Sunday

April 19, 2015

April 19, 2015

Total # Posts: 20,912

**Typo**

copied your result, should be I CLAIM Beta-subX = -3.20 ft SIN(53.4) = -2.56 Beta-subY = 3.20 ft COS(53.4) = 1.90
*February 24, 2015*

**physics**

Because the angle 53.4 is left from the Y axis, not up from the X axis. They tricked you with the west of north that is left of the Y axis DRAW the picture.
*February 24, 2015*

**physics**

This is right: Alpha-subX (for the x component) Alpha-subX = 81.6 ft * cos(31.7) = 69.426 Alpha-subY (for the y component) Alpha-subY = 81.6 ft * sin(31.7) = 42.878 This is WRONG Beta-subX = 3.20 ft cos(53.4) = 1.907 Beta-subY = 3.20 ft sin(53.4) = 2.569 I CLAIM Beta-subX = -3...
*February 24, 2015*

**physics**

But going west is NEGATIVE x
*February 24, 2015*

**physics**

Yes, exactly BUT THE SECOND ONE was west of north x distance = 69.4 -3.2 sin 53.4 = x y distance = 42.9 + 3.2 cos 53.4 = y d = sqrt (x^2 + y^2) tan of angle north of east = y/x
*February 24, 2015*

**Physics**

the mass is proportional to the number of mols n2/n1 = m2/m1 P1 V1 = n1 R T1 so n1 = P1 V1/R T1 P2 V2 = n2 R T2 so n2 = P2 V2/R T2 n2/n1 = m2/m1 = (P2 V2/P1V1)(T1/T2) 6/4.9 = (P2*2/75*5)(323/273) solve for P2
*February 24, 2015*

**physics**

in one revolution the tire goes 2 pi r = pi D feet = pi (2) feet which is (2 pi/5280)miles (2 pi/5280)n = 60,000 miles (part b) 2 pi n = number of radians (part a)
*February 24, 2015*

**Algebra**

x > y x + y = 6 x - 2 y = 9 ------------subtract 0 + 3 y = -3 y = -1 x = 7
*February 23, 2015*

**algebra**

The volume of anything pointy with straight sides is (1/3) base area * height V = (1/3)(pi)(25)^2 (7.2) same V for second one (1/3)(pi)(25)^2 (7.2)=(1/3)(pi)(15)^2 h so 625 (7.2) = 225 h h = (625/225)(7.2) In fact you never even need pi
*February 23, 2015*

**physics**

If A stopped and it was elastic then the B has the same as A had (1/2)(.55)(v^2)
*February 23, 2015*

**algebra**

Move right five 8.9 * 10^-5 move left two 4.56981 * 10^2 Due to your lack of showing your attempt I can not tell why you were having trouble with this.
*February 23, 2015*

**Science**

.9189189189..... But some of the ice floats above the water. Something must be holding it below water.
*February 23, 2015*

**Electricity and magnetism**

but the force decreases with distance as 1/x^2 F = k/x^2 we want W = integral F dx from x = d1 to x = d2 W = k integral (dx/x^2) = k (-1/x) from x = d1 to x = d2 = k/d1 - k/d2
*February 23, 2015*

**maths**

each year p(y) = .92 p(y-1) when y = 0, p = 5300 when y = 1, p = .92 * 5300 when y = 2, p = .92*.92 * 5300 when y = n, p = .92^n * 5300 think compound negative interest :) p = .92^y * 5300
*February 23, 2015*

**Math**

Yes, any real x except x = 1
*February 23, 2015*

**calculus**

aaaarrrrrgggggghhhhh !!!!
*February 23, 2015*

**calculus**

I will just do two dimensions for demo a) A dot (B+C) = AxBx + Ax Cx + AyBy + AyCy does that equal AxBx+AyBy + AxCx+AyCy Yes, it does b) A X (B+C) = A X (Bx+Cx)i +(By+Cy)j i j k Ax Ay 0 (Bx+Cx) (By+Cy) 0 find determinant [Ax(By+Cy) - Ay(Bx+Cx) ]k k direction of course [ AxBy...
*February 23, 2015*

**physics**

LOL - That same old impulse thing again. find change of momentum = final m v - initial mv (doing only component perpendicular to wall, v = 10 sin 60 inbound v = - 10 sin 60 outbound change in v = 2 * 10 sin 60 Force = change in momentum/time It only acted perpendicular to the ...
*February 22, 2015*

**chemistry**

22.41 - 21.30 = 1.11 mL so 8.7 g/1.11 mL = 7.838 g/mL or g/cm^3 almost 8 times density of water by the way which is how you remember it.
*February 22, 2015*

**ap physics**

I can not see your graph but use the logic from the other problem I just helped you with. F = m a = m dv/dt impulse = integral F dt = final mv - initial m v
*February 22, 2015*

**AP physics**

Force = change in momentum/time = m a when m is constant so Force * time = change of momentum, called impulse impulse = force * time = change of momentum final momentum = .278 (22.4) initial momentum = .278 (-16.2) change = .278 (22.4 - {- 16.2} ) = .278 (38.6) = 10.7 kg m/s (...
*February 22, 2015*

**math**

sure enough :)
*February 22, 2015*

**math**

x [(102 x - 228 )/6] +51 = 200 (102 x - 228 )/6 = 149 102 x - 228 = 894 102 x = 1122 x = 11
*February 22, 2015*

**Calculus**

the extrema of a function are where the derivative is zero or at the ends of the domain concave or convex depends on sign of second derivative at that extreme. If plus, it holds water (minimum). If negative, it sheds water (maximum).
*February 22, 2015*

**physics**

I assume they gave you mu dry and mu wet Ac = v^2/R = v^2/30 inward force needed = m Ac = m v^2/30 max inward force provided = mu m g so v^2 = 30 mu g
*February 22, 2015*

**finite math**

prob of red, white then blue = 4/13 * 6/12 * 3/11 prob of red, blue then white = 4/13 * 3/12 * 6/11 prob of white, red then blue = 6/13 * 4/12 * 3/11 prob of white, blue then red = 6/13 *3/12 * 4/11 prob of blue, red then white =3/13 * 4/12 * 6/11 prob of blue, white then red...
*February 22, 2015*

**Math Help!**

Oh well, number 2 start at 1 for min 1 + 2 + 3 + 4 ..... = 45 arith series (n/2)[2 + (n-1)(1)] = 45 n + (n/2)(n-1) = 45 n + n^2/2 -n/2 = 45 n + n^2 = 90 n^2 + n - 90 = 0 n = [ -1 +/- sqrt(1+360) ]/2 n = 18/2 = 9 check 1 + 2 + 3 + .....9 = 4.5(2+8) = 45 sure enough
*February 22, 2015*

**Physics**

Answer g) first (trick question) F = m a a = 0 so net force on crate = 0 =========================== a) 1 - friction 2 - m g gravity 3 - normal from ramp so three b) gravity, just one c) none are horizontal d)gravity, normal and friction all have vertical components so three e...
*February 22, 2015*

**Physics**

up is + a) gravity force down = weight = -m g = -1210*9.81 = -11870 N b) F is positive up F = m a = 1210(-1.4) F = - 1696 N c)gravity pushing down, helicopter pushing up d)lift is up lift - 11870 = m a = -1696 lift = 11870 - 1696 = 10176 N up
*February 22, 2015*

**Vectors Math**

Your notation is a mystery to me. The magnitude of the projection of A on to A is |A| cos T where T is the angle between A and B but |A| cos T = |A| |B| cos T /|B| which is A dot B /|B| Now we need a unit vector in direction B That is B/|B| so in the end we need A dot B * B /|...
*February 22, 2015*

**Vectors**

"bearing" means what direction you LOOK. "heading" means what direction you point the vehicle. As in: We were heading north when we took a bearing of 90 degrees on a lighthouse east of us.
*February 22, 2015*

**Vectors**

Math teachers do not know navigation English. It drives me crazy. You do not head on a bearing. You sail or fly on a heading. the plane is flying on a heading of 200 (about SSW) at 400 km/h the plane is also moving at 100 km/h southwest which is 180+45 = 225 degrees You can do...
*February 22, 2015*

**Physics**

C = q/V so V = q/C so q1/C1 + q2/C2 + q3/C3 = 58 but q1=q2=q3 becaue where else are the electrons to come from or go to? so 1/C1 + 1/C2 + 1/C3 = 58/ q 10^6 (1/3.83+1/5.89+1/12.9 = 58 /q 10^6 (.508) = 58 / q q = (58/.508)10^-6 V = (58/.508)/3.83 = 29.8 volts
*February 21, 2015*

**College Physics**

900(1.0)+ Tright(3) so Tright = 300 N Tright + Tleft = 900 so Tleft = 600 N
*February 21, 2015*

**college physics**

been there, done that, see above
*February 21, 2015*

**Physics**

C = q/V so V = q/C so V = qA/CA = qB/CB and E = (1/2) q V = (1/2) C V^2 5.7*10^-5 = (1/2)(17*10^-6)V so V = 6.71 volts then 6.71 = (qB/6.9)10^6
*February 21, 2015*

**physics**

A steel ball with a mass of 0.65 kg is swinging in a circle with a radius of 1.3 meters at a speed of 17m/s. What is the centripetal force?
*February 20, 2015*

**Physics**

3.6m/5 = .72 square root .72= .8485*24m/sec=20.36m it will travel 20.36 meters
*February 20, 2015*

**Physics**

A baseball is thrown horizontally from a height of 3.6 meters at a speed of 24 m/sec. How far will it travel along the ground?
*February 20, 2015*

**Math Ms Sue**

By the way 4 * 6 = 6 * 4 That is called "Commutative property of multiplication" which is grade three this week for my grandson's class.
*February 18, 2015*

**Math Ms Sue**

area of rectangle = length times width 4 * 6 or using your notation 4 x 6
*February 18, 2015*

**physics**

Sure looks like zero to me. 2 sin 30 = 1
*February 18, 2015*

**Physics**

normal force = m g cos 27.7 friction force up slope = mu m g cos 27.7 gravity component down slope = m g sin 27.7 so m (1.25) = m g sin 27.7 - mu m g cos 27.7 mu g cos 27.7 = g sin 27.7 - 1.25 solve for mu
*February 18, 2015*

**english**

because
*February 18, 2015*

**math/Do not understand**

These picks are independent. Picking a male student does not affect the following pick of a female student. Therefore the answer is simply the product of the two probabilities. 153 + 357 = 510 males male probability = 153/510 = .3 145 + 355 = 500 females female probability = ...
*February 18, 2015*

**Physics**

omega = radians/s = 2 pi/.5 = 4 pi Ac = omega^2 R = (4 pi)^2 * .1 F = m Ac = .012 (4 pi)^2 (.1) increases as omega^2 so 2^2 = 4 times
*February 18, 2015*

**Physics**

the total = 14.7 so 3.5 + 1.4 + V3 = 14.7 R3 = V3/(7*10^-3)
*February 18, 2015*

**physics**

Ke = .5 m v^2 .5 (7)(2.15)^2 = .5 (.0024) v^2 v^2 = (7)(2.15)^2/.0024
*February 17, 2015*

**physics**

(a) 150 * 5.5 Joules (b) no acceleration so work done by friction = 150 * 5.5 mu m g *5.5 = 150 * 5.5 mu = 150/(45*9.81)
*February 17, 2015*

**physics**

east distance = x = 4 + 2 cos 50 south distance = y = -2 sin 50 d = sqrt ( x^2 + y^2 )
*February 17, 2015*

**Math**

.015(500) + .01 (241.23)
*February 17, 2015*

**math**

S(5) = 125 -125 + 4 = 4 v = 3 t^2 - 10 t v(5) = 75 - 50 when is v = 0? 3 t^2 - 10 t = 0 = t(3 t - 10) t = 0 or t - 10/3 a = 6 t - 10 a(2) = 12 - 10 = 2
*February 17, 2015*

**Calculus**

he said at (0,0) the slope is 2 That is a line through the origin with slope = 2 y = 2 x + 0
*February 17, 2015*

**Business Math**

paid 5.50 dollars for 100 dollars that is 100(5.50/100) = 5.5 percent in two weeks or 2.75 percent per week 2.75 * 52 = 143 percent per year. Which is huge!
*February 16, 2015*

**Algebra typo ???**

b a^2 This question means nothing to me, sorry.
*February 16, 2015*

**phyic**

G = 6.67 * 10^-11 N m^2/Kg^2 Sun mass = 1.99 * 10^30 Kg Jupiter mass = 1.89 * 10^27 Kg d= 7.78 * 10^11 m F = G Msun Mjup / d^2 =[6.67*1.99*1.89/60.5]10^[-11+30+27-22] = .141 * 10^24 = 1.41 * 10^23 Newtons
*February 16, 2015*

**math**

You fixed the speed at 5 d = 5 t distance, d, depends on how long you walk ,t We are assuming that the number of credits earned is a function of (dependent on) age age is independent credits is dependent There is no function implied here, in fact there might be multiple values...
*February 16, 2015*

**math**

51 = 3 m
*February 13, 2015*

**Physics**

work = charge * voltage work in Joules charge in Coulombs voltage in Volts 133/3 = 44 1/3 Volts
*February 13, 2015*

**Physics**

Do not understand your notation. Do you mean 2.13 * 10^8 Volts ???? anyway energy in Joules = potential in Volts * charge in Coulombs
*February 13, 2015*

**kayli**

molecules
*February 13, 2015*

**math**

All three of us got the same answer.
*February 13, 2015*

**math**

10 ft/min (60 min/1h)(1 mi /5280 ft) = 600/5280 mi/h = 0.1136 mi/h
*February 13, 2015*

**pre cal 11**

You are welcome.
*February 13, 2015*

**pre cal 11**

If tn = -4 + (n-1)6 then tn = -4 + 6 n - 6 or tn = 6 n - 4 -6 which is 6 n - 10 sure enough
*February 13, 2015*

**pre cal 11**

There are 7 posts including the two end ones. That means six equal spaces between posts 42/6 = 7 meters (note, number of spaces = number of posts - 1)
*February 13, 2015*

**Physics**

28.5 cm/s * 2.88 cm^2 = 82.1 cm^3/s volume flow rate so mass flow rate is 82.1 cm^3/s * 1.03 g/cm^3 = 84.5 g/s
*February 13, 2015*

**maths**

A work/day = 1/16 B work/day = 1/12 2(1/16) + x(1/16 +1/12) = 1
*February 13, 2015*

**Physics Dynamics**

work done against friction = Initial PE - final Ke = Force of friction * distance down slide = mu * normal force * distance Now where is your work?
*February 12, 2015*

**Math**

ds/dt = v = -4 (2t) /t^4 = -8/t^3 if t = a v = -8/a^3 if t = 1 v = -8/1 = -8 if t = 2 v = -8/8 = -1 if t = 3 v = -8/27
*February 12, 2015*

**Algebra 1**

6 a + 2 s = 40 5 a + 12 s = 85 multiply first one by 6 36 a + 12 s = 240 5 a + 12 s = 85 ------------------ subtract 31 a = 155 a = $5 now find s
*February 12, 2015*

**Physics**

so the magnitude is 3.31 kg m/s
*February 12, 2015*

**Physics**

-29 m/s - (+29 m/s) = -58 m/s velocity change change in momentum = -.057(58) kg m/s
*February 12, 2015*

**Physics**

Ac = v^2/R = 100/20 = 5 m/s^2 so F = m g + 5 m = (9.81+5)m = 14.81 m so F = 14.81*85 = 1258 Newtons f = change in momentum / time change in momentum = 85*10 = 850 kg m/s time = distance/average speed = 1.5/5 = .3 seconds so f = 850 kg m/s / .3 s = 2833 kg m/s^2 = 2833 Newtons
*February 12, 2015*

**math**

(1/2) x = 3 x = 6
*February 12, 2015*

**Math**

HE HAD 280 dollars. That is the answer. It is not a fraction.
*February 12, 2015*

**Math**

he started with x he spent 3/7 of x then he had 4/7 of x left he then gave his sister 1/4 of 4/7 of x so he was left with 3/4 of 4/7 of x that is 120 so 3/4 * 4/7 * x = 120 3/7 * x = 120 x = 40*7 = 280 =========================== NOW spend 3/7 * 280 = 120 280 - 120 = 160 left ...
*February 12, 2015*

**Math**

Look at this simpler problem: http://www.jiskha.com/display.cgi?id=1423783632
*February 12, 2015*

**Math**

He spent 3/7 which left him with 4/7 !!! 7/7 - 3/7 = 4/7 then he gave away 1/4 of his 4/7 1 - 1/4 = 3/4 so he is left with 4/7 * 3/4
*February 12, 2015*

**math**

HUH ? 120.25 + (7/28)^(3/7) ??? but 7/28 = 1/4 = .25 120.25 + .25^.42857 ??? 120.25 + 0.55 = 120.80
*February 12, 2015*

**Physics**

You have to tell us the angles from vertical or horizontal or what. if from horizontal T1 cos 45 = T2 cos 30 .707 T1 = .866 T2 T2 = .816 T1, so T1 is the one that will break m g = T1 sin 45 + T2 cos 30 m g = .866 T1 + .866 (.816) T1 m g = .866 T1 + .707 T1 = 1.57 T1 m g = 1.57...
*February 12, 2015*

**Math**

I am getting a bit bored with this question as well.
*February 12, 2015*

**Math**

he was left with 4/7 he gave 1/4 of the 4/7 to his sister so he was left with 3/4 of the 4/7 so (3/4)(4/7)x = 120 (3/7) x = 120 x/7 = 40 x = 280
*February 12, 2015*

**math**

1 - 3/7 = 4/7 is remainder (4/7) x - 3 = 120
*February 12, 2015*

**TYPO ???**

5 seconds up, 5 seconds down do vertical problem first with Vi = initial velocity component up v = Vi - g t at top v = 0 0 = Vi - 10 t but t = 5 seconds so Vi = 50 m/s IF YOU LAUNCH AT 10 m/s, YOU CAN NOT STAY IN THE AIR TEN SECONDS!
*February 12, 2015*

**Science**

If there are no mutations, there are no changes with generations, no adaptation of beak lengths or anything.
*February 12, 2015*

**Science**

You are welcome.
*February 12, 2015*

**Science**

n = 2 , 3, 4, 5, 6 ,7 ..... n^2 = 4 , 9 , 16, 25,...... 1/n^2 = 1/4 , 1/9 , 1/16 .....
*February 12, 2015*

**Science**

so did I :)
*February 12, 2015*

**Science**

1/n^2
*February 12, 2015*

**math**

100(3/4) = 300/4 = 75
*February 12, 2015*

**math**

sorry, slope intercept form is y = -(1/2) x + 1/2
*February 12, 2015*

**math**

2 y = -x + 8 y = -(1/2) x + 4 so slope = -1/2 -2 = -(1/2) 5 + b -2 = -2.5 + b b = .5 = 1/2 so y = -(1/2) x + 1/2 2 y + x = 1
*February 12, 2015*

**Math**

x in 1900 y in 2015 x = .64 y so y = 1.56 x so y now is 156 percent of x which is an increase of 56 percent
*February 12, 2015*

**Math**

(4/7)(3/4) x = 120
*February 12, 2015*

**Physics**

d = (1/2) g t^2 6.9 = 4.9 t^2
*February 12, 2015*

**Physics**

horizontal x = 100 + 35 cos 35 vertical y = 35 sin 35 or sqrt(x^2+y^2) at tan^-1(y/x) above x axis
*February 12, 2015*

**Physics**

There is no force on the ball after it its release so it continues at 4,000 km/s while the ship accelerates away from it. Therefore: -6 m/s^2 Think, how does your head move when you accelerate a car as opposed to driving straight at constant speed.
*February 12, 2015*

**math**

3/2 is bigger than 1 4/9 = 13/9
*February 12, 2015*

**linear algebra**

well, we agree this time :)
*February 12, 2015*