = 0.866Mg/Mg = 0.866.

*January 5, 2017*

**physics**

Car A: 0.5a*Ta^2 = 400 m. 0.5*11*t^2 = 400. Ta = ?. Car B: 0.5*11.8*Tb^2 = 400. Tb = ?. b. T = Ta-Tb.

*January 5, 2017*

**math**

Y = 1.0 + 0.06*180 Calories/min.

*January 5, 2017*

**College Physics**

Find?. F1+F2= M*a. Eq1: F1+F2 = 5.75 * 0.979 = 5.63 N. F1-F2 = M*a. Eq2: F1-F2 = 5.75*0.639 = 3.67 N. F1+F2 = 5.63 F1-F2 = 3.67 Sum: 2F1 = 9.30, F1 = 4.65 N. F1-F2 = 3.67, 4.65-F2 = 3.67, F2 = 0.98 N.

*January 5, 2017*

**Science**

Range = Vo^2*sin(2A)/g. Vo = 100 m/s, A = 45o, g = 9.8 m/s^2.

*January 5, 2017*

**physics**

a. 9.8 m/s^2. b. V*2 = Vo^2 + 2g*d. V = 0, Vo = 20 m/s, g = -9.8 m/s^2, d = ?. c. V = Vo + g*t. V= 0, Vo = 20 m/s, g = -9.8 m/s^2, t = ?. d. T = 2*t(part c).

*January 5, 2017*

**Math**

5/6 = 10/12 = 15/18 = 20/24 = 25/30.

*January 5, 2017*

**Science**

P = F*d/t = 8000*75/30 J/s = Watts.

*January 4, 2017*

**Math**

V = Vo + a*t. V = 46.6 m/s, Vo = 0, t = 6.82 s, a = ?. F = M*a.

*January 4, 2017*

**Maths**

L*W = 680 m^2. L*20 = 680, L = 34 m. 2L + W = 2*34 + 20 = 88 m. needed.

*January 4, 2017*

**Math**

(17-(-28))/(14-5) = 5deg./h. T = 5deg./h * (6-5)h = 5 Degrees.

*January 4, 2017*

**Physics**

3a. L = V/F = 3*10*8/8.85*10^7 = 3.39 m = Wavelength. La = 1/4 * 3.39 = 0.85 m. = Length of antenna. b. L = V/F = 3*10^8/5.3*10^5 = Wavelength. 1/4 * wavelength = Length of antenna. 4. L = V/F = 347/1566 = 0.222 M.

*January 3, 2017*

**Physics, math, algebra**

V = Vo + a*t. V = 42300m/3600s = 11.75 m/s. Vo = 0, a = 5.60 m/s^2, t = ?.

*January 3, 2017*

**Math**

x/2 = -9/14. X = -18/14 = -9/7. Eq:(-9/7)/2 = -9/14.

*January 3, 2017*

**Physics**

a. F1 = 110-4 = 106 Hz. = The difference freq. F2 = 110+4 = 114 Hz = The sum freq. b. Adjust strings until the notes cannot be heard.

*January 3, 2017*

**Doppler Effect**

Fo = (Vs+Vo)/(Vs-Vc) * Fc. Fo = (330+0)/(330-16) * 320 =

*January 3, 2017*

**Doppler Effect**

a. Moving away. b. Fo=(Vs-Vo)/(Vs+Vb) * Fb = 80. (343-0)/(343+Vb) * 85 = 80, 343/(343+Vb) = 80/85 = 0.941 322.8+0.941Vb = 343, Vb = 21.4 m/s. b.

*January 3, 2017*

**Engineering**

(y-2)^3 = (y+2)^3. (y-2)^2(y-2) = (y+2)^2(y+2). (y^2-4y+4)(y-2) = (y^2+4y+4)(y+2) y^3-4y^2+4y-2y^2+8y-8=y^3+4y^2+4y+2y^2+8y+8, -6y^2+12y-8 = 6y^2+12y+8, -12y^2 = 16, Y = 1.155i. No real solution, because y-2 cannot equal y+2.

*January 2, 2017*

**Maths**

V = Vo - Vo*r*t. V = 100,000 - 100,000*0.05*2 = 90,000.

*January 1, 2017*

**Maths**

V = Vo - Vo*r*t. V = 100,000 - 100,000*0.05*2 =

*January 1, 2017*

**yes**

h/L = 2/5, L = 2.5h. h/W = 4/5, W = 1.25h. 2(h*L) + 2(h*W) = 108 m^2. 2(h*2.5h) + 2(h*1.25h) = 108, 5h^2 + 2.5h^2 = 108, h = 3.79 m. A = L*W = 2.5h*1.25h = 2.5*3.79 * 1.25*3.79 = 45 m^2.

*December 31, 2016*

**math**

P = Po + Po*r*t. P = 9000 + 9000*(0.105/365)*270.

*December 30, 2016*

**physics**

d = 0.5g*t^2. g = 9.8 m/s^2, t = 5s. V = Vo + g*t. Vo = 0, g = 9.8, t = 5s.

*December 30, 2016*

**Algebra**

not anonymous.

*December 29, 2016*

**Math**

8+2+7 = 17.

*December 28, 2016*

**MATH**

Log10^a = 4. 10^a = 4, a = 4.

*December 26, 2016*

**Math**

240seats/5rows = 48 seats/row. 240seats/6rows = 40 seats/row. Repeat for 8, 10, 12, 15, 16, 20, 24, 30, and 40 rows.

*December 24, 2016*

**algebra**

(5z-2)(5z+2) = 25z^2 +10z - 10z - 4 = 25z^2 - 4. or (5z)^2 - 2^2 = 25z^2 - 4.

*December 23, 2016*

**mystery**

See previous problem.

*December 23, 2016*

**mystery**

See previous problem.

*December 23, 2016*

**mystery**

0.45N = 17.1, N = 38.

*December 23, 2016*

**Maths**

See previous post: Thu, 12-22-16, 11:14 PM.

*December 23, 2016*

**Easy Maths QuestioPn**

1. Y = 5.80n. 2. P = 5.80n - 0.8n - 1250, P = 5n - 1250. 3. P = 5n - 1250 = 0, n = 250.

*December 22, 2016*

**electrical energy and power**

Pi = E*I = 240 * 7.5 = 1800 W. 2hp * 746W/hp = 1492 W. Eff. = Po/Pi = 1492/1800 = 0.829 = 82.9%.

*December 22, 2016*

**algebra**

(2m-4)(m^2+2m+4) = 2m^3 + 4m^2 + 8m-4m^2-8m-16 = 2m^3-16 = 2(m^3-8).

*December 22, 2016*

**Science: Physics**

Cost = 0.0479/kW * 228.125kWh =

*December 22, 2016*

**Science: Physics**

1. P = E*I= 2500. 230I = 2500, I = 10.9A. 2. R = E/I. 3. T = 365 * 15/60 = 91.25 h/yr. 4. Energy = kW * h = 2.5 * 91.25 = 228.125 kWh.

*December 22, 2016*

**physics**

R = 1.02 + 0.0039*(60-20)= 1.176 Ohms.

*December 21, 2016*

**math**

Please correct the errors in your problem.

*December 21, 2016*

**maths**

3.25x + 3.85(80-x) = 272. 3.25x - 3.85x + 308 = 272, X = ?.

*December 21, 2016*