Thursday

April 2, 2015

April 2, 2015

Total # Posts: 10,349

**Physics**

See current post: Sat, 10-11-14, 11:51AM
*October 10, 2014*

**physics**

a. D = Vo*t + 0.5g*t^2 D = 15*1 - 4.9*1^2 = 10.1 m. V = Vo + g*t = 15 - 9.8*1 = 5.2 m/s Tr = -Vo/g = -15/-9.8 = 1.53 s. = Rise time. h max = -(Vo^2)/2g = -(15^2)/-19.6 = 11.48 m. Above launching point. Tf = 4 - 1.53 = 2.47 s. D = 4.9*Tf^2 = 4.9*2.47^2 = 29.9 m After 4 s. V^2...
*October 10, 2014*

**physics**

F1 = 100*Cos60 = 50 N. F2 = 100*sin60 = 87 N.
*October 10, 2014*

**Math**

C is correct.
*October 10, 2014*

**Physics**

Mass = 180Lb * 0.454kg/Lb = 81.72 kg. m*g = 81.72 * 9.8 = 801 N = Wt. of crate = Normal(Fn). Fs = u*Fn = 0.56 * 801 = 449 N. = Force of static friction. = Hor. component of applied force(Fx). Fk = u*Fn = 0.350 * 801 = 280 N. = Force of kinetic friction. a = (Fx-Fk)/m = (449-...
*October 9, 2014*

**physics**

L = 523 m. V = 4.6 km/s. = 4600 m/s. a. L = V*(1/F) = V/F = 523 m 4600/F = 523 523F = 4600 F = 8.8 c/s = 8.8 Hz. b. L = V/F = 7500/8.8 = 852.3 m.
*October 9, 2014*

**physics**

See previous post: Wed, 10-8-14, 7:55PM
*October 8, 2014*

**physics**

I = E/5R = 9.74 Amps E = 5R * 9.74 = 48.7R I = E/6R = 48.7R/6R = 8.12 Amps.
*October 8, 2014*

**physics**

D = 200yds[200o] + 300yds[130o] + 400yds [80o]. X = 200*Cos200 + 300*cos130o + 400*Cos80 = -311.3 Yds. Y = 200*sin200 + 300*sin130 + 400*sin80 = 555.3 Yds. Tan Ar = Y/X = 555.3/-311.3 = -1.78391 Ar = -60.73o = Reference angle. A = -60.73 + 180 = 119o CCW = 29o W. of N. = ...
*October 8, 2014*

**math**

X Bananas Ann ate X/3 Re = X - X/3 = 2X/3. Bob ate 1/3 * 2X/3 = 2X/9 Re = 2X/3 - 2X/9 = 4X/9. Carl ate 1/3 * 4X/9 = 4X/27 Re = 4X/9 - 4X/27 = 8X/27 Don ate 1/4 * 8X/27 = 8X/108 = 2X/27 Re = 8X/27 - 2X/27 = 6X/27 = 2X/9. 2X/9 = 12 2X = 108 X = 54 Bananas.
*October 8, 2014*

**Physics 203**

Let: m1 = 6 kg m2 = 1 kg KE1 = 0.5m1*V1^2 = 04 * (0.5m2*V2^2) 0.5*6*V1^2 = 0.4 * 0.5*1*V2^2 3V1^2 = 0.2V2^2 3V1^2/V2^2 = 0.2 V1^2/V2^2 = 0.2/3 V1/V2 = 0.258
*October 8, 2014*

**Engineering**

a. Vpg + Vw = 600km/h[-90o] = -600i Vpg + 125 = -600i Vpg = -125 - 600i Tan Ar = Y/X = -600/-125 = 4.80 Ar = 78.23o = Reference angle. A = 78.23 + 180 = 258.23o CCW = 11.8o W. of S. = Heading. b. Vpg = Y/sin A = -600/sin258.23 = 613 613 km/h. = Velocity of plane relative to gnd.
*October 8, 2014*

**Math**

Tan40 = h/L = h/24 h = 24*Tan40 = 20.14 cm V = L*W*h = 24 * 7 * 20.14 = 3383 cm^3.
*October 8, 2014*

**physics**

The distance is horizontal, but no hor. force is applied; therefore, no work is done. W = Fx*d = 0 * 50 = 0
*October 8, 2014*

**physics**

Work = Fx*d = 30*CosA * 50 = 1100 J. 1500CosA = 1100 CosA = 0.73333 A = 42.8o
*October 8, 2014*

**Math**

a. V = Vo + g*t = 320 - 32*5 = 160 Ft/s.
*October 7, 2014*

**Math**

a. V = Vo + g*t = 0 Vo - 32*2 = 0 Vo = 64 Ft/s. b. Tf1 = Tr = 2 s. = Fall time from hmax to top of cliff. Tf2 = 7-Tr-Tf1 = 7 - 2 - 2 = 3 s. = Fall time from top of cliff to gnd. h = Vo*Tf2 + 0.5g*Tf2^2 h = 64*3 + 16*3^2 = 336 Ft. = Ht. of cliff. c. What is time t? d. h max = ...
*October 7, 2014*

**Math**

When the ball returns to the roof, its velocity will be 80 Ft/s. V^2 = Vo^2 + 2g*h = 80^2 + 64*48 = 9472 V = 97.32 Ft/s.
*October 7, 2014*

**Physics**

X = -40 m/s. Y = 5m/s^2 * 6s. = 30 m/s. A. Tan Ar = Y/X = 30/-40 = -0.750 Ar = -36.9o = Reference angle. A = -36.9 + 180 = 143.1o CCW = 53.1o W. of N. V = X/Cos A = -40/Cos143.1 = 50 m/s @ 143.1o CCW or 53.1o W. of N.
*October 7, 2014*

**physics**

a = 22,000 - 800*12 =
*October 7, 2014*

**Math**

Eleanor and Max used two rectangular wooden boards to make a set for the school play. 1 board was 6 ft long, the other was 5 1/2 ft long. The 2 boards had equal widths. The total area of the set was 60 3/8 square ft. What was the width?
*October 7, 2014*

**Physics**

What are the units for #30?
*October 7, 2014*

**math**

Perimeter = 4 * 6m = 24.0 m. = Amt. of fencing needed.
*October 7, 2014*

**physics**

m*g = 1.75 * 9.8 = 17.15 N. = Wt. of block. Fn = 17.15 + 53.5*sin32 = 45.5 N. = Normal = Force perpendicular to the floor. Fk = u*Fn = 0.343 * 45.5 = 15.61 N. = Force of kinetic friction. a = (Fx-Fk)/m = (53.5*Cos32-15.61)/1.75 = 17 m/s^2.
*October 7, 2014*

**physics**

A. m1*V-m2*V2 = 10,000*5-1,500*14=29,000 m1*V+m2*V = 29,000 10,000*V + 1500*V = 29000 11,500V = 29000 V = 2.52 m/s. In the direction of the truck. B. KE1 = 0.5m1*V1^2 = 0.5*10,000*5^2 = 125,000 J. = 125 kJ. Before collision. KE1 = 0.5*m1*V^2 = 0.5*10,000*2.52^2 = 31,752 J. = ...
*October 6, 2014*

**physics**

d = 0.5m/s * 195s = 97.5 m. Head-start. d2 = d1 + 195 m. 0.5*a*t^2 = r*t + 195 0.5*3*t^2 = 0.5*t + 195 1.5t^2 - 0.5t - 195 = 0 Use Quadratic formula. t = 11.6 s.
*October 6, 2014*

**physical science**

Conclusion: m1*V1 = m2*V2. 2*V1 = 1*V2 V2 = 2V1
*October 6, 2014*

**Physics**

X = 25 m/s. Y = 200 m/s. Tan A = Y/X = 200/25 = 8.00 A = 82.9o Vp = Y/sin A = 200/sin82.9 = 202 m/s. = Velocity of the plane. d = 202m/s[82.9] * 3600s = 728,147 m. @ 82.9o
*October 6, 2014*

**Physics**

a. D=1.10km - 0.624i km + 1.09km[161.8o] X = 1.10 + 1.09*cos161.8 = 0.0645 km. = 64.5 m. Y = - 0.645 + 1.09*sin161.8 = -0.305 km. = -305 m. Tan A = Y/X = -305/64.5 = -4.72868 A = -78.06o CW = 78.06o S. of E. D = Y/Sin(-78.06) = -305/Sin(-78.06) = 312 m.[-78.06]. b. V = D/t = ...
*October 5, 2014*

**physics**

Xo = 3.76 m/s. 0.5g*t^2 = 6 m. 4.9t^2 = 6 t^2 = 1.22 Tf = 1.11 s.= Fall time. Dx = Xo*Tf = 3.76m/s * 1.11s. = 4.16 m.
*October 5, 2014*

**Algebra 1 Check**

2. 2*Sqrt(43x) = 14*Sqrt(43) Square both sides: 4*43x = 196*43 4x = 196 X = 49
*October 5, 2014*

**Physics Resistance**

R/4 Ohms/wire. Rb = 1/4 * R/4 = R/16 or 1/16R = Resistance of the bundle.
*October 5, 2014*

**physics**

EFF. = (Wo/Wi)*100% = (91/224)*100% = 40.6 %.
*October 4, 2014*

**physics**

Work = The change in kinetic energy. Work = KE2-KE1 = 0.5*m*V2^2-0.5*m*V1^2 = 0.5*550*3.2^2-0.5*550*1.5^2 = 2197 J.
*October 4, 2014*

**Physics**

Y^2 = Yo^2 + 2g*h = 0 Yo^2 - 19.6*1.1 = 0 Yo^2 = 21.56 Yo = 4.64 m/s. Vo = Yo/Sin A = 4.64/sin45 = 6.57 m/s @ 45o.
*October 4, 2014*

**Science**

a = F/m F = 420 N. m = 0.15 kg a in m/s^2
*October 4, 2014*

**Intro to Physical Science**

V = Vo = 6 m/s.
*October 4, 2014*

**Physics**

R1 = 61.5 Ohms. R2 = 146.6 Ohms. R3 = 16 Ohms. V = 13.6 Volts. a. Rt = R1*R2/(R1+R2) + R3 Rt = (61.5*146.6)/(61.5+146.6) + 16 = 59.32 Ohms. = Total resistance. I = V/Rt = 13.6/59.32 = 0.229 Amps. b. V2 = I*(R1*R2)/(R1+R2)=0.229 * 43.32 = 9.92 Volts. = Voltage across R2. P2 = ...
*October 3, 2014*

**Physics**

m*g = 36 * 9.8 = 352.8 N. KE+PE = 460 J. 185 + PE = 460 PE = 275 J. = mg*h mg*h = 275 352.8h = 275 h = 0.779 m.
*October 3, 2014*

**physics**

Fap = 340 N.[20o] Above the hor. Mass = 54 kg. u(k) = 0.4 m*g = 54 * 9.8 = 529.2 N. = Wt. of object. Fn = m*g+Fap*sin20=529.2 N. + 340*Sin20 = 645.5 N. = Normal = Force perpendicular to the surface. Fk = u*Fn = 0.4 * 645.5 = 258.2 N. a = (Fap*Cos20-Fk)/m = (319.5-258.2)/54= 1....
*October 3, 2014*

**physics help**

Based on the information given, 245 N. is too low. Please check all of the given INFO for accuracy.
*October 3, 2014*

**physics**

a. d = 0.5g*t^2 = 0.095 m. 4.9t^2 = 0.095 t^2 = 0.0194 Tf = 0.139 s. = Fall time or time in air. b. Dx = Xo*Tf = 20.6 Xo * 0.139 = 20.6 Xo = 148 m/s.
*October 3, 2014*

**AC DC Circuit fundamentals**

V = 12 Volts. R1 = 10k Ohms. R2 = 5k Ohms. I = V/(R1+R2) = 12/(10k+5k) = 0.8 mA. V1 = I*R1 = 0.8mA * 10k = 8 Volts. V2 = I*R2 = 0.8mA * 5k = 4 Volts.
*October 2, 2014*

**physics**

a = F/m = 7950/0.040 = 198,750 m/s^2. V^2 = Vo^2 + 2a*d Vo^2 = V^2 - 2a*d = 0 + 2*198750*0.011 = 4373 Vo = 66.1 m/s.
*October 2, 2014*

**Physics**

a. m*g = 0.6 * 9.8 = 5.88 N. = Wt. of the ball. Work = F*d = 5.88 * (6.1-1.2) = 28.8 J. b. PE = mg*h = 5.88 * 6.1 = 35.87 J. c. PE = mg*h = 5.88 * 1.2 = 7.06 J. d. (PEo-PEf) = 35.87 - 7.06 = 28.81 J. = The work done on the ball.
*October 2, 2014*

**Physics**

a. Box 1 V^2 = Vo^2+2g*h = 0 + 19.6*(4.8-1.2) = 70.56 V = 8.4 m/s. b. Box 2. V^2 = Vo^2+2g*h = 0 + 19.6*(4.8-1.2) = 70.56 V = 8.4 m/s. c. KE2/KE1 = 0.5m2*V^2/0.5m1*V^2 = 24*70.56/4.5*70.56 = 5.33 = m2/m1.
*October 2, 2014*

**physics**

h max = (V^2-Vo^2)/2g = (0-(20)^2/-19.6 = 20.41 m. V^2 = Vo^2 + 2g*h = 0 + 19.6*(20.41-5) = 302. V = 17.4 m/s
*October 1, 2014*

**Physics**

X = 1 km. Y = 1 km. Tan A = Y/X = 1 A = 45o D = X/Cos A = 1/Cos45 = 1.414 km[45o]
*October 1, 2014*

**Physics**

Fth = 1.250*10^7 N. = Force of thrust. Ra = 4.50*10^6 N. = Air resistance. m = 5.00*10^5 kg = Mass of the rocket. a = (Fth-Ra)/m
*October 1, 2014*

**physics**

Vo = 80km/h = 80000m/3600s = 22.22 m/s. V = 55km/h = 55000m/3600s = 15.28 m/s. Work = KE1-KE2 = o.5m*Vo^2-0.5m*V^2 = 935*22.22^2 - 935*15.28^2 = 461,636 - 218,302 = 243,334 J.
*October 1, 2014*

**Physics**

Xo = 39.0 m/s. h = 0.5g*t^2 = 16 m. 4.9t^2 = 16 t^2 = 3.27 Tf = 1.81 s. = Fall time. Dx = Xo*Tf = 39m/s * 1.81s = 70.5 m.
*October 1, 2014*

**physics**

m*g = 220kg * 9.8N/kg = 2156 n. = Wt. of the log. Fp = 2156*sin26.6 = 965.4 N. = Force parallel to the incline. Fn = 2156*Cos26.6 = 1928 N. = Normal. = Force perpendicular to the incline. Fk = u*Fn = 0.863 * 1928 = 1664 N. = Force of kinetic friction. Fex-Fp-Fk = m*a Fex-965.4...
*October 1, 2014*

**physics**

a1=(V-Vo)/t = (0.4-0.1)/5.5=0.055 m/s^2 a2 = (V-Vo)/t = (1.05-0)/15 = 0.07 m/s^2 F2=(a2/a1)*5N. = (0.07/0.055)*5N. = 6.36 N.
*September 30, 2014*

**physics**

What is a slug?
*September 30, 2014*

**physics**

a. Fn = (m1+m2)*g = (10+20)*9.8 = 294 N. b. Fn = m1*g = 10 * 9.8 = 98 N.
*September 30, 2014*

**Physics**

kg or kilograms.
*September 30, 2014*

**Physics**

m*g = 12kg * 9.8N/kg = 117.6 N. = Wt. of box. Fp = 117.6*Sin30 = 58.8 N. = Force parallel to the incline. Fn = 117.6*Cos30 = 101.8 N. = Normal = Force perpendicular to the incline. Fk = u*Fn = 0.29 * 101.8 = 29.53 N. = Force of kinetic friction. Fex-Fp-Fk = m*a Fex-58.8-29.53...
*September 30, 2014*

**physics**

A. h = 0.5g*t^2 = 0.7 m. 4.9t^2 = 0.7 t^2 = 0.1429 Tf = 0.378 s. = Fall time. B. Dx = Xo*Tf = 1 m Xo * 0.378 = 1 Xo = 1/0.378 = 2.65 m/s. = Initial hor. velocity.
*September 29, 2014*

**physics**

Tan5 = Y1/X = Y1/1.8 Y1 = 1.8*Tan5 = 0.157 km = Ht. of hill. Tan6.8 = (Y1+Y2)/X = (Y1+Y2)/1.8 Y1+Y2 = 1.8*Tan6.8 = 0.215 km Y2 = 0.215-Y1 = 0.215-0.157 = 0.058 km. = 58 m. = Ht. of tower.
*September 29, 2014*

**physics**

KE+PE = 520 J. 250 + PE = 520 PE = 520-250 = 270 J. mg*h = 270 h = 270/m*g = 270/(42*9.8) = 0.656 m.
*September 29, 2014*

**physics**

Case #1: Momentum = m1V1-m2V2 =8*25-3*0 = 200 Momentum = (m1+m2)V = 200 (8+3)*V = 200 V = 18.18 m/s Case #2: Momentum. = 3*25-8*0 = 75 (m1+m2)*V = 75 (8+3)*V = 75 V = 6.82 m/s
*September 29, 2014*

**physics**

m*g = 302kg * 9.8N/kg = 2960 N. = Wt. of motorcycle. Fp = 2960*sin24 = 1204 N. = Force parallel to the ramp. Fa = 235 N. = Force of air resistance. a = (Fap-Fp-Fa)/m = (2860-1204-235)/302= 4.71 m/s^2
*September 29, 2014*

**physics**

a = (V-Vo)/t V = 12 m/s Vo = 3.19 m/s. t = 5.4 s.
*September 29, 2014*

**Physics**

Rock #1: Vo1 = 7.70m/s[10o]. Downward. Yo1 = 7.70*sin10 = 1.34 m/s. h1 = Yo1*t + 0.5g*t^2 1.34*3.7 + 4.9*3.7^2 = 72.0 m Below top of the tower. Rock #2: Vo2 = 7.70m/s[50o], Up. Yo2 = 7.70*sin50 = 5.90 m/s h2 = Yo2*t + 0.5gt^2 h2 = 5.90*3.7 - 4.9*3.7^2 = -45.3 m. = 45.3 m. ...
*September 28, 2014*

**Physics**

V = 117km/h = 117000m/3600s. = 32.5 m/s. V^2 = Vo^2 + 2a*L = 32.5^2 0 + 4.8*L = 1056.25 L = 1056.25/4.8 = 220 m.
*September 28, 2014*

**Physics**

V = 117km/h = 117000m/3600s. = 32.5 m/s. V^2 = Vo^2 + 2a*L = 32.5^2 0 + 4.8*L = 1056.25 L = 1056.25/4.8 = 220 m. V = Vo + a*t = 32.5 m/s. 0 + 2.4*
*September 28, 2014*

**physical**

See previous post: Fri, 9-26-14, 12:49AM
*September 28, 2014*

**friction**

m*g = 10kg * 9.8N/kg = 98 N. = Wt. of the block. Fk = u*mg = 0.40 * 98 = 39.2 N. = Force of kinetic friction. a = Fk/Ms = 39.2/40 = 0.98 m/s^2.
*September 28, 2014*

**physics**

Fp = mg*sin31.7 = Force parallel to the Inclined plane = Scale reading. Fn = mg*Cos31.7 = Normal = Force perpendicular to the inclined plane.
*September 28, 2014*

**Physics**

a. d = 120 + (3/4)*120 = 120 + 90=210 m. r = d/t = 210m/30s. = 7 m/s. = Avg. speed. b. V = (120-90)/30 = 1 m/s. = Average velocity.
*September 27, 2014*

**physics**

a. m*g/6 = 100kg * (9.8/6)N/kg = 163.3 N. = Wt. on the moon.
*September 27, 2014*

**physics**

a = F/m = -5000/1500 = -3.33 m/s^2 V = Vo + a*t = 0 Vo = -a*t = -(-3.33)*5.6 = 18.67 m/s.
*September 27, 2014*

**physics**

Incomplete.
*September 27, 2014*

**physics**

Dx = 8.0 m. h = 20 m. Xo = ? m/s. h = 0.5g*t^2 = 20 m. 4.9t^2 = 20 t^2 = 4.082 Tf = 2.02 s. = Fall time. Dx = Xo*Tf = 8.0 m. Xo * 2.02 = 8 Xo = 3.96 m/s.
*September 27, 2014*

**Physics**

Correction: 44m/s * 0.7s = 30.8 m. Lead. d2 = d1 + 30.8 Vo*t + 0.5a*t^2 = 44t + 30.8 20t + 3t^2 = 44t + 30.8 3t^2 - 24t - 30.8 = 0 Use Quad. Formula. t = 9.125 s.
*September 27, 2014*

**Physics**

44m/s * 0.7s = 30.8 m. Lead. d2 = d1 + 14 m. Vo*t + 0.5a*t^2 = 44t + 14 20t + 3*t^2 = 44t + 14 3t^2 - 24t - 14 = 0 Use Quadratic formula. t = 8.55 s.
*September 27, 2014*

**physics**

h = 0.5g*t^2 = 0.9 m. 4.9*t^2 = 0.9 t^2 = 0.1837 Tf = 0.429 s. = Fall time. Tr = Tf = 0.429s. = Rise time. Y = Yo + g*Tr = 0 Yo = -g*Tr = 9.8 * 0.429 = 4.2 m/s. Yo = Vo*Sin53 = 4.2 Vo = 4.2/Sin53 = 5.26 m/s. = The required speed.
*September 27, 2014*

**physics**

Vo = 15m/s @ A Degrees. Xo = 15*Cos A. Yo = 15*Sin A. Dx = Xo*Tf = Xo * 6 = 78 m. Xo = 13 m/s. Xo = 15*Cos A = 13 m/s. 15*Cos A = 13 Cos A = 13/15 = 0.86667 A = 29.93o Yo = 15*Sin29.93 = 7.48 m/s. h = Yo*T + 0.5g*t^2 = 7.48*6 + 4.9*6^2 = 221.3 m.
*September 27, 2014*

**Math**

1. (F-g)(x) = (2x-5) - 4 = 2x - 5 - 4 = 2x - 9. 2. (F-g)(x) = 4 - (2x-1) = 4 - 2x + 1 = -2x + 5.
*September 27, 2014*

**physics**

V^2 = 2g*h = 19.6*5 = 98 V = 9.9 m/s. V^2 = Vo^2 + 2g*h = 0 Vo^2 - 19.6*1.61 = 0 Vo^2 = 31.556 Vo = 5.62 m/s a = (5.62-9.9)/0.027 = -158.5 m/s^2.
*September 27, 2014*

**physics**

The given frequencies appear to be too close together; and the answer is negative. Please check.
*September 27, 2014*

**Science**

Vo = 80km/h = 80000m/3600s. = 22.22 m/s. V = 13km/h = 13000m/3600s. = 3.61 m/s. a = (V-Vo)/t
*September 27, 2014*

**Physics**

a. V = Vo + g*t = 0 + 9.8*2.40 = 23.5 m/s. b. h = 0.5g*t^2 = 4.9*2.40^2 = 28.2 m.
*September 26, 2014*

**physics**

V^2 = Vo^2 + 2g*h Vo = 0 g = 3.7 m/s^2 h = 387 m. Solve for V
*September 26, 2014*

**physics**

m*g = 40kg * 9.8N/kg = 392 N. = Wt. of trolley. Fp = 392*sin20 = 134.1 N. = Force parallel to the hill. F-Fp = m*a F-134.1 = m*0 = 0 F = 134.1 N.
*September 25, 2014*

**physics**

Incomplete.
*September 25, 2014*

**Math conversion**

2.54cm = 1in 1cm = (1/2.54)in Cube both sides: 1cm^3 = (1/16.39)in^3 Multiply both sides by 21: 21cm^3 = 1.281 in^3
*September 25, 2014*

**Physics**

Series circuit: P = I^2 * R The bulb with the highest resistance will receive the most power; and will, therefore, be brighter. Parallel circuit: P = V * I The lowest resistance will receive the most power and will be brighter.
*September 25, 2014*

**Trigonometry**

Circumference = pi*D = 3.14 * 4.5 = 14.13 In. = 1.1775 Ft V=15mi/h * 5280Ft/mi * 6.28Rad/1.1775Ft * 1h/3600s. = 117.3 Rad/s.
*September 25, 2014*

**Physics**

Vo = 33.7m/s[24o] Xo = 33.7*Cos24 = 28 m/s. Yo = 33.7*Sin24 = 13.7 m/s. Tr = -Yo/g = -13.7/-9.8 = 1.40 s. = Rise time. h max = -Yo^2/2g = -(13.7^2)/-19.6 = 9.58 m. Above the bldg. 0.5g*t^2 = 9.58 + 110.8 = 120.4 m 4.9*t^2 = 120.4 t^2 = 24.57 Tf = 4.96 s. = Fall time. Dx = Xo*(...
*September 24, 2014*

**Physics**

The First Object: h = Vo*t + 0.5g*t^2 = 39 m. 54.9*t - 4.9*t^2 = 39 Use Quadratic formula. t = 0.762 s. The 2nd. Object: h = Vo*t + 0.5g*t^2 = 157.9-39 = 118.9 m Vo*0.762 + 4.9*0.762^2 = 118.9 0.762Vo + 2.845 = 118.9 0.762Vo = 118.9 - 2.845 = 116.05 Vo = 152.3 m/s.
*September 24, 2014*

**Physics**

a. X = 1300 m. Y = -880 m. Tan A = Y/X = -880/1300 = -0.67692 A = -34.1o CW = 325.9o CCW. D = X/Cos A = 1300/Cos(-34.1) = 1570 m. [325.9o]. D(1300, -880). b. T = 13min * 60s/min. = 780 s. Vavg = (1300+880)m/780s. = 2.79 m/s.
*September 24, 2014*

**Physics**

Momentum = M1*V1-M2*V2 = 20*80-5*50 = 1350. M1*V + M2*V = 1350 20*V + 5*V = 1350 25V = 1350 V = 54 m/s.
*September 24, 2014*

**physics**

V = Vo + a*t = 0 Vo -0.5*8 = 0 Vo = 4 m/s. Should the distance rolled be 16 m?
*September 24, 2014*

**Math**

See previous post: Tue, 5-12-09, 9:00 PM.
*September 24, 2014*

**system of equations**

X yrs. = John's age today. 5x yrs. = John's mom's age today. 7 years from now: x+7 = John's age. 5x+7 = John's mom's age. 5x+7 = 3(x+7) 5x+7 = 3x+21 2x = 14 X = 7 Yrs. = John's age today.
*September 24, 2014*

**physics**

Vo = 53.8m/s[42o] Xo = 53.8*Cos42 = 40. m/s Yo = 53.8*Sin42 = 36.00 m/s. a. Yo*t + 0.5g*t^2 = 840 m. -36*t + 4.9t^2 = 840 4.9t^2 - 36t - 840 = 0 Use Quadratic formula and get: t = 17.3 s. = Fall time. Dx = Xo*t = 40 * 17.3 = 692 m. b. Y^2 = Yo^2 + 2g*h = 36^2 + 19.6*840 = 17,...
*September 24, 2014*

**physics**

m*g = 7 * 9.8 = 68.6 N. = Wt. of book. Fp = 68.6*sin A = Force parallel to the plank. Fn = 68.6*Cos A = Force perpendicular to the plank. Fs = u*Fn = 0.4*68.6*Cos A Fp-Fs = m*a 68.6*sin A - 0.4*68.6*Cos A = m*0 = 0 68.6*Sin A = 0.4*68.6*Cos A Sin A = 0.4*Cos A Divide both ...
*September 24, 2014*

**Physics**

Q1. a = g = -9.8 m/s^2 = 9.8 m/s^2 Downward. Q2. h = 0.5g*t^2 = 4.9*3^2 = 44.1 m.
*September 23, 2014*

**algebra**

Multiply Eq1 by 1.25 and Eq2 by 0.25 and subtract: 0.3125x + 0.1875y = 3.125 0.3125x - 0.3125y = 1.875 Diff. : 0.5Y = 1.25 Y = 2.5 In Eq1, replace y with 2.5: 0.25x + 0.15*2.5 = 2.5 0.25x = 2.5 - 0.375 = 2.125 X = 8.5
*September 23, 2014*

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