Thursday

November 26, 2015
Total # Posts: 22,924

**Physics what am I thinking**

Distance down = previous distance down + previous v * 1 + 4.9 * 1^2
*November 6, 2015*

**Physics typo**

Distance down = previous distance down + previous v * 4.9
*November 6, 2015*

**Physics**

yes at each second v = previous v + 9.81 Distance down = previous distance down + previous v + 4.9
*November 6, 2015*

**CHEMISTRY**

How many mols is 1.64 grams? K = 39 Cl = 35.5 O3 = 3*16 = 48 so a mol is 122.5 grams so we have 1.64/122.5 = .0134 mols KClO3 for every 2 mols KClO3 I get 3 mols O2 .0134 * 3/2 = .0201 mols O2 now at stp that is 22.4 * .0201 = .45 liters of O2 you do the PV=nRT to get volume ...
*November 6, 2015*

**Math Please check**

3 y = 4 x + 12 divide both sides by 3 so y = (4/3) x + 4
*November 5, 2015*

**chemistry**

5 mols SnO2 reqires 10 mols C but we only have 9 9 mols C require 4.5 mols SnO2 and yield 9 mols CO with half a mol SnO2 left over The 10 mols CO will kill you.
*November 5, 2015*

**please check my answers**

yes but we write it x^2 for x squared yes, constant slope is linear slope = change in y / change in x for example m = (16-7)/(9-3) = 9/6 = 3/2 y = (3/2) x + b if x = 3, y = 7 so 7 = (3/2)(3) + b 14/2 = 9/2 + b b = 5/2 so in the end y = (3/2) x + 5/2 if x = 7 y = (3/2)(7) + 5/2...
*November 5, 2015*

**physics**

time needed is 3/a
*November 5, 2015*

**physics ok, your way**

well to do the problem with your formulas v = Vi + a t 5 = 2 + a t so 3 = a t so t = 3/a and d = Vi t + .5 a t^2 5 = 2 t + .5 a t^2 5 = 2 (3/a) + .5 a (9/a^2) 5 = 6/a + 4.5/a 5 a = 10.5 a = 2.1 m/s^2 again
*November 5, 2015*

**physics**

distance from t1 to t2 = integral v dt = Vi (t2-t1) + .5a (t2-t1)^2 distance/time = average speed = Vi + .5 a (t2-t1) but speed at t2 is v2 = Vi + a (t2-t1) so a(t2-t1) = v2-vi so average speed = Vi + .5(V2-Vi) = .5 (Vi+V2) if you really wanted to know :)
*November 5, 2015*

**physics**

You can use average speed with constant acceleration because v = Vi + a t, straight line
*November 5, 2015*

**physics**

a = change in v/ change in time = (5-2)/time well how long did it take? average speed = 7/2 =3.5 time = 5/3.5 so a = 3 /(5/3.5) = 2.1 m/s^2
*November 5, 2015*

**chemistry**

Cu(NO3)2 --> CuO + NO2 + O2 unbaslanced now balance 2Cu(NO3)2 --> 2CuO + 4NO2 + O2 has 2 Cu has 4 N has 12 O good so 4 mols NO2 for each 2 mols Cu(NO3)2 so twice as many so 2
*November 5, 2015*

**chemistry**

mols HNO3/ mols NO2 = 2/3 so (2/3)5 = 10/3
*November 5, 2015*

**chemistry**

You need 3 mols of NO2 for each mol of H2O You can see that from your balanced equation. However You get TWO mols of nitric acid, not 3
*November 5, 2015*

**math/economics in calculus**

marginal cost = .03q^2-1.2q+13 where is that parabola a minimum If you know calculus take derivative and set to zero otherwise find the vertex of the parabila I will use calculus 0 = .06 q - 1.2 so min when q = 1.2/.06 = 20 then calculate q min = .03(20)^2 -1.2(20) + 13 the ...
*November 5, 2015*

**ALGEBRA**

49 - 36 = 13 64 - 49 = 15 so not a straight line so try them all y is not x^2 because 36 is not 1*1 y is not 36 x because that would be a straight line try y = (x+5)^2 1 ---> 36 5 ---> 100 sure enough so I agree
*November 5, 2015*

**Check my answers L.A**

Looks like home to me :)
*November 5, 2015*

**I need help again**

y = m x + b here distance = 4 (speed) + 22
*November 5, 2015*

**I need help again**

You are already 22 miles north then you travel 4 * 64 miles
*November 5, 2015*

**I need help again**

22 + distance traveled after entering pike = 22 + 4 * 64 = 22 + 256 = 278 miles This is just like the taxi problem really.
*November 5, 2015*

**HELLLLLLLOOOOO**

:)
*November 5, 2015*

**HELLLLLLLOOOOO**

Perhaps they want it in y = m x + b form then C = 2 m + 2.50
*November 5, 2015*

**HELLLLLLLOOOOO**

ashlyn does not have it right, sorry. Look at the problem and imagine how the meter works as you ride along the road :)
*November 5, 2015*

**HELLLLLLLOOOOO**

Oh my
*November 5, 2015*

**HELLLLLLLOOOOO**

You are welcome.
*November 5, 2015*

**HELLLLLLLOOOOO**

C = 2.50 + 2 m
*November 5, 2015*

**Math**

The z table is at that David Lane link
*November 5, 2015*

**Math**

When I say percent I men probability = percent/100
*November 5, 2015*

**Math**

LOL or subtract the percent between 2000 and 5000 from 100 :)
*November 5, 2015*

**Math**

http://davidmlane.com/hyperstat/z_table.html D -- add the percent < 2000 to the percent > 5000
*November 5, 2015*

**math**

ashlyn, not until you get linear relations right, sorry. By the way I graduated MIT in 1959.
*November 5, 2015*

**math**

Same thing, it has to be and remain the same on both sides If you add 5 on the left, you must add 5 on the right If you multiply left by two, you must multiply right by two
*November 5, 2015*

**math**

You need the same atoms coming out as went in. There are no nuclear reactions in a chemical reaction :) NOT H2 + O2 --> H2O, NO way 2 hydrogen atoms went in, 2 came out BUT 2 oxygen atoms went in, but ONLY ONE came out so we need 2 H2 + O2 --> 2 H2O 4 H atoms left, 4 H ...
*November 5, 2015*

**Physics**

.5 m v^2 = m g h so v = sqrt (2 g h) v = sqrt (2*9.81*3) = 7.67 m/s b) loss of energy = m g (3-2) = .5 * 9.81 * 1 = 4.9 Joules c) v = sqrt (2 g h) but h is 2 instead of 3 now
*November 5, 2015*

**Physics**

Vi = 55.1 sin 20 v = Vi - 9.81 t v = 0 at top so t = Vi/9.81 at top use that in h = Vi t - 4.9 t^2
*November 5, 2015*

**English**

Sept 11, 2001 is the date of the (9/11) attack on the World Trade Center in New York City. That is what he is talking about.
*November 5, 2015*

**math**

10/30 = 1/3 = 0.333333.........
*November 5, 2015*

**Physics**

heat in = 5 (T-20)C heat out = 1 (80 -T)C so 5 T - 100 = 80 - T 6 T - 180 T = 30
*November 5, 2015*

**Pre-Calculus**

2 y = 3 x + 9 is y = (3/2) x + 4.5 so slope of original is 3/2 slope of final is -2/3 y = (-2/3) x + b -2 = (-2/3)(-4) + b -2 - 8/3 = b b = -14/3 so 3 y = -2 x - 14 2 x + 3 y = -14
*November 5, 2015*

**Calculus 1**

p = 120 i / (i^2 + i + 4) dp/di = 0 at max or min 0 = [(i^2 + i + 4)120 - 120 i(2i+1)]/(i^2 + i + 4)2 look for zeros of numerator 0 = 120 i^2 +120 i + 480 -240 i^2 -120 i 0 = -120 i^2 +480 i^2 = 4 i = 2
*November 5, 2015*

**Physic**

F = m g sin 15 + .22 m g cos 15 power = force * speed = (m g sin 15 + .22 m g cos 15).2 in Joules/second or Watts
*November 5, 2015*

**physics**

a t = b t^2 + c t^3 + d a t is (force * distance / time) *time = m L/T^2 * L = m L^2/T^2 the other terms must have the same so b T^2 = m L^2/T^2 b has dimension m L^2/T^4 c T^3 = m L^2/T^2 c has dimensions m L^2/T^5 d is m L^2/T^2 by the way since a has dimensions of power ...
*November 5, 2015*

**physics**

v = Vi + a t in general so here v = 0 + a t for first part, this is max v then v = a t - 2 t b
*November 5, 2015*

**Math**

she means 3 * 2^(3x) I think
*November 4, 2015*

**math**

F = m a F = 5 * 15
*November 4, 2015*

**honors math**

now y = 3 x y = 3 x + anything is parallel y = (-1/3)x + anything is pependicular etc
*November 4, 2015*

**honors math**

Put them in the form y = m x + b for example with the first one: y = -5 x + 16 here m - -5 and b = 16 now parallel just has same slope m y = -5 x + 16,529 or any other b perpendicular means m' = -1m so here +1/5 y = (1/5) x + 16437 or whatever neight means m = 5735.787 so ...
*November 4, 2015*

**algebra**

n and n+1 n + n + 1 </= 9n - 5(n+1) 2 n + 1 </= 4 n - 5 2 n >/= 6 n >/= 3
*November 4, 2015*

**Physics**

F = m g + m a average speed in hand = (20 + 0)/2 = 10 m/s so time in hand = 1.47 m/10 m/s = .147 seconds a = change in speed / time in hand = 20/.147 so F = .18(9.8 + 20/.147)
*November 4, 2015*

**Physics**

29,000 / 2.2 = 13182 sqrt of that is 114.8
*November 4, 2015*

**Physics**

F = m Acc mu m g = m v^2/R v^2 = mu g R
*November 4, 2015*

**Calculus 1**

y = sin (pi x) graph it sin pi = 0 if you go around counterclockwise where is sin pi x= -1? where pi x = 3 pi/2 sin ( pi x ) = -1 so min when x = 3/2 we never get to x = 1/2 so max at pi/3 when sin pi x = sin 60 deg = sqrt 3/2
*November 4, 2015*

**Calc**

V = x^2 h = 4000 so h = 4000/x^2 A = x^2 + 4 x h A = x^2 + 4 x (4000/x^2) A = x^2 + 16,000/x dA/dx = 0 at max or min 0 = 2 x -16000/x^2 x^3 = 8000 x = 20 now do the rest
*November 4, 2015*

**Calc**

similar problem: http://www.jiskha.com/display.cgi?id=1446672601
*November 4, 2015*

**Math**

every time x changes by +3, y changes by -2 except for that +7 which I suspect is a typo slope of this straight line is therefore -2/3 so the function is of form y = (-2/3) x + b put in any old point to get b -1 = (-2/3)(-7) + b -1 = 14/3 + b b = -14/3 - 3/3 = -17/3 so y = (-2...
*November 4, 2015*

**Physics**

a = 10 m/s^2 v = a t = 10 t x = (1/2) a t^2 = 5 t^2 so if t = 4 x = 5 (16) = 80
*November 4, 2015*

**Porportions (Pre-Algerbra)**

I hope, practice that !
*November 4, 2015*

**Porportions (Pre-Algerbra)**

NO, you did them wrong ! A/B = C/x is the same as A x = B C or x = BC/A
*November 4, 2015*

**HEY - cross multiply**

2 x = 3*12 x = 3*6 x = 18 ========================= 22 H = 12 * 55 H = 30 ======================= 6 x = 11 * 84 x = 154
*November 4, 2015*

**Physics**

I just did this tonight ! http://www.jiskha.com/display.cgi?id=1446681195
*November 4, 2015*

**physics**

distance cat moves = 4 cos 29 * t = 3.5 m/s * t so x position of cat = 3.5 t x position of mouse = d + 2.2 t they hit when d = 1.3 t now vertical problem cat goes up at initial speed Vi = 4 sin 29 = 1.94 m/s at time t, the cat is back on the ground at time t/2 the cat has ...
*November 4, 2015*

**Math**

when x = 10, y = .01*1024 = 10.24 when x = 2 , y = .01* 4 = .04 change in y = 10.2 change in x = 8 10.2/8 = 1.275
*November 4, 2015*

**Physics**

average = 50/2 = 25 m/s v = a t = 10 t 25 = 10 t t = 2.5
*November 4, 2015*

**low math**

here it is using 9.14 http://www.jiskha.com/display.cgi?id=1446681878
*November 4, 2015*

**low math**

well, you fixed that 914 I used 9.14 but you can use my solution with 9.25
*November 4, 2015*

**low math**

I just did this
*November 4, 2015*

**Math**

Assume you mean 9.14 in wide there is one less space than board 15 boards 14 spaces so 15 * 9.14 + 14 * x = 144 137 + 4 x = 144 4 x = 7 x = 7/4 = 1.75 in
*November 4, 2015*

**Physics**

the attack truck was heavier :) If they were the same m1 * v + m2 *0 = (m1+m2) v final 2 m moves half as fast as 1 m but if m2 is smal then v final approaches v
*November 4, 2015*

**Physics**

Atangential = r alpha = .608 (65.3) = 39.7 m/s^2 Ac = omega^2 r = (19.7)^2 (.608) = 236 m/s^2 so mostly centripetal A = sqrt (236^2 + 39.7^2) =239.3 m/s^2 I get angle to radius vector = close to 180 because mostly centripetal tan angle above -x axis = 39.7/236 angle above -x ...
*November 4, 2015*

**Physics**

You are welcome.
*November 4, 2015*

**Physics**

When you drop a bomb always turn and climb The horizontal speed of the bomb is THE SAME AS the horizontal speed of the bomber It does not change with no air drag ! The bomb hits UNDER the plane so: How long to fall? 4780 = (1/2)(9.8) t^2 t = 31.2 seconds to fall how far ...
*November 4, 2015*

**AP-Physics**

The parabola :) d^2x/dt^2 = a constant acceleration dx/dt = v = initial speed Vi + a t (straight line) x = initial x + Vi t + (1/2) a t^2 quadratic, parabola
*November 4, 2015*

**Math**

x is the same y changes sign (6 , 2) DRAW A PICTURE !!!!!
*November 4, 2015*

**Physics radius typo**

How about we write + - as just - :) whoops typo = ten times further r2= 7.5x10^11 should be r2= 7.5x10^12
*November 4, 2015*

**Calculus**

I am not sure L'Hopital's rule is relevant here because the limit of the top derivstive is -oo and of the bottom is 1 but if you try it with numbers and your calculator you will indeed get -oo for example ln .0001 = -9.21 -9.21/.0001 = -92103
*November 4, 2015*

**Physics**

v = Vi + a t theta = theta zero + Vi t + (1/2) a t^2 when t = 0, v = 0 v = a t 5.9 = a(1.6) so a = 3.69 radians/s^2 now at 19 seconds: v = 0 + 3.69 (19) = 70.1 radians/s theta = 0 + 0 t + (.5)(3.69)(19)^2 = 666 radians NOW continues at 70.1 rad/s for 47 - 19 = 28 seconds so ...
*November 4, 2015*

**Calculus**

of course that is -(2/3) (cos x)^3/2 + c Your problem seems to be not replacing dx with a calculated du
*November 4, 2015*

**Calculus**

ok, let u = cos x then du = -sin x dx then you have ∫ (u)^(1/2)(-du) =-(2/3) u^(3/2) + c
*November 4, 2015*

**Math**

find it at x = 8 find it at x = 3 subtract f(8) - f(3) divide by 8-3, in other words divide by 5 and I can not do it because I do not understand your notation (still)
*November 4, 2015*

**Math**

3^(2x) = (3^2)^x = 9^x so 4 * 3^(2x) = 4 * 9^x agree B but watch notation carefully :)
*November 4, 2015*

**Math**

But what is the exponent ? Please use standard notation.
*November 4, 2015*

**I do not understand notation**

if you are doing exponents please write superscripts with an arrow up 4^3 = 4*4*4 = 64 2^(2*3) = 2^6
*November 4, 2015*

**Calculus**

I am not sure I follow you but when you change from t to u you must also change dt to du { like if u = t^3 + 1, then du = 3 t^2 dt and dt = du/3 t^2 which leaves you in a mess. You must also change the t limits, 2 to x to u limits if t = 2, u = 2^3+1 = 9 and if t = x then u = ...
*November 4, 2015*

**Algebra 1**

You are welcome
*November 4, 2015*

**Algebra 1**

You have given discrete points, not a function or continuous graph so the domain is discrete domain is the x values 3 , 4 , 9 range is the y values 2 , 6 , 8 , 9.5
*November 4, 2015*

**Algebra 1- Please help whenever you get the chance**

You are welcome.
*November 4, 2015*

**Algebra 1- Please help whenever you get the chance**

y went up ONE from x = 0 to x = 1 BUT y went up THREE from x = 1 to x = 2 therefore it is NOT linear, the slope changes then it went up five from 2 to 3 just to make it painful. You could do a parabola :)
*November 4, 2015*

**calculus**

base = 2 r height of rectangle = h area is A A = 2 r h + (1/2) pi r^2 perimeter = 2 r + 2 h + (1/2)(2 pi r)=20 (2 + pi)r + 2 h = 20 (1 + pi/2)r + h = 10 so h = 10 - 2.57 r A = 2 r (10-2.57r) + 1.57 r^2 A = 20 r - 5.14 r^2 + 1.57 r^2 or A = 20 r - 3.57 r^2 dA/dr = 0 for max = ...
*November 4, 2015*

**Calculus**

L = 3 w metal area = 2 L w = 6 w^2 wood area = 2 L h + 2 w h volume = 3 w^2 h = 45 so h =15/w^2 cost = 15*6 w^2 + 6*2 w h c = 90 w^2 + 12 w h or c = 90 w^2 + 12 w (15/w^2) c = 90 w^2 + 180/w at max or min dc/dw = 0 0 = 180 w - 180/w^2 1/w^2 = w w = 1^(1/3) = 1 then L = 3 then ...
*November 4, 2015*

**Physics**

dv/dt = a = -2 m/s^2 v = 30 - a t d = Vi t + .5 a t^2 so d = 30 t - 1 t^2 but t = 5 so d = 30*5 - 25 = 150 - 25 = 125
*November 4, 2015*

**Calculus**

well, just looking at the rightmost term where x = 2 we have sin (1/2) so I believe that you are correct and the teacher wrote sin( x ) instead of sin (1/x).
*November 4, 2015*

**Science**

a = change in v / change in time = (5.2 - 11) / 3.1 = -1.87 m/s^2
*November 4, 2015*

**Calculus**

v = pi r^2 h constraint is 90 = 2 pi r h + 2 pi r^2 45/pi = r h + r^2 or h = (45/pi - r^2 )/r so v = pi r^2 (45/pi - r^2)/r or v = 45 r - pi r^3 for max or min dv/dr = 0 dv/dr = 0 = 45 - 3 pi r^2 r^2 = 15/pi r = 2.185 now get v
*November 4, 2015*

**Calculus**

along building = w out from building = L total length = w + 2 L = p area = A = w L =250,000 so L = 250,000/w then the fencing perimeter p = w + 2 L = w + 500,000/w dp/dw = 0 for minimum dp/dw = 1 - 500,000/w^2 = 0 w = sqrt (500,000) = 707.1 L = 353.6 p = w + 2 L = 1414.2 cost...
*November 4, 2015*

**Math**

2 sqrt 3 * 2 sqrt (2*3) = 4 sqrt (9*2) = 12 sqrt 2 sqrt 2 is NOT rational
*November 4, 2015*

**Math 4grade**

You are welcome.
*November 4, 2015*

**Math 4grade**

23 is indeed closer to 25 than to 20 12 is closer to 10 than to 20 or even to 15 so 10 * 25 = 250 right the real answer is 276 so not bad 25 * 15 = 375 which is not nearly as good
*November 4, 2015*

**math**

-26 1/3 + x = + 10 ??? x = 10 + 26 1/3 x = 36 1/3 which I am sure you knew :)
*November 4, 2015*

**Social Studies**

I think I might use a word like more self confident rather than defiant but agree in general.
*November 4, 2015*