Monday

January 16, 2017
Total # Posts: 13,037

**physic**

Tr = Rise time, Tf = Fall time. a. Tr + Tf = 2 s, Tf = Tr, Tr+Tr = 2, 2Tr = 2, Tr = 1 s. V = Vo + g*Tr = 0, Vo = -g*Tr = 9.8*1 = 9.8 m/s. b. Yo = 9.8 m/s(Part a), Vo*sin40 = 9.8, Vo = 9.8/sin40 = 15.25 m/s.

*February 3, 2016*

**physics**

a. V = 205mi/h * 1600m/mi * 1h/3600s = 91.1 m/s. V = Vo + a*t. V = 91.1 m/s, Vo = 0, t = 2.70 s. a = ?. b. d = 0.5a*t^2. a = Value cal. in part "a", t = 2.70 s, d = ?.

*January 31, 2016*

**physics**

a. V^2 = Vo^2 + 2g*h V = 0, Vo = 19.0 m/s, g = -9.8 m/s^2, h = ? b. V = Vo + g*t. V = 0, Vo = 19.0 m/s,g = -9.8 m/s^2, t = ?.

*January 31, 2016*

**science**

100%-30% = 70% Below the surface. Db/Dw = 0.7, Db = 0.7Dw = 0.7*0.998 = 0.699 g/cm^3.

*January 31, 2016*

**SCIENCE**

Wo = F*d=M*g * d = 150*9.8 * 2.5 = 3675 J. = Work output or work done. Input = 3675/0.6, but it did not ask for the input.

*January 31, 2016*

**science**

M*V = 1.4, 0.7*V = 1.4, V = ?.

*January 30, 2016*

**math**

100%-8% = 92%. Cost = 0.92 * 968

*January 30, 2016*

**Physics**

See previous post: Tue, 1-26-16, 1:52 PM.

*January 30, 2016*

**Math**

See previous post.

*January 29, 2016*

**Math**

See previous post.

*January 29, 2016*

**Math**

-15x+3 >= -3(4x-7). -15x+3 >= -12x+21. -15x + 12x >= 21-3. -3x >= 18. X <= -6. When multiplying or dividing an inequality by a negative number, the inequality sign should be reversed.

*January 29, 2016*

**science(physics)**

a. Vo = 36000m/3600s. = 10 m/s. a = -(Vo^2)/2d = -(10^2)/80 = -1.25 m/s^2. b. F = M*a = 100 * (-1.25) = -125 N. The negative sign means the force opposes the motion.

*January 28, 2016*

**Physics**

Xo = 21 m/s. Yo = 45 m/s. 1. Y = Yo + g*Tr = 0 at max.ht. Tr = -Yo/g = -45/-9.8 = 4.59 s. = Rise time. Tf = Tr = 4.59 s. = Fall time. Tr+Tf = 4.59 + 4.59 = 9.18 s. = Time in air. 2. R = Xo*(Tr+Tf) = 21m/s * 9.18s = 193 m. 3. A = 45o for max range. Vo = Sqrt(21^1+45^2) = 49.7 m...

*January 28, 2016*

**Physics - Am I correct?**

See previous post: Tue, 1-26-16, 1:52 PM.

*January 28, 2016*

**physic**

KE = 0.5*M*V.

*January 28, 2016*

**Physics**

Tan A = Y/X = 2.77/17.6 = 0.15737 A = 8.94o = Direction.

*January 28, 2016*

**Physics**

Vo = 18.7m/s[20o]. Xo = 18.7*Cos20 = 17.6 m/s. Yo = 18.7*sin20 = 6.40 m/s Y = Yo + g*t = 6.40 - 9.8*0.37 = 2.77 m/s. Tan A = Y/Xo = 2.77/17.6 = 8.94o = Direction.

*January 28, 2016*

**math**

(3x+2)^(1/3) = -2. Cube both sides: 3x+2 = -8. 3x = -10. X = -10/3.

*January 28, 2016*

**Physics**

1. V = Vo + g*t, g = -9.8 m/s^2. 2. a = g = -9.8 m/s^2. 3. V = Vo + g*Tr, V = 0, Vo = 70 m/s, g = -9.8 m/s^2, Tr = Rise time, Solve for Tr. 4. Tf = Fall time, T = Tr+Tf, Tf = Tr, T = Tr+Tr = 2Tr = Time required to reach gnd. 5. V^2 = Vo^2 + 2g*h = 0, h = -(Vo^2)/2g, g = -9.8 m...

*January 28, 2016*

**science**

V = Vo + a*t = 0.8 m/s. Vo = 0, t = 2 s. a = ?.

*January 27, 2016*

**Algebra**

Angle #1 = X Deg. Angle #2 = X Deg. Angle #3 = (X+9) Deg. x + x + x+9 = 180 Deg. 3x = 171. X = 57o x+9 = 57+9 = 66o = Largest angle.

*January 27, 2016*

**physics**

Wb = M*g = 15 * 9.8 = 147 N. Fn = 147 - 55*sin32 = 117.9 N. = Normal force. Fk = u*Fn = 0.25 * 117.9 = 29.5 N. = Force of kinetic friction. Work = (55*Cos32-29.5) * 15 = 257 Joules.

*January 27, 2016*

**Math**

k = 12Lbs/9in = 1.33 Lbs/in.

*January 27, 2016*

**Physics**

F = M*a = -7540 N. a = -7540/M = -7540/2700 = -2.79 m/s^2. V = Vo + a*t, V = 29.8 - 2.79*2.77 = 22.1 m/s.

*January 27, 2016*

**Physics**

V^2 = Vo^2 + 2g*h. V = 0, g = -9.8 m/s^2, h = 500 m. Vo = ?.

*January 27, 2016*

**math**

Fist book cost $X. 2nd book cost (3x+4) Dollars. x + 3x+4 = 72. X = ?

*January 27, 2016*

**physics**

If the capacitors are connected in series, C1*V1 = 150 uC, V1 = 150/C1 = 150/3 = 50 Volts. 120-50 = 70 Volts across other two capacitors.

*January 26, 2016*

**Physics**

3. M*V1 + M*V2 = M*V3 + M*V4. M*2.1 - M*3 = -M*3 + M*V4. V4 = ? 4. M1*V1 + M2*V2 = M1*V + M2*V. 1800*22i + 3200*14 = 1800V + 3200V. Divide both sides by 100 and solve for v.

*January 26, 2016*

**Physics**

1. M1 = M2 = M. Unless otherwise stated, all angles are measured CCW from +x-axis. M*V1 + M*V2 = M*V3 + M*V4. M*0 + M*V2 = M*0.92m/s[161o] + M*1.25m/s[46o]. M*V2 = 0.92M[161o] + 1.25M[46o]. Divide both sides by M and solve for V2 V2 = -0.87+0.30i + 0.87+0.90i = 1.20i = 1.20m/s...

*January 26, 2016*

**physics**

a. L = V/F = 5.1*10^-3. V/(2.8*10^5) = 5.1*10^-3. V = m/s. b. d = V*t; t = d/V = 3000/V.

*January 25, 2016*

**physics**

t = 21/5.6

*January 25, 2016*

**physics**

a. h = 0.5*g*t^2 = 0.4 m. g = 9.8 m/s^2. t = ?

*January 25, 2016*

**Physics**

d. d = Xo*T = 25m/s * 3s. = 75 m. e. Tr = 3s/2 = 1.50 s. = Rise time. e. Y = Yo + g*Tr = 0. Yo - 9.8*1.5 = 0. Yo = 14.7 m/s = Ver. component of initial velocity. f. Tan A = Yo/Xo = 14.7/25 = 0.58800. A = 30.5o.

*January 25, 2016*

**Physics**

h = 0.5g*t^2 = 1.52

*January 25, 2016*

**Physics**

V^2 = Vo^2 + 2g*h = 0 +19.6*1.25 = 24.5 V = 4.95 m/s. V(avg) = (Vo+V)/2 = (0+4.95)/2 = 2.47 m/s.

*January 25, 2016*

**physics**

Wc = M*g = 100kg * 9.8N/kg = 980 N. = Normal(Fn). Fap-Fk = M*a. 450-u*980 = M*0 = 0. -980u = -450. u = 0.459

*January 25, 2016*

**physics**

See previous post: Sun, 1-24-16, 10:49PM.

*January 24, 2016*

**physics**

d = r*t = 4.8*10^6m. 300*t = 4.8*10^6 t = 16,000 s. = 4.44 h.

*January 24, 2016*

**Physics**

X = 580 km/h = Velocity of airplane. Y = 92 km/h = Velocity of wind. Tan A = Y/X = 92/580 = 0.15862 A = 9.0o N. of E. Speed = Sqrt(X^2+Y^2) = km/h. Since the wind is northward, the direction is N. of E. NOT S. of E.

*January 24, 2016*

**Electronics Engineering Technology**

dbm = 10*Log(Po/Pi) = 10. 10*Log(Po/1) = 10. Log(Po/1) = 1.0. Po/1 = 10^1 = 10. Po = 10 mW = Power output of driver to transmitter. Po = Vo^2/R = 10 mW = 0.01 W. Vo^2/600 = 0.01 Vo^2 = 6. Vo = 2.45 Volts across 600 Ohms.

*January 24, 2016*

**math**

(7,5), (8,7), (x,11). Slope = (7-5)/(8-7) = 2. Slope = (11-7)/(x-8) = 2. 2x-16 = 4. X = 10.

*January 24, 2016*

**physics**

d = 0.5a*t^2.

*January 24, 2016*

**PHYSICS**

Vo = 50mi/h = 22.22 m/s. Wt. = 3000Lbs = 1362 kg. d = 200Ft = 60.61 m. a = -Vo^2/2d = -(22.22^2)/121.2 = -4.07 m/s. Fb = M*a = 1362 * (-4.07) = -5543 N. = Braking force. V = Vo + a*t = 0. t = -Vo/a = -22.22/-4.07 = 5.45 s. = Time required to stop.

*January 23, 2016*

**PHYSICS**

Mass = 1420Lbs * 0.454kg/Lb. = kg Wt. = M*g = 412kg * 9.8N/kg = Newtons.

*January 23, 2016*

**Science**

d = 0.5a*t^2.

*January 23, 2016*

**Algebra 2**

3a. V^2 = Vo^2 + 2g*h = 0. h = -Vo^2/2g + 70 = 422 Ft = Ht. above gnd. V = Vo + g*Tr = 0. 150 - 32*Tr = 0. 32Tr = 150. Tr = 4.7 s. = Rise time or time to reach max. ht. b. h = 0.5g*Tf^2 = 422. 16Tf^2 = 422. Tf^2 = 26.375. Tf = 5.14 s. = Fall time. Tr+Tf = 4.7 + 5.14 = 9.84 s...

*January 22, 2016*

**science**

(T-20)oC * 25*10^-6m/oC = 10^-3m. 25*10^-6T - 5*10^-4 = 10^-3 25*10^-6T = 1.5*10^-3 T = 0.06*10^3 = 60 oC.

*January 22, 2016*

**Science**

d = V*T = 8.66*10^7km = 8.66*10^10 m. 3*10^8 * T = 8.66*10^10.

*January 21, 2016*

**ALgebra**

X = $10-coins. 54-x = $20-coins. 10x + 20(54-x) = 780. 10x + 1080 - 20x = 780. -10x = -300. X = 30. 54-x = 54-30 = 24

*January 21, 2016*

**Math**

Do you mean V = (128/9)pi? V = pi*r^2*h = (128/9)pi. 3.14*r^2*8 = 44.7 r^2 = 1.78 r = 1.33 In. D = 2r = 2.7 In.

*January 21, 2016*

**Math**

4m * 100cm/m = 400 cm. 4m + 20cm = 400cm + 20cm = 420 cm.

*January 21, 2016*

**physics**

X = 8.30 m. Y = 7.00 m. Tan A = Y/X = 7.00/8.30 = 0.84337

*January 21, 2016*

**math**

As = 2pir^2 + 2pi*r*h = 6.28*2^2 + 6.28*2*9 = 138.2 In^2. 138.2In^2 * 1Ft^2/144In^2 = 0.959 Ft^2. 0.959Ft^2/box * 1500boxes = 1439.2 Ft^2. of cardboard.

*January 21, 2016*

**Math**

1/(1/4) * 1/2 = 1*4/1 * 1/2 = 2 Cups of apple juice.

*January 20, 2016*

**Math**

Width = W cm. Length = W+8 cm. 2W + 2(W+8) = 84 cm W = ?.

*January 20, 2016*

**Business Math**

Correction: Change 0.04 to 0.044.

*January 20, 2016*

**Business Math**

Check: I counted 213 days. I = Po*r*t = 760*(0.04/365)*213 =

*January 20, 2016*

**Math**

A. (1/2)/(1/4) = 1/2 * 4/1 = 2 Batches of brownies. A. (4 4/5)/(2/5) = (24/5)/(2/5) = 24/5 * 5/2=120/10=12 Two-fifth pieces of rope. B. So their are 12 two-fifths in four and four-fifth. (32 1/4)/(1/8) = 258. A. B. 32 1/4 * 8 or 129/4 * 8. C. There are 258 one-eights in 32 1/4...

*January 20, 2016*

**math**

Ordinary Interest Ar = Ab - Ab*r*t. Ar = 500 - 500*(0.09/360)*82 = Amount received or Discounted value. Ar = 1000 - 1000*(0.15/360)*55 = Amount received or Discounted value.

*January 20, 2016*

**math**

Cost = (13.98+3.96)/6 =

*January 19, 2016*

**Math**

Ap=L*W = 100cm * 20cm=2000 cm^2 = Area of the paper. As = 2(W*h) + 2(L*h) + 2(L*W) = Surface area box. As=2(15*15) + 2(15*15) + 2(15*15) = 6(15^2) = 1350 cm^2. Ap-As = 2000 - 1350 = 650 cm^2 Left.

*January 19, 2016*

**math**

width = W Feet. Length = 2W+4 Feet. A = (2W+4)*W. (2W+4)*W = 100.

*January 19, 2016*

**Math**

X dimes. 81-x nickels. 0.1x + 0.05(81-x) = 5.75 Multiply both sides by 100: 10x + 5(81-x) = 575. x = ?

*January 19, 2016*

**algebra**

-9m^-2*n^5*2m^-3*n^-6 = -18m^-5*n^-1 = -18/m^5*n. Answer: B.

*January 19, 2016*

**algebra**

Day 1. x miles. 2. 3x+52 miles. 3. x-83 miles. D = x + 3x+52 + x-83 = 5x - 31.

*January 19, 2016*

**how to set this up**

See previous post: Tue, 1-19-2016, 1:56 PM .

*January 19, 2016*

**8th grade Algebra**

49z^4-25y^4=(7z^2+5y^2)(7z^2-5y^2).

*January 19, 2016*

**i dont know how to solve this**

History: 0.93 = 93%.

*January 19, 2016*

**i dont know how to solve this**

English: (13/14)*100% = 92.9% Science: 93%. Math: (25/27)*100% = History: 9.93 = 93%.

*January 19, 2016*

**how to set up this problem**

Bal.=Ao - ((1/3)Ao+17.11+26.74) = Ao = $75 = Initial amount.

*January 19, 2016*

**math**

I = Po*r*t = $20. 325*(r/12)*2 = 20. 325*r/6 = 20. 325r = 120. r = 0.369 = 36.9% APR.

*January 19, 2016*

**Math**

P = Po(1+r)^n. r = (0.05/12)*1/2 = 0.0020833 = Semi-monthly % rate. n = 2Comp/mo. * 300mo = 600 Compounding periods. Solve for P. I = P-Po.

*January 19, 2016*

**Math**

P = Po + Po*r*t = 10,000. Po + Po*(0.04/52)*13 = 10,000. Po + 0.01Po = 10,000. 1.01Po = 10,000. Po = $9900.99

*January 19, 2016*

**Math**

P = Po(1+r)^n = 2M. Po(1.04)^35 = 2. 3.94609Po = 2. Po = 0.50683M. = $506,830.

*January 18, 2016*

**math**

P = Po(1+r)^n. r = (7%/12)/100% = 0.005833 = Monthly % rate expressed as a decimal. n = 12Comp/yr. * 1.5yrs. = 18 Compounding periods. P = 7000(1.005833)^18 = $7737.90. APY = ((P-Po)/Po)*100 =

*January 15, 2016*

**Math**

2. Given: P(0,5), m = 1/2. Y = mx + b = 5. (1/2)*0 + b = 5, b = 5. Eq: Y = (1/2)x + 5. 3. Given: (1,2), (2,3). m = (3-2)/(2-1) = 1/1 = 1. Y = mx + b = 2. 1*1 + b = 2, b = 1. Eq: Y = x + 1. 8. Same procedure as #3. 9. Given: (2,3), (x,y), m = -2. m = (y-3)/(x-2) = -2. Cross ...

*January 15, 2016*

**Math**

Y = (2/3)x + 2 x = 0 at the point where the graph crosses the y-axis. So in the Eq above, replace x with 0 and solve for y: Y = (2/3)*0 * 2 = 0 + 2 = 2. (x,y) = (0,2).

*January 15, 2016*

**Math**

P = 1,092 - (1/3+2/7)*1,092 = 1,092 - (7/21+6/21)*1092 = 1092 - (13/21)*1092 = 1092 - 676 = 416.

*January 15, 2016*

**physics**

Fap-Fk = M*a 550.27-Fk = M*0 = 0. Fk = 550.27 N.

*January 15, 2016*

**ECE**

Vb-a = 3 + 2 = 5 Volts. Va-b = -2 + -3 = -5 Volts. If the problem asked for Vb-a, I would say, +5 volts. If it asked for Va-b, I would say negative 5 volts. But it didn't ask for neither of the above; therefore, my answer would be "Five volts".

*January 15, 2016*

**Physics**

Vo = 1.67m/s[30o]. Yo = 1.67*sin30 = 0.835 m/s. Y = Yo + g*t = 0. 0.835 - 9.8*t = 0. 9.8t = 0.835. t = 0.0852 s. = 8.52*10^-2 s.

*January 15, 2016*

**Physics**

Fm = M*g=40kg * 9.8N/kg = 392 N. = Force of the mass. T1*Cos25 = -T2. T2 = -T1*Cos25 = -0.91T1. T1*sin25 = 392. T1 = 928 N. T2 = -0.91*T1 = -0.91 * 928 = -841 N.

*January 14, 2016*

**Maths**

a. 17/20 b. (17/20) * 100% =

*January 14, 2016*

**Maths**

4.39

*January 14, 2016*

**Maths**

5.078, 5.08, 5.287, 5.78, 5.8

*January 14, 2016*

**Math**

1. Friend's lunch = F. Your lunch = F+3. f + f+3 = 19. 2. Jason's wt. = 36 Lbs. His sister's wt. = w Lbs. w + 36 = 3w+4. 3. X packages sold last year. 35 = 2x-1. 4. 10 + x = 70. 5. 60 + x > 200. 6. 6.25h >= 143.75. your

*January 12, 2016*

**math help**

20 - 5 - 0.75x = 0. 20-5-0.75x = 0. 0.75x = 15. X = 20 Tickets.

*January 12, 2016*

**Algebra**

1. (3,8), (9,5). m = (5-8)/(9-3) = 2. (-7/2,-3), (-5,5/2). m = (5/2-(-3))/(-5-(-7/2)) = (5/2+6/2)/(-10/2+7/2) = (11/2)/(-3/2) = 11/2 * (-2/3) = -22/6. 3. (8,3), (x,y), m = 5. m = (y-3)/(x-8) = 5. Cross multiply: y-3 = 5(x-8).

*January 12, 2016*

**Algebra**

5k - 2k + 4k + 0.005k = 7.005k.

*January 11, 2016*

**math**

x^3 = 3.85*10^-17. Take the cube root of both sides by raising it to the 1/3 power: (X^3)^(1/3)=(3.85*10^-17)^(1/3). X = 3.38*10^-6.

*January 11, 2016*

**Trigonometry**

h/38 = 0.34/0.69

*January 11, 2016*

**Math**

42 < -6d. -7 > d. or d < -7.

*January 11, 2016*

**physics**

a = (V-Vo)/t. Initial Momentum = M*Vo. Final momentum = M*V. Change in momentum = M*V-M*Vo. F = M*a.

*January 11, 2016*

**Math**

See previous post.

*January 11, 2016*

**Math**

Multiply Eq1 by -2 and add: Eq1: -3x - 4y = -22. Eq2: +3x + 6y = 22. Sum: 2y = 0. Y = 0. In Eq2, replace y with 0 and solve for x: 3x + 6*0 = 22. X = 7 1/3. One solution.

*January 11, 2016*

**Math Check (thanks)**

1. 6/(4*5) = 6/20 = 3/10 = 30%. 3. 19/25 = 0.76 = 76%. 4. 0.09 * 100% = 9%. 5. 37.1%/100% = 0.371. 6. 0.8 = 80%; 7/8 = 87.5%. 19/25 = 0.76 = 76%. Order: 19/25, 0.8, 81%, 7/8. 7. (165/250) * 100% = 8. (4/15) * 100% = 9. (52/5) * 100% = 10. 365%/100% = 3.65 = 3 13/20. 11. 100...

*January 11, 2016*

**Math**

A semicircular shape is in a (fills it) rectangle. If the perimeter of the rectangle is 30 cm, fine the perimeter of the semicircular shape.

*January 11, 2016*

**Algerbra**

y + 4x = 3. y + 4*(-1) = 3. Y = 7. (-1,7). y + 4*5 = 3. Y = -17. (5,-17).

*January 10, 2016*

**Physics**

Vo = 100m/s[30o]. Yo = 100*sin30 = 50 m/s. Y^2 = Yo^2 + 2g*h. h = (Y^2-Yo^2)/2g + ho. y = 0. g = -9.8 m/s^2. ho = 100 m. h = ?

*January 10, 2016*

**math**

(-6,1), (-3,2). m = (2-1)/(-3-(-6))/ = 1/3. Y = mx + b. (1/3)(-6) + b = 1. -2 + b = 1. b = 3. Y = (1/3)x + 3.

*January 10, 2016*