# Posts by Henry

Total # Posts: 13,351

**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*

**Algebra 1**

Multiply Eq1 by 3, and convert Eq2 to standard form: Eq1: 6x + 3y = 9. Eq2: 6x + 3y = 9. The 2 Eqs are identical. Therefore, we have an infinite number of solutions.

*December 19, 2016*

**math**

5F + 5S = 575. F = S+15. 5(S+15) + 5S = 575.

*December 18, 2016*

**Physics**

Are you sure the child is only 5 m ahead? Vo = 50km/h = 50,000m/3600s = 13.89 m/s. a. V = Vo + a*t = 0. 13.89 + a*5 = 0, a = -2.80 m/s^2. V^2 = Vo^2 + 2a*d. V = 0, Vo = 13.89 m/s, a = -2.80m/s^2, d = ?. b.

*December 17, 2016*

**Math**

Or 5/4 = 1.25 = 125%. 125% - 100% = 25%.

*December 16, 2016*

**physics**

See previous post: Thu, 12-15-16, 9:33 PM.

*December 15, 2016*

**PHYSICS**

What is the question?. Vo = 30m/s[60o]. Xo = 30*Cos60 = 15 m/s. Yo = 30*sin60 = 25.0 m/s. Range = Vo^2*sin(2A)/g. A = 60o. Y^2 = Yo^2 + 2g*h. Y = 0, Yo = 25 m/s, g = -9.8 m/s^2, h = ?.

*December 15, 2016*

**p[hysics**

See previous post: Thu, 12-15-16, 9:33 PM.

*December 15, 2016*

**PHYSICS HELP!!!!!**

Vo = 25m/s[20o]. Xo = 25*Cos20 = 23.5 m/s. Yo = 25*sin20 = 8.55 m/s. Y = Yo + g*Tr = 0. 8.55 - 9.8Tr = 0, Tr = 0.873 s. = Rise time. Y^2 = Yo^2 + 2g*h = 0. (8.55)^2 - 19.6h = 0, h = 3.73 m. Above the cliff. 0.5g*Tf^2 = 3.73+8.4 4.9Tf^2 = 12.13, Tf = 1.57 = Fall time. Dx = Xo(...

*December 15, 2016*

**PHYSICS HELP**

Tan A = Y/X = (-50)/400 = -0.125, A = -7.125o = 7.125o S. of E.

*December 15, 2016*

**PHYSICS HELP**

X = 400 km/h. Y = 50 km/h. V = sqrt(X^2+Y^2).

*December 15, 2016*

**physics hw**

Vo = 87km/h = 87,000m/3600s = 24.2 m/s. = Initial velocity. a. d1 = 24.2 * 2 = V^2 = Vo^2 + 2a*d2. V = 0, Vo = 24.2 m/s, a = -4.0 m/s^2, d2 = ?. d1+d2 = Stopping distance. b. V^2 = Vo^2 + 2a*d2. V = 0, Vo = 24.2 m/s^2, a = -8.0 m/s^2, d2 = ?. d1+d2 = stopping distance.

*December 15, 2016*

**physics**

V1 = a*t = 2.5 * 5 = 7.5 m/s. a. V2 = V1 + a*t = 7.5 -(3 * 2) = 1.5 m/s. After the braking period. b. d1 = 0.5a*t^2 = 0.5*2.5*5^2 = 31.25 m. d2 = V1*t + 0.5a*t^2. d2 = 7.5*2 - 0.5*3*2^2 = 9 m. d = d1+d2 = 31.25 + 9 = 40.25 m.

*December 15, 2016*

**physics**

V^2 = Vo^2 + 2g*h = 0 + 19.6*29 = 568.4, V = 23.8 m/s. Work = KE2-KE1 = KE2-0 = KE2. Work = KE2 = 0.5M*V^2 = 0.5*41,000*(23.8)^2 = 11.7*10^6 J. Work = F*d = F*29 = 11.7*10^6, F = 4.03*10^5 N. d = 1m/4.1*10^5N. * 4.03*10^5N. = = 0.983 m.

*December 15, 2016*

**Physics**

M*g = Wt. of box = Normal force(Fn). Fp = Mg*sin o = 0. = Force parallel to the surface. Fk = u*Fn = u*M*g. V^2 = Vo^2 + 2a*d = (3.3)^2. (4.56)^2 + 2a*0.7 = 10.9, a = -7.07 m/s^2. Fp-Fk = M*a. 0-u*Mg = M*(-7.07), 0-u*M*9.8 = -7.07M, Divide both sides by -9.8M: u = 0.722.

*December 15, 2016*

**Physics**

Vo = 17.7 m/s[39.8o]. Yo = 17.7*sin(39.8) = 11.33 m/s. = Vert. component of Vo. Y = Yo + g*Tr = 0. 11.33 - 9.8Tr = 0, Tr = 1.16 s. = Rise time. T = Tr+Tf. Tf = Tr. T = Tr+Tr = 1.16 + 1.16 = 2.32 s.

*December 15, 2016*

**Physics**

A. F = M*g*30 = 71*9.8*30 = 20,874 N. = 2.09*10^4 N. B. Vo = 95km/h = 95,000m/3600s = 26.4 m/s. F = M*a = -20,874. a = -20,873/71 = -294 m/s^2. V^2 = Vo^2 + 2a*d. V = 0, Vo = 26.4 m/s, a = -294 m/s^2, d = ?.

*December 15, 2016*

**Business Math**

P = Po - Po*r*t. P = 9500-9500*(0.10/365)*95 = $9252.74. = Proceeds.

*December 15, 2016*

**Math**

db = 10*Log(Po/75) = 12. Log(Po/75) = 1.2, Po/75 = 10^1.2, Po = 1189 W.

*December 14, 2016*

**Physics**

a. Vo = 20m/s[45o]. Xo = 20*Cos45 = 14.14 m/s. Yo = 20*sin45 = 14.14 m/s. Y = Yo + g*t = 0. 14.14 - 9.8t = 0, t = 1.44 s. b. Y^2 = Yo^2 + 2g*h = 0. (14.14)^2 - 19.6h = 0, h = ?. c. Range = Vo^2*sin(2A)/g. A = 45o. d. T = Tr+Tf. Tf = Tr, T = Tr+Tr = 1.44 + 1.44 = 2.88 s. d.

*December 14, 2016*

**Math**

Invested: Po @ 2%. (2Po+2300) @ 9%. t = 1 yr.? I = Po*r*t + (2Po+2300)*r*t = 647. Po*0.02*1 + (2Po+2300)*0.09*1 = 647, 0.02Po + 0.18Po + 207 = 647, 0.20Po = 440, Po = $2200. 2Po+2300 = 2*2200 + 2300 = $6700.

*December 13, 2016*

**Mathematics**

1. (8,11). y/x = 11/8, Y = 1.375x. 2. correct. 3. y/x = 232/4 = 58/1. 4. (2,5), (8,3). m = (3-5)/(8-2) = -2/6 = -1/3.

*December 13, 2016*

**math**

Correction: 360cm^3/2^3 = 45 Cubes.

*December 13, 2016*

**physics**

Work = KE2-KE1 = KE2-0 = KE2. KE2 = 0.5M*V^2 = 10,000 J. 500*V^2 = 10,000, V = ?.

*December 12, 2016*

**Physics**

a. M*g = 1.35 * 9.8 = 13.2 N. = Wt. of book. = Normal force(Fn). Fs = us*Fn = 0.45 * 13.2 = 5.95 N. F-Fs = M*a. F = Fs+M*a = 5.95+M*0 = 5.95 N. b. Fk = uk*Fn = 0.30 * 13.2 = 3.96 N. F-Fk = M*a. a = (F-Fk)/M. c. Fap-Fk = M*a. Fap = Fk+M*a = 3.96 + M*0 = 3.96 N. = Force applied...

*December 12, 2016*

**Physics**

e. Fnet = M*a. a = Fnet/M.

*December 12, 2016*

**Physics**

a. M*g = 475 * 9.8 = 4655 N. = Wt. of sleigh. = Normal force(Fn). b. Fs = u*Fn = 0.20 * 4655 = c. Fk = uk*Fn = 0.15 * 4655 = d. Fnet = Fh-Fk = 150,000-4655 =

*December 12, 2016*

**Science**

F = M*a. = 20. a = 20/M = 20/60 = 0.333 m/s^2.

*December 11, 2016*

**physics**

See previous post: Sun, 12-11-16, 7:32 PM.

*December 11, 2016*

**Physics**

M*g = 180 * 9.8 = 1764 N. = Wt. of trunk. Fn = 1764 - 400*sin15 = 1661 N. = Normal force. Fap*Cos A-Fk = M*a. Fk = Fap*Cos A-M*a = 400*Cos15-M*0 = 386.4 N. = Force of kinetic friction. Fk = u*Fn = 386.4. u = 386.4/Fn = 386.4/1661 = 0.233 = Coefficient of kinetic friction.

*December 11, 2016*

**Physics**

3. V = Vo + a*t = 0. 25 + a*8 = 0, a = -3.1025 m/s^2 Thrust = M*a = 958/9.8 * (-3.125) = -305.5 N. 5. M*g = 3.0 * 9.8 = 29.4 N. = Wt. of block = Normal(Fn). Fs = u*Fn = 0.4 * 29.4 = 11.8 N. 7. M*g = 50 * 9.8 = 490 N. = Wt. of box = Normal(Fn). Fk = u*Fn = 0.35*490 = 171.5 N. F...

*December 11, 2016*

**Physics**

Y^2 = Yo^2 + 2g*h = 0. Yo^2 - 64*20 = 0, Yo = 35.8 Ft/s. Vo*sin30 = 35.8, Vo = 71.6 Ft/s.

*December 11, 2016*

**algebra**

See previous post: Sun, 9-11-16, 2:24 PM.

*December 11, 2016*

**algebra**

Donuts: $X ea. Coffee: $Y ea. Eq1: 3x + 4y = 4.91 Eq2: 5x + 6y = 7.59 Multiply Eq1 by 5 and Eq2 by (-3): +15x + 20y = +24.55 -15x - 18y = -22.77 Sum: 2y = 1.78, Y = 0.89 In Eq1 replace Y with 0.89: 3x + 4*0.89 = 4.91. X = ?

*December 11, 2016*

**algebra 1**

Right!

*December 11, 2016*

**algebra 1**

(-3,-7), (-5,-7). m = (-7-(-7))/(-5-(-3)) = 0/-2 = 0. Y = mx + b = -7. 0*x + b = -7, b = -7, Eq: Y = -7 = A horizontal line.

*December 11, 2016*

**algebra 1**

X 2-pointers. (16-x) 3-pointers. 2x + 3(16-x) = 38, 2x + 48 - 3x = 38, X = 10. 16-x = 16-10 = 6.

*December 11, 2016*

**algebra**

X 2-pointers. (16-x) 3-pointers. 2x + 3(16-x) = 38, 2x + 48 - 3x = 38, X = 10. 16-x = 16-10 = 6.

*December 11, 2016*

**math**

post it.

*December 11, 2016*

**Algebra**

x^2 - 6x + 9 > 0. (x-3)^2 > 0, Take sqrt of both sides: x-3 > 0, X > 3.

*December 10, 2016*

**Algebra**

h(t) = 240 - 16tT^2 = 0. 16t^2 = 240, t = 3.87 s. 6

*December 10, 2016*

**Math**

a. Net Cash = 780,000 - 270,000 - 60,000 - 0.05(780,000-200,000) = $421,000.

*December 10, 2016*

**Algebra**

18a. F(x) = x - 5. 18b. F(x) = x - 0.25x = x(1-0.25) = 0.75x.

*December 10, 2016*