Tuesday

August 30, 2016
Total # Posts: 26,839

**Calculus**

well, any old plane that is not parallel to the other two will intersect both at a point along the lines of intersection of those planes. The line of intersection will be parallel to the cross product of or two normals i j k 1 1 3 1-1 2 Find a plane that has that line of ...
*July 8, 2016*

**Got to be kidding**

Due to bending in a beam? Due to weight of mass hanging from ceiling by string? Due to compression sound wave in steel bar? Due to cooling of same bar while ends are fixed? etc etc etc etc ........
*July 7, 2016*

**Physics**

force = m g = 8 (9.81) work = potential energy gained = m g h = 8 (9.81)(12) power = work/time = 8 (9.81)(12)/15 If for some incomprehensible reason you really ant power/force, divide 12/15
*July 7, 2016*

**Maths**

amount = original * (1+r)^t 3 = (1+r)^t ln 3 = t ln (1+r) t = ln 3 / ln(1+r) r = .09 t = ln 3 / ln(1.09) t = 1.0986 / .086178 t = 12.74 years ====================== check 3 = 1 * 1.09^12.74 ?????? 3 = 2.997 yes that will do
*July 7, 2016*

**Physics**

u = horizontal speed = 73/3 = 24.3 m/s falls 8 meters in 3 seconds h = Hi + Vi t - 4.9 t^2 0 = 8 + 3 Vi - 9(4.9) Vi = 12 m/s upward speed at tree top of 8 m so let's find the top above that tree v = Vi -9.81 t 0 = 12 - 9.81 t t = 1.22 seconds rising above tree so h at top ...
*July 5, 2016*

**Physics**

find ke before child jumps (1/2)I omega^2 find new I (which you did already) find new omega (which you did already) Find new ke = (1/2) Inew (omega new)^2 now work done = new ke - old ke I went up a little but omega went down so I suspect the work will be negative In other ...
*July 5, 2016*

**been there, done that**

http://www.jiskha.com/display.cgi?id=1467694862
*July 5, 2016*

**Physics**

p = m v Ke = (1/2) m v^2
*July 5, 2016*

**Physics**

Force * time = change of momentum T (7*10^-4) = 2 * 6
*July 5, 2016*

**Physics**

impulse = change of momentum = force * time
*July 5, 2016*

**Physics**

Power * time = change in energy 20 P = m g h = 1800 * 9.81 * 15
*July 5, 2016*

**Physics**

(1/2) m v^2 = m g (45-5) v^2 = 2 (9.81)(40) --------------------------------- Second question has no real answer unless we assume that the potential energy is zero at the ground level. ONLY changes in potential have meaning,and you must always define a base If we ASSUME U = 0 ...
*July 5, 2016*

**Physics**

Maybe assume they both take the same time to stop when they crash into you Force * time = change in momentum for duck Force * time = 2.8 * .35 for goose Force * time = 3.4 * .75
*July 5, 2016*

**Prealgebra/probability**

tails, tails, heads does NOT work H H T H T H T H H Quarter, Penny could be H H H T T H T T that is four, 8 now for each so 32 so I agree
*July 3, 2016*

**physics**

add up the forces. That is one equation add up the torques (moments) about x = 0. That is the second equation
*July 3, 2016*

**physics**

C + W = 926 so 2 W = 1852 - 2 C then (1852 - 2 C) + .6 C = 736 1852 - 736 = 1.4 C etc
*July 3, 2016*

**physics**

190 down at left C up at x = .6 75*9.81 down at x = 1 W up at x = 2 forces up = forces down C + W = 190 + 75*9.81 = 926 Newtons moments about x = 0 sum to 0 -.6 C + 75*9.81*1 - 2 W = 0 or 2W +.6C = 736 Newton meters
*July 3, 2016*

**Physics**

lol, finally 33 * 50 = 12 x x = 33 * 50/12
*July 3, 2016*

**Physics**

so where is the fulcrum?
*July 3, 2016*

**LOL - not enough known**

I do not know either mass or the x of the right hand side
*July 3, 2016*

**Physics**

v = Vi + a t 0 = 30 + a (6) a = -5 m/s^2 ==================== v = Vi - 5 t 0 = 40 - 5 t t = 8 seconds
*July 3, 2016*

**physics**

work = force * distance so how far? assume v =0 at start F = m a 4 = 20 a a = (1/5) m/s^2 v = Vi + a t v = 0 + 3 a x = Xi + Vi t + (1/2) a t^2 x = 0 + 0 + (1/2)(9) x = 4.5 meters so W = F x = 4 * 4.5 = 18 Joules
*July 3, 2016*

**math**

2 (L+w) = 270 L + .75 L = 135 1.75 L = 135 L = 135/1.75 etc
*July 3, 2016*

**math**

a + 3 a = 80 so 4 a = 80 a = 20 etc
*July 3, 2016*

**Math**

b = (5/8) s so g = (3/8) s now g = (3/8) s + 6 and number of students = s + 6 b = 5/8 s = (3/8)s +6 so (2/8)s = 6 s = 24 that was original s s+6 = new total = 30
*July 3, 2016*

**better**

http://www.bbc.co.uk/schools/gcsebitesize/science/add_aqa_pre_2011/atomic/covalentrev4.shtml
*July 3, 2016*

**CHEMISTRY**

http://search.yahoo.com/yhs/search?p=dot+and+cross+diagram+H2O+bond&ei=UTF-8&hspart=mozilla&hsimp=yhs-001
*July 3, 2016*

**Physics**

find resultant and do the opposite. north 11 + 22 sin 30 east 22 cos 30 magnitude = sqrt(north^2 + east^2) tan angle north of east = north/east you want that magnitude but opposite direction, same angle south of west
*July 2, 2016*

**PHYSICS**

vol = 20 cm^3 ????? Your typing is very confusing then upward force = weight of water displaced (Archimedes) = 10 cm^3 * 1 gram/cm3 * g = 10 grams * g = .010 kg * 9.81 = .098 Newtons upward buoyancy but weight = volume * density * g = 20 * 2.5 * 9.81/1000 = 0.49 N difference...
*July 2, 2016*

**Math**

no if she made 65 out of 100 that will take less than if she made 650 out of 1000
*July 2, 2016*

**Physics**

(1/2) m v2^2 = 1.23 (1/2) m v1^2 so v2 = sqrt(1.23) v1 v2 = 1.11 v1 well, that is an 11% increase
*July 2, 2016*

**Mathematics**

25 letters allowed for first spot 25 for second spot so 625 letter combinations 9 digits 9*9*9*9 = 9^4 so 625*9^4 = 4,100,625
*July 2, 2016*

**physics**

or to do it the physics way: (4585 drops/ft^2)*(1 ft^2/15 tiles) = (4585 drops/ 15 tiles)
*July 2, 2016*

**physics**

4585/15
*July 2, 2016*

**patel**

must be bigger than 1 because 1^2 = 1 must be smaller than 2 because 2^2 = 4 so between 1 and 2 by the way sqrt 3 = 1.732050808 approximately
*July 2, 2016*

**Sciencr**

Yes, hot air holds more water. Fog happens if air saturated with all the moisture it can hold cools down. Similarly if saturated air comes in contact with a cool surface like a basement wall that air cools and the water condenses out. Interestingly by the way, hot water holds ...
*July 2, 2016*

**physics**

Are you sure the captain is a novice? Despite the fact that he will land downstream from his starting point, his fastest path across the water is to head straight across. Anyway I will pretend I am not a navigator and do what your book wants you to do. For example: He could be...
*July 2, 2016*

**gibberish**

please check what you wrote "Earth is 2R times far away from earth " makes no sense to me.
*July 2, 2016*

**physics**

force 1215 m what is that about? Anyway all that matters is depth p = rho g h = 1000 kg/m^3 * 9.81 * 3 = about 30,000 Pascals that is the pressure abouve the one atmosphere at the surface or "gage" pressure. That one atmosphere is about 100,000 Pascals so the total ...
*July 2, 2016*

**Math(Assignment Due**

http://davidmlane.com/hyperstat/z_table.html
*June 29, 2016*

**Math(Assignment Due**

Google David Lane normal distribution
*June 29, 2016*

**Math**

6*5*4*3= 30*12 = 360
*June 29, 2016*

**Math1**

165 * 1.04
*June 28, 2016*

**Calculus**

x^2 dy+2xydx - 2ydy +(1/xy)(xdy+ydx) = 0 [x^2-2y+1/y]dy + [2xy+1/x]dx = 0 dy/dx = -[2xy+1/x] / [x^2-2y+1/y]
*June 28, 2016*

**Math**

small left ---> large right 5467
*June 28, 2016*

**Probability and statistic**

http://davidmlane.com/hyperstat/z_table.html
*June 27, 2016*

**physics**

60,000 /3600 = 16.7 m/s 45,000 /3600 = 12.5 m/s v =Vi + a t 12.5 = 16.7 + 10 a a = -0.42 meters/second^2
*June 27, 2016*

**physics**

d = (1/2) a t^2
*June 27, 2016*

**Math**

in the slope/intercept form: y = m x + b m is the slope b is the y axis intercept where x = 0 here the slope is positive 0.5 so the line goes up to the right from the point (0,-2) (and of course down to the left :)
*June 27, 2016*

**Math**

y = 35 + 15 x
*June 27, 2016*

**maths**

(x-3)(3x+2)=0 alpha = 3 beta = -2/3 so (x-9)(x-4/9) = y x^2 -9x -4x/9 + 4 = y y = x^2 - (85/9) x + 4
*June 27, 2016*

**English**

One says "at". I suppose if you live in a tunnel, you eat "in" it :) However is you say: "What about dinner in my house?", You probably mean instead of in my yard or garage.
*June 26, 2016*

**GEOMETRY**

p(a)+ p (b) - p(a and b) 1,2,3,or 4 out of 6 = 4/6 tail = 1/2 = 3/6 4/6 + 3/6 - 2/6 = 5/6
*June 26, 2016*

**GEOMETRY**

prob of first one blue = 5/16 now we have 15 in the bag prob of white = 5/15 = 1/3 so 5/16 * 1/3 = 5/39
*June 26, 2016*

**GEOMETRY**

Hey, it is time you should be able to do these.
*June 26, 2016*

**GEOMETRY**

A and B could be 6 A and C - impossible B and C - impossible
*June 26, 2016*

**GEOMETRY**

the attempts are independent so (3/7)^3
*June 26, 2016*

**GEOMETRY**

2 out of 15 2/15
*June 26, 2016*

**GEOMETRY**

1/16
*June 26, 2016*

**math**

18,000 * 1.07^18
*June 26, 2016*

**GEOMETRY**

p even = 3/6 = 1/2 p A = 1/3 they are independent so 1/2 * 1/3 = 1/6
*June 26, 2016*

**Math**

cos T * sin T = 1/4 so 2 cos T * sin T = 1/2 so sin 2 T = 1/2 thus 2 T = 30 deg or pi/6 radians T = pi/12 radians or 15 deg now cos * sin must be + so T in quadrant 1 or quadrant 3 so actually T = pi/12 or T = 13pi/12 which is 195 deg pi/12 + 13 pi/12 + (2pi+pi/12) = (1/12 +13...
*June 26, 2016*

**Biology**

http://shenndesigns.weebly.com/my-physical-trait---curly-hair.html half of each assuming no one has only a little curly so 4:4
*June 26, 2016*

**maths**

a b a + b = 9 a = (1/2) b ============================== (1/2) b + b = 9 so (3/2) b = 9 so b = 18/3 which is 6 which means a = 3 and a b is 36
*June 26, 2016*

**math**

3 of anything + 3 of the same thing = 6 of them 6/30 = 1/5
*June 26, 2016*

**Science**

.05 * 90 = 4.5 mL
*June 26, 2016*

**math - incomplete problem statement**

(L+3)(w+3) = 84 + L w L w + 3 L + 3 w + 9 = 84 + L w 3 L + 3 w = 75 need another piece of information to solve Suspect you were given how much longer it was than wide
*June 25, 2016*

**Physics**

time t at 80 time t at 40 80 t + 40 t = 60 120 t = 60 t = (1/2) hour at each speed distance = 80(1/2) + 40(1/2) = 60km av speed = 60 km/1 hour
*June 25, 2016*

**physics**

north = 400 - 400 = 0 west = 300 d = sqrt (0^2 + 300^2) = 300 I have a hunch you have a typo.
*June 25, 2016*

**Physics**

capacitance is charge per unit voltage 60/40=1.5 Farads
*June 25, 2016*

**Maths Year 10**

x = k - 5 k x = k(k-5) = k^2 - 5k
*June 25, 2016*

**math**

54 = 15 + 3.25 x
*June 25, 2016*

**Science**

Will all that NaCl dissolve? I suspect not.
*June 25, 2016*

**math**

12 - 3 = 9 21 - 12 = 9 hmmm x - 21 = 9 maybe or x = 30 etc
*June 25, 2016*

**Mathematics**

a - (2/5)a = 24 3a/5 = 24 a/5 = 8 a = 40 yes
*June 25, 2016*

**CHEMISTRY**

NO-3 ? , SO2-4 ?, PO3 -4 Where did you get these strange charges for the ions? eg PO3 normally -3 ASSUMING your strange valences: In +3 NO -3 then to be neutral InNO In+3 * 4 = +12 SO2-4 * 3 = -12 so In4(SO2)3 similarly In4 (PO3)4 But I suspect you have the original statement ...
*June 24, 2016*

**trig**

north = -3*14+2*14*cos 60 east = 2*14*sin 60 d^2 = north^2 + east^2
*June 24, 2016*

**Math: PreCal**

yes, amplitude is five and period is 3 pi when x = 0: y = 5 cos (-pi/6) = 5 (.866) that is not a max or a min or and x intercept However there is always a reflection about the points where the argument of the cos function is zero because cos -z = cos z that is when (4/6)x = pi...
*June 24, 2016*

**physics**

some point (0,y) on y axis between y = -3 and y = +6 field up = k(-12)/(6-y)^2 field down = k(-5)/(y-3)^2 so 12(y-3)^2 = 5(6-y)^2
*June 22, 2016*

**physics**

find the linear velocity of the car from v = a t then angular velocity = v/R
*June 21, 2016*

**maths**

Ah, there, on a new computer that would not let me post link unless I typed my Jiska name in :)
*June 21, 2016*

**maths**

http://www.mathsisfun.com/numbers/dividing-by-zero.html
*June 21, 2016*

**English**

4-1 and 4-2 are correct although 4-2 is unlikely. 4. and 4-3 are incorrect.
*June 21, 2016*

**whoops, forgot what I did before**

I mean a = (F/m)e^-(bt/m)
*June 19, 2016*

**physic mechanic**

Friction force, unlike gravitational or electrostatic is not directed toward a source like a center of mass or a charge. Friction is therefore not a central force. Did you get your earlier one about a = F/m (1- e^(bt/m) ) alright?
*June 19, 2016*

**algebra**

each year value = 0.92 value year before v = Vi (0.92)^n v = 25,000 (0.92)^6
*June 19, 2016*

**Scient**

a mL of water is a gram 4.5 / x = .09 x = 50 grams water remains so 450 grams evaporated
*June 18, 2016*

**Physics**

7 m * 2 v = 14 m v (1/2)(7m)(2v)^2 = (1/2)(7)(4) mv^2 = 28 * (1/2)m v^2
*June 18, 2016*

**Physics (Normal force and static coefficient)**

F down slope = m g sin 42 = 2 * 9.8 * sin 42 = 13.1 Newtons down the slope so 13.1 = mu m g cos 42 or sin 42 = mu cos 42 mu = tan 42 mu = 0.900 At least 0.900 could be more
*June 18, 2016*

**Maths**

J = A - 15 J+10 = (1/2)(A+10) A - 15 + 10 = A/2 + 5 A/2 = 10 A = 20 J = 5 ========== check 2(5+10) = 20+10 30 = 30 sure enough
*June 18, 2016*

**Math**

In quad 2 sin is + cos is - of course we can look up the angle knowing the tangent and then find the sin etc but that is too easy. tan T = -5 = sin T/cos T cos T = sqrt (1 - sin^2 T) so -5 = sin T / sqrt(1-sin^2 T) 25 (1-sin^2 T ) = sin^2 T 25 = 26 sin^2 T sin^2 T = 25/26 sin ...
*June 17, 2016*

**Geo Quiz**

No way you could help the guy below you, Momen, who asked a far more difficult question luckily answered by Bob Pursley elsewhere.
*June 17, 2016*

**Geo Quiz**

All of your choices are nonsense the way you typed them without parentheses (x+3)^2 + (y-6)^2 = 25
*June 17, 2016*

**Geo Final**

surface area is 6 times area of one face = 6 (9) = 54
*June 17, 2016*

**social studies.**

You do not need help. You are doing just fine. For number four I might say the poor unemployed people of the country rather than the Republic itself.
*June 17, 2016*

**Calculus**

If you use right endpoints for the height of each rectangle, Bob has it I think and the answer would be 8. If you use trapezoids you get a more accurate answer, 9 , but they asked for the inaccurate answer.
*June 17, 2016*

**CALCULUS**

well, try this backwards assuming you answered correctly y = -4 cos [ ln(6x) ] dy/dx = -4 (-sin [ln(6x)]*6/6x = 4 sin [ln(6x)] / x I see nothing wrong with your answer.
*June 16, 2016*

**geometry**

(x+3) / (3x-1) = 1/2 2 x + 6 = 3 x - 1 x = 7 GR = 3(7) - 1 = 20
*June 16, 2016*

**Math**

subtract 3 t from both sides 2 c = 35 - 3 t divide both sides by 2 c = (35/2) - (3/2) t or c = 17.5 - 1.5 t
*June 14, 2016*

**Math**

well, they all amount to the same thing. add -2 x + 5 to both sides 4 x - 2 x = 9 + 5 2 x = 14 x = 7
*June 14, 2016*