Thursday

January 19, 2017
Total # Posts: 28,803

**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*

**physics**

oh my, still in feet? in this case g = about 32 ft/s^2 v = 58 - 32 t at top t = 0 t at top = 58/32 seconds total time in air by the way = 2 t = 58/16 seconds now the problem: h = Vi t - .5 * 32 t^2 H = 58 (58/32) - .5 * 58^2/32 (A.) H = 58^2/64 ft (B.) 2 t = 58/16 sec when h...

*October 16, 2016*

**Math( 7th grade advanced math so 8th grade math)**

ah 4 8 16 32 64

*October 16, 2016*

**Math( 7th grade advanced math so 8th grade math)**

4*2^n n = 4 quarters of and hour 2^4 = 16 so 4*16 = 64

*October 16, 2016*

**Science/Math**

If it did not float then 5 mL

*October 16, 2016*

**Math**

well, I am inclined to multiply first equation by 4 and second by 3 -56 x + 60 y = 12 +63 x - 60 y + 30 ------------------- add 7 x = 42 so x = 42/7 then -14(42/7) + 15 y = 3 -84 + 15 y = 3 15 y = 87 y = 87/15 ========================= try that in the second one to check 21(42...

*October 16, 2016*

**Social Studies**

Just for fun: http://www.nationalgeographic.com/travel/top-10/ancient-highways/ http://www.bbc.com/news/magazine-33291373

*October 16, 2016*

**Social Studies**

Did historical Japan have good roads? Did the Incas? How were each governed? How did they communicate with other nations?

*October 16, 2016*

**Math**

g = number of girls 5g/7 = number of boys g - 5g/7 = 120 2g/7 = 120 g/7 = 60 g = 420 then boys = (5/7)420 = 300 and 420 + 300 = 720 total

*October 16, 2016*

**chemistry**

Do you mean in catalytic converter? Maybe read "types" section in here: http://en.wikipedia.org/wiki/Catalytic_converter

*October 16, 2016*

**Math**

using common denominator of 18: 10/18 , 7/18 and 9/18 Now you rearrange them.

*October 16, 2016*

**physics**

2.9*9.81 Newtons

*October 15, 2016*

**chemistry**

A certain wavelength or frequency corresponds to a certain photon energy which is a certain change of energy of the electron shell around the atom. In other words the frequency tells you how an electron orbit changed.

*October 15, 2016*

**calculus**

dh/dt = -9.8 t + 10 when t = 1 dh/dt = 10-9.8 = 0.2

*October 15, 2016*

**math**

x y change in y/change in x which is slope -2 9 ****** -5 -1 4 ****** -5 0 -1 ****** -5 1 -6 ****** -5 2 -11 hmmm, constant slope = -5 y = -5 x + b 9 = -5 (-2) + b 9 = 10 + b b = -1 so y = -5 x -1 answer check at last point -11 = -5(2) -1 -11 = -10 - 1 yes, good

*October 15, 2016*

**Cousino**

speed upstream = 8 - u speed downstream = 8 + u time upstream = 5/(8-u) time downstream =5/(8+u) so 5(8-u) + 5/(8+u) = (4/3) hr 5(8+u) + 5(8-u) = (4/3)(64-u^2) 15(8+u) + 15(8-u) = 256(64-u^2) etc, solve quadratic

*October 15, 2016*

**be careful with parentherses**

do you mean 1/(2a) or (1/2)a 1) f(-2) = 4 a^2 +2a + 3b = 4 a^2-b+8 f(-3) = 9 a^2 +3a + 3b = 7a^2-b+14 so 2 a + 3 b = - b + 8 2 a + 4 b = 8 a + 2 b = 4 or a = 4 - 2 b and then 2 a^2 + 3 a + 4 b = 14 2(16 - 16 b +4b^2) + 3(4-2b) +4b=14 32 -32b +8b^2+12 -6b +4b = 14 30 + 8b^2 -...

*October 15, 2016*

**physics**

v = velocity up = 30 sin 30 - 9.81 t u = velocity horizontal = 30 cos t if t = 1 v = 15 - 9.81 u = 30(.866) speed = sqrt (u^2+v^2) tan angle up = v/u

*October 15, 2016*

**math**

as y--->0 cos y = 1 - y^2/2 + ........ numerator: 2 - 1 +(1/2)(9)x^2 -1 +(1/2)(16)x^2 0 + (25/2)x^2 oh my now divide by x 25 x/2 goes to 0 as x goes to 0

*October 15, 2016*

**math**

by the way tangent of small angle approaches sine of that small angle :) theta + theta^2/2 .......

*October 15, 2016*

**math**

Hey, I did the other one, try series approach on this one too.

*October 15, 2016*

**math**

m = math only s = science only b = both = 10 31 = m + b = m + 10 so m = 21 s+b = 36 - m s + 10 = 36 - 21 s + 10 = 15 so = Answer all science students s = 5 only science ======================== check 21 + 10 = 31, yes all math students 5 + 10 = 15 , yes all science students 21...

*October 15, 2016*

**Pre-calculus**

This is what it is about: http://www.youtube.com/watch?v=zw0waJCEc-w sin 45 = (1/2)sqrt 2

*October 15, 2016*

**Pre-calculus**

well, 7 = 6 + 1 so it is really sin (6 pi/12 + pi/12) sin(a+b) = sin a cos b + cos a sin b (just like your other problem) sin 6 pi/12 = sin 90 = 1 cos pi/12 = cos 15 deg cos 90 = 0 so cos 15 degrees

*October 15, 2016*

**Math**

y = k/x^3 new y = k/(x/2)^3 = 8 k/x^3 8 times as big

*October 15, 2016*

**english**

I have made 100 ship models in my life. I had made 100 ship models when they told me to stop and start doing physics problems.

*October 13, 2016*

**Maths**

9 km/(3/2)hr = 18/3 = 6 km/hr

*October 13, 2016*

**Math- Please check my answer!**

6/8 = 60/80 8/10 = 64/80

*October 13, 2016*

**Math**

2 driveways/day * 5 d/w = 10 driveways/week 10 driveways/week * 50 work weeks/yr = 500 driveways/year Now as Myah said, what is the question?

*October 13, 2016*

**physics**

heat of fusion * 150 g + 150 * heat capacity* (T-0) = 300 * heat capacity*(50-T)

*October 13, 2016*

**Physics**

normal forces 5 kg block: 5(9.81) 10 kg block 5*9.81 and 15*9.81 forces 5 kg block .2 * 5 * 9.81 right T left no acceleration so T = .2 * 5 * 9.81 = 9.81 N (answer to part C by the way) 10 kg block T left .1 * 15 * 9.81 left 45 N right so 45 - 9.81 - .1*15*9.81 = 10 a the end

*October 13, 2016*

**physics**

h = 1 = (1/2)(9.81)t^2 (a)solve that for t, the fall time u t = 1.5 (b)so u = 1.5/t v = g t = 9.81 t speed = sqrt (u^2+v^2) tan angle below hor = |v|/u

*October 13, 2016*

**8th Grade Math**

y = k x -12.5 = 50 k -25 = 100 k k = -1/4 y = -x/4 y = - (47/4) / 4 = - 47/16

*October 12, 2016*

**math**

(5)(3/13) - 2(10/13) = -5/13 You better stay away from this game. There are 13 cards in each suit of which 3, the jack, queen and king are winners. The other 10, ace through 10, are losers

*October 12, 2016*