Thursday
December 8, 2016

Posts by Damon

Total # Posts: 28,437

maths
http://www.gregthatcher.com/Mathematics/GaussJordan.aspx for the first one for example there are three rows and four columns 1 +1 +1 -3 1 -1 -2 13 1 +0 -4 25
October 24, 2016

physics
That is correct assuming that the ball is sliding, not rolling. If rolling there is a force back on the bottom of the ball to give it angular acceleration but I suspect you have not covered that. Let's just assume that is a net force of 3 N :) In other words the 3 N is the...
October 24, 2016

Algebra
150 miles /30 miles/gal = 5 gal
October 24, 2016

I need help, I'm stuck...what is the correct answe
There are 14 students 7 got less than 7.5 and 7 got more than 7.5 so 7.5 is median for mean 2(4)+2(5)+1(6)+2(7)+3(8)+4(10) =102 102/14 = 7.3
October 24, 2016

American Government
no taxes no army see: http://americanhistory.about.com/od/governmentandpolitics/f/articles_of_confederation_fails.htm
October 24, 2016

maths
divide 6 by 2 and square it, 9 x^2 - 6 x + 9 -9 (x-3)^2 - 3^2 3(x^2 + 20 x/3) (10/3)^2 = 100/9 3 [ x^2 + 20/3 x + (10/3)^2 - (10/3)^2 ] = 3 [ (x-10/3)^2 - (10/3)^2 ]
October 24, 2016

physics
gravity force down slope = m(acceleration down slope) m g sin 37.5 =(m v^2/r) cos 37.5 g tan 37.5 = v^2/r v^2 = r g tan 37.5 = 394*9.81 tan 37.5 v = 54.5 m/s
October 23, 2016

advanced math
16 + 169 = 185 = x^2 so x = square root of 185 = 185^0.5 = 13.6
October 23, 2016

Math
11/15 = .73 10/13 = .77 better
October 23, 2016

Math
legs = 4 p + 2 c = 52 p+c = 22 so p = 22-c 4(22-c) + 2 c = 52 88 - 2 c = 52 2 c = 36 c = 18 then p = 4
October 23, 2016

Geometry
tan 75 = 80/d d = 21.4 ft between buildings tan 62 = x/21.4 x = 40.3 = height abobe 80 so 120 ft
October 23, 2016

Physics
a = .09/480 = 9/48000 m/s^2 dv = a dt = (9/48,000) *7d/w*24h/d*3600s/h = 113 m/s we are assuming constant mass. Possibly fuel or even engine components were ejected. This is just the speed change due to the propulsion. Presumably there are also gravitational forces acting even...
October 23, 2016

Physics
energy stored in spring = (1/2) k x^2 = (1/2)(100)(.04) work done by friction = mu m g *d so 50*.04 = .2 * 1 *9.81* d solve for d
October 23, 2016

math
If they were 1 by 1 the diagonal would be 400 say n of them along each side diagonal is then n sqrt 2 =400 n = 400/sqrt 2 but n^2 is number of squares so answer = 400^2/2 =200*400 = 80,000 I suspect you mean the diagonal is 80 cm, not 800 by the way
October 23, 2016

Math
df = 4 dx so if you go from 3 to 2.9 that is dx = -.1 so df = -.4 and 5 - .4 = 4.6 sure enough
October 23, 2016

EASY MATH FOR 4TH GRADE
or 5 (3*1000 + 3*100 + 3*10 * 3*1) 15*1000 + 15*100 + 15 * 10 + 15*1 1*10,000+5*1000 + 1*1000+5*100 + 1*100+5*10 + 1*10 + 5 10,000 + 6,000 + 600 + 60 + 5 16,665 again I do not know how you are doing this in your class but suspect distributive property in some form.
October 23, 2016

EASY MATH FOR 4TH GRADE
5( 3000 + 300 + 30 + 3 ) 15,000 + 1,500 + 150 + 15 15,000 + 1,500 + 165 15,000 + 1,665 16,665
October 23, 2016

Calculus
x = 5 + 20 t y = -75 + 15 t z =distance =sqrt(25+5625) (I bet you meant 7.5 miles but oh well) dx/dt = 20 dy/dt = 15 at t = 0 x = 5 and y = -75 z^2 = x^2 + y^2 2 z dz = 2x dx + 2 y dy so dz = (x dx + y dy)/z and dz/dt = (x dx/dt + ydy/dt)/z = (5*20-75*15)/sqrt(25+56250
October 23, 2016

Physics need R
angular momentum of disk = (1/2) M R^2 omega final angular momentum of debris initial = m R^2 (v/R) = m v R so m v R = (1/2) M R^2 omega omega = 2 v (m/M) /R
October 23, 2016

Chemistry (atoms)
1 mole of water H2O has one mol of O so we have .0595 * 6.022*10^23 atoms
October 23, 2016

MATH
A = x y 50 x + 20 (2y) = 2000 or 5 x + 4 y = 200 5 x + 4 A/x = 200 5 x^2 - 200 x - 4A = 0 where is vertex of parabola? -b/2a = 200/10 =20 so x = 20 5(20) + 4 y = 200 4 y = 100 y = 25
October 23, 2016

Physics
s = speed 45.9 = u T where u = s cos 40 so T = 45.9 /(s cos 40) where T is time aloft rise time is half T or t = T/2 v = Vi - g t Vi = s sin 40 at top v = 0 s sin 40 = 9.81 t = 9.81[45.9/(2s cos 40] or 2 s^2 sin 40 cos 40 = 9.81*45.9 remember trig now
October 22, 2016

physics
m a = G m Mmoon /R^2 so 1.62 = G Mmoon/(1.738*10^6)^2
October 22, 2016

Physics
assume you mean cross product no what if they are perpendicular ?
October 22, 2016

physics
force = rate of change of momentum which is m a if the mass is constant 10 Newtons = change of momentum/0.10 second so change of momentum = 1 kg m/s by the way the change in speed would be 1/5 = .2 m/s
October 22, 2016

questions all the same
water density, rho, is about 1,000 kg/m^3 the mass of a column of water one square meter in cross section and h meters high is therefore: mass = rho * 1 * h = 1,000 h kilograms the weight of that mass is mg = 1,000 * 9.81 * h Newtons the pressure is that force over the one ...
October 22, 2016

hold it
Bob seems to be using vi both for vertical and horizontal speed I think in fact the original vertical speed is zero so h = Hi + 0 -4.9 t^2 1.8 = 21.9 - 4.9 t^2 t^2 = 4.1 t = 2.03 seconds to fall now the car has to go horizontal 58 meters in 2.03 seconds so I will call the ...
October 21, 2016

solve what for t?
Is it something like sin t = .5 or something?
October 20, 2016

physics need asap help
initial x momentum = m u initial y momentum = 2 m v final x momentum = 3 m (2) cos 37 final y momentum = 3 m (2) sin 37 so u = 6 cos 37 v = 3 sin 37
October 20, 2016

physics need help
integral of F(x) dx = a x^2/2 + b x^3/3 at 3 this is 9a/2 + 27b/3 at 1 it is a/2 + b/3 subtract 8a/2 - 26b/3 now put in a and b 40/2 + 52/3 etc
October 20, 2016

history
d is politically incorrect so you better pick c a is pretty funny as is b
October 20, 2016

Algebra 2
You can easily check this yourself. First 3 + 6 + 2 = 11 sure enough twice as many peanuts as almonds, yes total cost = 1.5*6 + 3*3 + 1.5*2 = 9 + 9 + 3 = 21 so yes, done
October 20, 2016

Math
takes time t for pump 1 the big one takes time 3 t for pump 2 so pump 1 does 1/t jobs/hr pump 2 does 1/3t jobs/hr (1/t + 1/3t) = 4/3t jobs/hr together (4/3t jobs/hr)9hr = 1 job 12 hours = t
October 20, 2016

PHYSICS- PROJECTILE MOTION
Your teacher is really trying to get to you with this separation of constant horizontal speed from increasing vertical speed. 89 * 3.10 centimeters if you really mean cm/s
October 20, 2016

Pre algbra
-20/30 - 9/30
October 20, 2016

PHYSICS- PROJECTILE MOTION
a) Trick question - it does not change. u = 1.90 b) v = -9.81 t so |v| = 9.81 (0.410) c) speed = sqrt (u^2+v^2) d) tan (angle down from horizontal) = |v|/u
October 20, 2016

physics
sqrt(9+4)
October 19, 2016

Calculus
line is y = -5 x + 3 so slope = -5 = slope of tangent f' = slope = 6 x - 7 where is that -5? 6 x - 7 = -5 6 x = 2 x = 1/3 so y = 3(1/9) -7(1/3) + 4
October 19, 2016

History
World War One?
October 18, 2016

Physics
Violet bends more than red the slower wavelength bends more so violet is slower
October 18, 2016

nobody knows
the other two sides must also have lengths.
October 18, 2016

Physics
f = sqrt (T/[m/L]) / 2L m = 8000 A L so 170 = sqrt (T/8000A)/4 680 = sqrt (T/8000A) also 1% = .01 = T/ (E A) so T/A = .01 E so 680 = sqrt (.01 E/8000) 462400 = .01 E/8000 E = 3.7 *10^11
October 18, 2016

physics
20 = (1/2)10 t^2 solve for t = 2 seconds d = 15 t =15*2 = 30 m
October 18, 2016

physics
The total momentum of the system can not change if there is no external force. Therefore 4
October 18, 2016

Math Question
parabola, not a line, because y is squared
October 17, 2016

Math
12 a + 8.5 s = 10,175 a+s = 950 so s = (950-a) 12 a + 8.5(950-a) = 10,175 12 a + 8075 - 8.5 a = 10,175 3.5 a = 2100 a = 600
October 17, 2016

Math
4x*1 = 4x
October 17, 2016

math
4x = 50 x = 12.5
October 17, 2016

Algebra
10x+4
October 17, 2016

History
How about basic language (Indo European) ?
October 17, 2016

Engineering
ABS density varies from 1.0 to 1.4 grams/cc you did not give any units except dollars .437 what? grams, pounds, kg , oz ?
October 17, 2016

Nobody knows
we do not know how much plastic each part takes
October 17, 2016

Math
21/4 + 41/16 is 84/16 + 41/16 your turn now
October 17, 2016

math
her speed = v current speed = 3 time up = 18/(v-3) time down = 18/(v+3) so 18[ 1/(v-3) + 1/(v+3) ] = 8 [ 1/(v-3) + 1/(v+3) ] = 4/9 [ v + 3 + v - 3 ] = (4/9)(v^2-9) 18 v = 4 v^2 - 36 2 v^2 - 9 v - 18 = 0 v = 6 for positive v root ----------------------------- check up speed = 3...
October 17, 2016

Physics
more like 12.7 did you take the square root? I think not :)
October 17, 2016

Physics
(1/2) v^2 = 9.81 (8.2) v^2 = 16.4*9.81
October 17, 2016

math
pi r^2 h = 25 so h = 25/(pi r^2) A = 2 pi r^2 + 2 pi r h but we know h(r) A = 2 pi r^2 + 2 pi r * 25/(pi r^2) A = 2 pi r^2 + 50/r r better be >0
October 17, 2016

math
he has made .4*20 = 8 of 20 he shoots total of 20 + x shots 8 + x = .5(20+x) 8 + x = 10 + .5 x .5 x = 2 x = 4 ==================== check he has now shot 24 and has made 8+4 = 12 sure enough 12/24 = .5
October 17, 2016

math
fewer dollars per oz or per pound is cheaper per pound of weight gained.
October 17, 2016

Math
1.5+1.2 = 2.7
October 17, 2016

Maths
How many do you think? Draw a picture.
October 17, 2016

maths
there are 2 pi radians in a circle C = 2 pi R so (2.5/2pi)(2 pi R) = 2.5 R = 2.5 * 8 = 20
October 17, 2016

algrebra
-6x = 2 x = -2/6 = -1/3
October 17, 2016

Math
1 1/2 = 3/2 (3/2)(42) = 3 (21) = 63
October 17, 2016

I don't either
I could say 7 + 31 + 6 = 44 low or 8 + 32 + 7 = 47 high but that would be kind of silly and I would be more likely to estimate using nearest whole numbers 8 + 31 + 7 = 46
October 17, 2016

math
L + w = 250 so L = 250-w L = 50 + w so 250 - w = 50 + w 2 w = 200 w = 100 L = 150
October 17, 2016

Math
LOL, ok dividing by 3 is the same as multiplying by 1/3 :)
October 17, 2016

Math
huh?
October 17, 2016

Math
(9/5)/3 = 3/5
October 17, 2016

Math
(-11/8)(14/5) = - (11/4)(7/5) = 77/20 = 3 17/20
October 17, 2016

Math
1.5 + 1.2
October 17, 2016

8th pre algebra
By the way that is algebra, not pre algebra :)
October 17, 2016

8th pre algebra
2(10) - 7 = ? sure enough 13 so you are right BUT actually you ADDED 7 to both sides
October 17, 2016

Trig
2sin 2Tcos2T/[1 + 2 cos^2 2T -1] = sin 2T cos 2T/ [cos 2T cos 2T] = sin 2T/cos 2T = tan 2T = 2 tan T/[1-tan^2T]
October 17, 2016

math
6.60/[12*710] or 9.18/[24*500] which is less dollars per mL ?
October 17, 2016

Physics (Mechanics)
m2 going up is + -m1 g + m2 g sin T= (m1+m2)a -2.5(9.8)+9.8m2 sin T=-(2.5+m2).108 -.8(9.8)+9.8m2sinT = (.8+m2)2.888 ---------------------------------- subtract to get rid of 9.8m2 sin T solve result for m2 go back and get m2 sinT and therefore sin T
October 17, 2016

math (Help)
if it has the square root of a variable in it (y^.5), it is not a straight line
October 17, 2016

sure do need steve
I can make no sense at all of your problem statement.
October 17, 2016

Math Functions
6000 + 1000 x
October 17, 2016

Math Limits
looks good to me
October 17, 2016

Math
It has y^2 in it. It is therefore a parabola, not a straight line e.
October 17, 2016

physics
v = Vi - 9.81 t at 1.7 s 19 = Vi - 9.81 (1.7) solve for Vi, launch speed at 5.4 s v = Vi - 9.81(5.4)
October 17, 2016

algebra
.55 V1 + .80 V2 = .6(50) and V1 + V2 = 50 so V2 = 50 - V1 .55 V1 + .8(50 -V1) = 30 etc
October 17, 2016

History
This is pretty important. What do you think?
October 17, 2016

physics
v = Vi - 9.81 t h = Hi + Vi t -4.9 t^2 ==================== 2.2 = 1.5 + 6.4 t - 4.9 t^2 solve quadratic for t then v = 6.4 - 9.81 t
October 17, 2016

Physics
72 km/hr = 72000/3600 = 20 m/s
October 17, 2016

Math
(6.4/2)100 = 320 %
October 17, 2016

math
you mean 2 - 3^2 ??? 2 - 9 = -7
October 17, 2016

6th grade math
another way to think about it: (3/4) pic / 1 sec = 6 pic/ x sec (3/4) x = 6 x = (4/3)6 x = 8 seconds
October 17, 2016

6th grade math
6 pictures[1 second/(3/4) picture] = 6 *4/3 = 8 seconds
October 17, 2016

Geometry
change in x = -15 change in y = -1 distance = sqrt(225+1) = sqrt(226)
October 17, 2016

typo
I mean .131/16 = .008 mols O
October 17, 2016

Science (Chemistry) Ratio of mole
If you had used mols O you would have had .13/.16 = .008 or two mols of O for every one of Mg so it would have been MgO2 anyway :)
October 17, 2016

math
L + w = 42 L + 3 = 4 w 42 - w + 3 = 4 w 5 w = 45 etc
October 16, 2016

Physics
normal force = m g cos 30 so friction force </= mu m g cos 30 can only say less than if object is not moving. component of weight down slope = m g sin 30 so if no other forces are acting m g sin 30 </= mu m g cos 30 or mu >/= tan 30
October 16, 2016

Math
maybe 1002001 ? That is a lot of km 2000 km / (35 + 48 + 45.5) = 15.56 km/L = 6.43 L/100 km
October 16, 2016

physics
http://www.physicsclassroom.com/class/sound/Lesson-5/Closed-End-Air-Columns
October 16, 2016

Physics Force and Friction question
max static friction force = .4*981 which is more than 350 so It stays in place. 350 N might be enough to keep it moving, but is not enough to start it.
October 16, 2016

need more info
Is it barely not moving, is it moving at constant velocity, is it accelerating?
October 16, 2016

Math( 7th grade advanced math so 8th grade math)
A = 3 x + 59 + 2*35 = 3x + 129
October 16, 2016

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