Thursday

September 29, 2016
Total # Posts: 12,063

**Physics**

Vo = 21 m/s. Vf = Vo + a*t = 21 + 1.6*6.8 = 31.9 m/s.

*October 6, 2015*

**Physics**

Vo = 72m/s[Ao]. Xo = 46 m/s. Xo = 72*Cos A = 46. Cos A = 46/72 = 0.63889. A = 50.3o

*October 6, 2015*

**Physics**

Vo = 24.3 m/s.[29o] Yo = 24.3*sin29 = 11.8 m/s. Yf = Yo + g*Tr = 0 at max h. 11.8 - 9.81Tr = 0. Tr = 1.20 s. = Rise time. h = Yo*Tr + 0.5g*Tr^2. g = -9.81 m/s^2.

*October 6, 2015*

**science**

Vo = 2 m/s. t = 4 s. a = 3 m/s^2. d = Vo*t + 0.5a*t^2.

*October 6, 2015*

**math**

Correction: V = 69.3 Ft/s.

*October 6, 2015*

**math**

1. h = 75 Ft ?. V = Sqrt(64*75) = Sqrt(4800) = 69.3Ft^2. 2. Sqrt(N) = N^(1/2). Curt(N) = N^(1/3).

*October 6, 2015*

**Physics**

Vo = 15 m/s?. V1 = 15 m/s. Vf = Vo + g*Tr = 0 at max h. 15 - 9.8*Tr = 0. Tr = 1.53 s. = Rise time. Tf = Tr = 1.53s. = Fall time. T = Tr+Tf = 1.53 + 1.53 = 3.06 s.

*October 6, 2015*

**Physics**

Vo = 15m/s[39o]. Yo = 15*sin39 = 9.44 m/s. Y = Yo + g*Tr = 0 @ h max. 9.44 - 9.8Tr = 0. Tr = 9.44/9.8 = 0.96 s. = Rise time. Tf = Tr = 0.96 s. = Fall time. T = Tr+Tf = 0.96 + 0.96 = 1.92 s.

*October 6, 2015*

**physics**

1. Vo = 55m/s[52o]. Xo = 55*Cos52 = 33.9 m/s. Yo = 55*sin52 = 43.3 m/s. h = Yo*t + 0.5g*t^2 = g = -9.8 m/s^2. h = ?. 2. Range = Vo^2*sin(2A)/g. Vo = 22 m/s. A = 30o. g = 9.8 m/s^2.

*October 5, 2015*

**physics**

C = C1*C2/(C1+C2) = 3*6/(3+6) = 2 uF. Ct = C + C3 = 2 + 4 = 6 uF. Total Energy = 0.5C*E^2 = 0.5*6*6^2 = 108 J.

*October 5, 2015*

**Physics**

Vf = Vo + a*t = 0. 3.08 + a*0.21 = 0. 0.21a = -3.08. a = -14.7 m/s^2. F = M*a.

*October 5, 2015*

**Physics**

Tr = 23.2/2 = 11.6 s. = Rise time. Vf = Vo + g*Tr = 0. 16 + g*11.6 = 0. 11.6g = -16. g = -1.38 m/s^2.

*October 5, 2015*

**Physics**

All angles are CCW from +x-axis. Vp + Vw = 420km/h[97o]. 420[90o] + Vw[225o] = 420[97o] 420i + Vw*Cos225+Vw*sin225 = 420*Cos97 +420*sin97 = 420i - 0.707Vw - i0.707Vw = -51.2 + 417i = -51.2 -3i. 0.707Vw (-1-1i) = -51.2 - 3i. 0.707Vw(1.41[225o]) = 51.3[183.4o]. Vw[225o] = 51.3[...

*October 4, 2015*

**PHYSICS**

X = -47.9 N. Y = 81.2 N. Q2. a. F3 = Sqrt(X^2 + Y^2) b. Tan A = Y/X = 81.2/-47.9 = -1.69520. A = -59.5o = 59.5o N. of W. Direction = 59.5o S. of E.

*October 4, 2015*

**PHYSICS**

See previous post: Sat, 8-15-15, 7:29 AM

*October 4, 2015*

**PHYSICS**

Wc = M*g. Fn = Mg*Cos15. a. Fn/Wc = Mg*Cos15/Mg = Cos15 = 0.966. b. Fn/Wc = Mg*Cos32/Mg = Cos32 = 0.848.

*October 4, 2015*

**PHYSICS**

Wb = M*g = 50.5 * 9.8 = 494.9 N. = Normal force, Fn. Fs = u*Fn = 0.624 * 494.9 = 308.8 N. = Force of static friction. Fk = 0.364 * 494.9 = 180.1 N. a. F-Fs = M*a. F-308.8 = M*0 = 0 F = 308.8 N. b. F-Fk = M*a. F-180.1 = M*0 = 0. F = 180.1 N.

*October 4, 2015*

**physics**

-16t^2 + 100t + 140 = 200. -16t^2 + 100t - 60 = 0. Divide by 4: -4t^2 + 25t - 15 = 0. Use Quadratic Formula. Solutions: T1 = 0.67 s, T2 = 5.8 s.

*October 4, 2015*

**physics**

h = 0.5g*t1^2 = 22 m. g = 9.8 m/s^2. t1 = ?. 1.4m/s * t2 = 4 m. t2 = ?. T = t1 + t2.

*October 4, 2015*

**Physics**

Vr = 120km/h[0o] + 50km/h[202o,CCW]. Vr = 120+50*Cos202 + i50*sin202 = 120 - 46.4 - 18.7i = 73.6 - 18.7i, Q4. Vr = 73.6 - 18.7i = 76[-14.2o] = 76km/h[14.2o] S. of E.

*October 4, 2015*

**Physics**

See Related Questions: Fr1, 10-17-14, 9:38 PM.

*October 4, 2015*

**Algebra**

a. Scale = 30Ft/6in = 5 Ft/in. 0r 1in = 5 Ft.

*October 4, 2015*

**Physics**

a. F = M*g = 80 * 9.8 = 784 N. b. F-784 = M*a. F-784 = 80*2 = 160. F = 944 N. c. F-784 = M*a. F-784 = M*0 = 0. F = 784 N. d. F-784 = M*a. F-784 = 80*(-1.5). F-784 = -120. F = 664 N.

*October 4, 2015*

**Physics**

Tr = 6/2 = 3 s. = Rise time. Vf = Vo + g*Tr = 0 @ max h. Vo - 9.8*3 = 0. Vo = 29.4 m/s.

*October 4, 2015*

**Physics**

1. X = 10 mi/h. Y = 80 mi/h. Vr = Sqrt(X^2 + Y^2). 2. Same Procedure as #1. 3. Vr = Vp + Vw = 80 + 10 = 90 mi/h. 4. Vr = Vp + Vw = 80 + (-10) = 70 mi/h.

*October 4, 2015*

**Physics**

Vo = 20m/s[40o]. Xo = 20*Cos40 = 15.3 m/s. Yo = 20*sin40 = 12.9 m/s. Dx = Xo*t = 15.3m/s * 2.55s. = 39 m. h = Yo*Tr + 0.5g*Tr^2 Tr = 2.55/2 = 1.275 s. = Rise time. g = -9.8 m/s^2.

*October 4, 2015*

**physics**

F = M*a = 40 * 5*9.8 = 1960 N.

*October 3, 2015*

**PHYSICS**

Fr = 3N[0o] + 4N[90o] + 12N[180o] = 3 + 4i -12 = -9 + 4i, Q2. Fr = Sqrt ((-9)^2 + 4^2)

*October 3, 2015*

**science**

See previous post: Sat, 10-3-15, 12:51 PM.

*October 3, 2015*

**wcience**

a. M*2V/M*V = 2. b. 0.5M*V/M*V = 0.5 = 1/2. c. 3M*3V/M*V = 9.

*October 3, 2015*

**science**

h = 0.5g*t^2

*October 3, 2015*

**physical science**

d = V*T = 3*10^8m/s * T = 3.5*10^5 m. T = ?.

*October 2, 2015*

**physics**

a. Yf^2 = Yo^2 + 2g*h. Yo = 0. g = 9.8 m/s^2. h = 1013 m. Yf = ?. Vf = Sqrt(Xo^2 + Yf^2), Xo = 123 m/s. b. Tan A = Yf/Xo.

*October 2, 2015*

**Physics acceleration**

Vf = 91.4mi/h * 1600m/mi * 1h/3600s. = m/s. a = (Vf-Vo)/t = m/s^2. Vo = 0. a = ?

*October 1, 2015*

**physics**

Fa+Fb = M*a = 12.3 * 0.443 = 5.45 N. Fa-Fb = 12.3 * 0.280 = 3.44 N. a. Fa + Fb = 5.45. Fa - Fb = 3.44. Sum: 2Fa = 8.89. Fa = 4.45 N. b. Fa + Fb = 5.45 4.45 + Fb = 5.45. Fb = 1.00 N.

*October 1, 2015*

**Physics help!!**

a = (Vf-Vo)/t = (-25-49)/0.0022 = -33.64 m/s^2. F = M*a. Note: The force will be negative, because it opposes the initial motion.

*October 1, 2015*

**Physics**

See previous post: Fri, 9-11-15, 12:45 PM.

*October 1, 2015*

**physics**

See Related Questions: Tue, 4-29-14, 1:34 PM.

*October 1, 2015*

**Physics**

h = 0.5g*t^2 = 0.024 m. 4.9*t^2 = 0.024. t = ? Dx = Xo^t = 50 m. Xo*t = 50. Xo = ?. 6

*October 1, 2015*

**Physics**

d1 = V1*t = 14m/s * 3.5s. = 49 m. Head-start. a. d2 = 49 + V1*t. 0.5a*t^2 = 49 + V1*t. 0.5*4*t^2 = 49 + 14*t. 2t^2-14t-49 = 0. Use Quadratic Formula. t = 9.56 s. b. d = 0.5a*t^2.

*October 1, 2015*

**Physics**

See Related Questions: Thu, 1-31-13, 2:29 AM.

*October 1, 2015*

**physics**

X = 172*Cos23. Y = 172*sin23.

*October 1, 2015*

**physics**

X = 18 * Cos13.

*October 1, 2015*

**physics**

X = 5.2 m. Y = 37.8 m. Disp. = Sqrt(X^2 + Y^2). Tan A = Y/X = 37.8/5.2 = 7.26923. A = 82.2o N. of E. = 7.8o E. of N.

*October 1, 2015*

**physics**

Incomplete.

*October 1, 2015*

**physics**

Y = 37.8 m. X = 5.2 m. Disp. = Sqrt(X^2 + Y^2) =

*October 1, 2015*

**Pre-Algebra**

(1/5)^9 = 1/5^9 = 5^-9.

*October 1, 2015*

**conversion**

2kw = 2000 W. hp = 2000/746.

*October 1, 2015*

**conversion**

20 Watts = 20 J/s.

*October 1, 2015*

**PHYSICS**

M1*V1 + M2*V2 = M1*V + M2*V. 5000*15 + 1000*(-30) = 5000V + 1000V. V = ?.

*October 1, 2015*

**PHYSICS**

Density = 100g/600cm^3 = g/cm^3.

*October 1, 2015*

**PHYSICS**

F = 155N/m * 0.05m = 7.75 N.

*October 1, 2015*

**physics**

a = (Vf-Vo)/t = (-4.1-2.1)/0.36 = -17.2 m/s^2. a. F = M*a = 0.19 * (-17.2) = -3.27 N. b. Direction = West. c. a=(-4.1i-2.1)/0.36=(4.61[243o]/0.36 = 12.8 m/s^2[243o]. F = M*a = 0.19 * 12.8[243o] = 2.43N.[243o] d. Direction = 243o CCW.

*October 1, 2015*

**physics**

a = (Vf-Vo)/t = (36-5.5)/0.0316 = 965.2 m/s^2. d = Vo*t + 0.5a*t^2 = 5.5*0.0316 + 0.5*965.2*0.0316^2 = 0.656 m.

*September 30, 2015*

**math**

3(x-2) + 4 > 2(2x-3). 3x-6 + 4 > 4x-6. 3x-4x > -6 + 2. -x > -4. X < 4. 1. X => 45 min. 2. X =< 2 hrs. 3. $8500 =< X < $12,000.

*September 30, 2015*

**math**

d = 6mi * 5,280Ft/mi * 1yd/3Ft + 551yds = 11,111 yds. d = 11,111yds. * 3Ft./yd. * 1m/3.3Ft. = 10,100.9 m.

*September 30, 2015*

**Physics**

See previous post: Mon, 9-28-15, 9:46 PM

*September 29, 2015*

**Physics**

225o = 180 + 45o. So the vector is 45o below West. Therefore, it will point to the left and downward at an angle of 45o. The three vectors can also be drawn from the origin.

*September 29, 2015*

**PHYS 101**

Wb = M*g = 1.70 * 9.8 = 16.7 N. Fp = 16.7*sin27.4 = 7.67 N. = Force parallel to the incline. a. a = Fp/M = 7.67/1.70 = 4.51 m/s^2. b. PE = Mg*h = 16.7*0.485 = 8.08 J. KE = 0.5M*V^2 = 8.08. 0.85*V^2 = 8.08. V^2 = 9.51. V = 3.08 m/s. c.

*September 29, 2015*

**math help**

Y = 3x^2-6x-9 = 0. A*C = 3 * -9 = -27. sum = 3 + (-9) = -6 = B. 3x^2 + (3x-9x) - 9 = 0. Form two factorable binomials: (3x^2+3x) - (9x+9) = 0. 3x(x+1) - 9(x+1) = 0. (x+1)(3x-9) = 0. x+1 = 0, X = -1. 3x-9 = 0, 3x = 9, X = 3. Intercepts = -1, and 3.

*September 29, 2015*

**welkin**

Wb = M*g = 50 * 9.8 = 490 N. = Normal force, Fn. Fk = u*Fn = 0.2 * 490 = 98 N. Work = Fk*d = 98 * 1 = 98 J.

*September 29, 2015*

**Physics**

a. d1 + d2 = 30 m. 0.5a1*t^2 + 0.5a2*t^2 = 30. 0.5*0.49*t^2 + 0.5*0.43*t^2 = 30. t = ?. b. d1 = 0.5a1*t^2.

*September 29, 2015*

**Physics**

a = (Vf-Vo)/t = (6.20-0)/3.56. d = 0.5a*t^2.

*September 29, 2015*

**physics**

Vc + Vb = 6 + 10i = 11.7km/h[59o] CCW. = 31o E. of N. Boat should sail 31o W. of N.

*September 29, 2015*

**Physics Projectile Motion**

See previous post: Mon, 9-28-15, 10:47 PM.

*September 29, 2015*

**Advanced functions**

No. Going twice as far does not change the braking distance if the initial velocity(Vo) remains constant over that distance.

*September 29, 2015*

**Physics Kinematics.**

Xo = 21 m/s. Yo = 16 m/s. a. V = Vo = Sqrt(Xo^2 + Yo^2). b. Y = Yo + g*Tr = 0. 16 - 9.8*Tr = 0. 9.8Tr = 16. Tr = 1.63 s. = Rise time. Tf = Tr = 1.63 s. Tr+Tf = 1.63 + 1.63 = 3.26 s. = Time in air. c. h = 0.5g*Tf^2 = 4.9*1.63^2 = 13 m.

*September 28, 2015*

**Physics 2D Kinematics**

Incomplete.

*September 28, 2015*

**Physics**

Tb + Ts = 2.5 s. Ts = 2.5-Tb. d = Vs*(2.5-Tb) = 16.5 m. 340*(2.5-Tb) = 16.5. 850-340Tb = 16.5. 340Tb = 833.5. Tb = 2.45 s. = Time of the ball. d = Vb*Tb = 16.5. Vb*2.45 = 16.5. Vb = 6.73 m/s.

*September 28, 2015*

**Physics**

Vf = Vo + a*t. Vo = 8.1 m/s. a = 2.8 m/s^2. t = 5.3 s. Vf = ?

*September 28, 2015*

**math**

10^5cal./s * 10s. = 10*10^5 cal. = 1 Million calculations.

*September 28, 2015*

**Physics**

See previous post: Mon. 9-28-15, 3:51 PM.

*September 28, 2015*

**Physics**

X = -4 km. Y = -3.0 km. Q3. Tan A = Y/X = -3/-4 = 0.750 A = 36.9o S of W. = 216.9o CCW. = Direction. Disp. = X/Cos216.9 = -4/Cos216.9=5.0 km.

*September 28, 2015*

**Physics**

Disp. = 48.1*sin15.5 =

*September 28, 2015*

**2nd Law Physics**

A = (180-107)/2 = 36.5o Above the hor. F = 2.31/2 = 1.16 N., each half. sin36.5 = F/T = 1.16/T. T = 1.16/sin36.5 = 1.94 N., each half.

*September 28, 2015*

**physics**

a. distance = 12 + 19 + 12 = 43 km. b. Disp. = 12i + 19 - 12i = 19 km, East.

*September 28, 2015*

**math**

5. P = Po(1+r)^n. Sem1-annually: Po = $7,000. r = (5%/2)/100% = 0.025 = Semi-annual % rate expressed as a decimal. n = 2Comp./yr. * 5yrs. = 10 Compounding periods. P = 7000 * (1.025)^10 = $8960.59. Quarterly: r = (5%/4)/100% = 0.0125 = Quarterly % rate expressed as a decimal. ...

*September 28, 2015*

**math**

d = (70/55)^2 * 79 = 128 Ft.

*September 28, 2015*

**Math**

True or False. 4. -11^2 = -11 * -11 = 121. Simplify. 4.24d^18. 7. Not sure. 8. Not sure.

*September 28, 2015*

**math**

a contractor's crew can frame 3 houses in a week. how long will it take them to frame 54 houses if they frame the same number each week?

*September 27, 2015*

**Physics**

Vo = 12.5m/s[53.1o]. Xo = 12.5*Cos53.1 = 7.51 m/s. Yo = 12.5*sin53.1 = 10.0 m/s. A. h = ho + -(Yo^2)/2g=75 + 10^2/19.6 = 80.1 m. Above gnd. Y = Yo + g*Tr = 0. Tr = -Yo/g = -10/-9.8 = 1.02 s. = Rise time. 0.5q*Tf^2 = 80.1 m. 4.9Tf^2 = 80.1. Tf^2 = 16.34. Tf = 4.04 s. = Fall ...

*September 27, 2015*

**physics**

10 + 5[60o] + F = 0. 10 + 5*Cos60 + i5*sin60 + F = 0. 10 + 2.5 + 4.33i + F = 0. 12.5 + 4.33i + F = 0. F = -12.5-4.33i = 13.2N[W19.1oS]

*September 27, 2015*

**physics**

Disp. = 30i + 40 = 50m[36.9o]. dist. = 30 + 40 = 70 m.

*September 27, 2015*

**physics**

D = -9 + 17i + 46 = 37 + 17i. X = 37yds, Y = 17 yds. D = Sqrt(X^2 + Y^2)

*September 27, 2015*

**Science**

W = F*d = M*g * d.

*September 27, 2015*

**math**

An excellent explanation, Allyson!

*September 27, 2015*

**physics**

F = 10N.[0o] + 20[60o] = 10 + 20*Cos60 + i20*sin60 = 10 + 10 + 17.3i = 20 + 17.3i = 26.5N.[40.9o].

*September 27, 2015*

**Physics**

V = a*t = 15 * 6 = 90 Ft/s.

*September 27, 2015*

**math**

Jose's age = X yrs. Valerie's age = Y yrs. Eq1: X + Y = 78. 9 yrs. ago: Jose's age: x-9 yrs. Valerie's age: y-9 yrs. x-9 = 3(y-9). x-9 = 3y-27. Eq2: x - 3y = -18. Subtract Eq2 from Eq1: Difference: 4y = 96. Y = 24 = Valerie's current age. X + 24 = 78. X = ...

*September 27, 2015*

**math**

Esmeralda = X yrs. old. Gregory = x+2 yrs. old. In 5 years: Esmeralda = x+5 yrs. old. Gregory = x+2 + 5 = x+7 yrs. old. x+5 + x+7 = 42. 2x + 12 = 42. X = 15 = Esmeraldas' current age.

*September 27, 2015*

**maths**

X boys. 3x/7 girls. x + 3x/7 = 30. 7x + 3x = 210. 10x = 210. X = 21.

*September 27, 2015*

**science**

h = 0.5g*t1^2 = 500 m. 5t1^2 = 500. t1^2 = 100. t1 = 10 s. = Fall time. h = Vs*t2 = 500. 340*t2 = 500. t2 = 1.47 s. To travel 500 m. t1+t2 = 10 + 1.47 = 11.47 s. To hear the sound of the stone.

*September 27, 2015*

**Phy**

Wb = M*g = 3.09 * 9.8 = 30.3 N. Fn = 30.3 - 13.7*sin23 = 24.9 N. = Normal. a. a = 13.7*Cos23/3.09 = 4.08 m/s^2.

*September 26, 2015*

**Physics**

F = 10.3i + 19.5 - 15.2i = 19.5 - 4.9i. X = 19.5, Y = -4.9. F = Sqrt(X^2 + Y^2)=Sqrt(19.5^2+4.9^2) = 20.1 N. a = F/M = 20.1/4.06 = 4.95 m/s^2. Note: The direction(angle) is not required.

*September 26, 2015*

**physics**

All angles are CCW from the +x-axis. D = 3.6m[90o] + 2.8[45o] + 2.2[211o]. X = 3.6*Cos90 + 2.8*Cos45 + 2.2*cos211 = 0 + 1.98 - 1.89 = 0.09 m. Y = 3.6*sin90 + 2.8*sin45 - 2.2*sin211 = 3.6 + 1.98 - 1.13 = 4.45 m. D = Sqrt(X^2 + Y^2).

*September 25, 2015*

**math**

See previous post: Fri, 9-25-15, 11:35 AM.

*September 25, 2015*

**math**

20-year fixed: P = Po*r*t/(-(1+r)^-t). Po = 35000*0.95 = $33,250. r = (7.5%/12)/100% = 0.00625 = Monthly %rate expressed as a decimal. t = 20yrs. * 12mo./yr. = 240 Months. P1 = 33,250*0.00625/(1-1.00625^-240) = $64,286.34. I = P1-Po=64,286.34-33,250=$31,036.34. 30-year fixed...

*September 25, 2015*

**physics**

V = Vo + g*Tr = 0. Tr = -Vo/g = -7.5/-9.81 = 0.77 s. = Rise time. Tf = Tr = 0.77 s. = Fall time. V = Vo + g*Tf. Vo = 0. g = 9.81. V = ?.

*September 25, 2015*

**physics**

V^2 = Vo^2 + 2g*h. Vo = 0. g = 3.7. h = 323 m. V = ?.

*September 25, 2015*

**physics**

See previous post: Fri, 9-25-15, 7:13 AM

*September 25, 2015*