Tuesday

February 21, 2017
Total # Posts: 29,370

**Physics- Accleration of a Falling Penny**

google terminal velocity

*November 21, 2016*

**Physics**

Sorry for the long explanation. I am a naval architect and this subject is close to me :)

*November 21, 2016*

**Physics**

It is true if the body is floating. The force upward from the water is equal to the weight of the water displaced. If the body is floating, that water weight must be equal to the weight of the body and the body rises in the water until that is true. That is how ships float. If...

*November 21, 2016*

**Physics- Baseball thrown upwards, accleration**

THE ENTIRE TIME the acceleration is one g, about 9.8 m/s^2 downward. In other words yes, b

*November 21, 2016*

**Statistics**

http://davidmlane.com/hyperstat/z_table.html

*November 21, 2016*

**Physics-Tension Force**

infinite

*November 21, 2016*

**Physics**

.4 N up 9.8*.145 down m a = .4 - 9.8*.145 that is about .4 - 1.4 or -1 a = -1/.145 = about -7 a

*November 21, 2016*

**Science**

I replied .

*November 21, 2016*

**Math**

9 3/4 = 39/4 39/4 / 3/4 = 39/4 * 4/3 = 39/3 = 13

*November 21, 2016*

**TIP MATH!**

well Ms Sue used the fact that 15% is halfway between 10% and 20% I used a tenth plus half of a tenth. same difference :)

*November 21, 2016*

**TIP MATH!**

10% + 5% = 15% 2.3 + half of that 2.3 + 1.2 = 3.50 ps the accurate answer is 3.49

*November 21, 2016*

**Maths help asap please.**

n (n+1) + n+1 n^2 + n + n + 1 n^2 + 2n + 1 = (n+1)(n+1)

*November 21, 2016*

**Physics**

d = speed * time d = (100 km/60 min) * 5 min d = 25/3

*November 21, 2016*

**Science plsss help!**

4) I suspect is B 5) .5^6 = .0156 = 1.6 % agree second number 5, really that fast?

*November 21, 2016*

**Physics**

one of those two speeds is negative

*November 21, 2016*

**math**

sin ? = 1/1.25 tan ? = sin ?/cos ? = 1/v

*November 20, 2016*

**physics**

sqrt (100 + 16) = sqrt 116 = srt (4*29) = 2 sqrt(29) tan angle above x axis = 4/10 |a| = (1/.5) *2 sqrt 29 = 4 sqrt 29 at same tan^-1(.4)

*November 20, 2016*

**calculus antiderivation**

Vi = 60 mi/h * 5280 ft/mi /3600 s/h Vf = 45 * 5280/3600 Vf = Vi - 11 t solve for t =========================== 0 = Vi - 11 T T = Vi/11 d = Vi T - 5.5 T^2

*November 20, 2016*

**Math**

1.5/6 = x/16 x = 16 * 1.5 / 6

*November 20, 2016*

**Maths trigonometry**

tan 30 = 150/x

*November 20, 2016*

**factor of 2**

for part b .5 m g (d+x) = .5 k (x)^2 + .5 m v^2 we know d from part a m v^2 = m g d + m g x - k x^2 m v dv/dx = m g - k x dv/dx = 0 at max v k x = m g

*November 19, 2016*

**Physics**

You are welcome.

*November 19, 2016*

**Physics**

Not that easy m g (d+.23) sin 30 = .5 k (.23)^2 sin 30 = .5 so m g (d+.23)= k (.23)^2 3.2 (9.8)(d+.23) = 443 * .23^2 =========================== for part b m g (d+x) = k (x)^2 + .5 m v^2 we know d from part a .5 m v^2 = m g d + m g x - k x^2 m v dv/dx = m g - 2 k x dv/dx = 0 ...

*November 19, 2016*

**Physics**

Slides (d + .23) total m g (d+.23) sin 30 = .5 k (.23)^2

*November 19, 2016*

**math - business**

The y intercept is where x = 0 so -12,000 is correct The x axis intercepts are when y, the profit, = 0 that is when x = 2 and z = 15 correct the 15 is from 6000 - 400 x = 0 x = 60/4 x = 15

*November 19, 2016*

**Math Help**

probability of no boys = .5^5 so probability of one or more than 1 = 1 - .5^5 = .969

*November 19, 2016*

**calc**

so displacement is zero and distance is 5.33 + 15.75 + 10.42 = 31.5 check my arithmetic !!!!

*November 19, 2016*

**calc REPAIR of displacement**

v = t^3 - 10 t^2 + 27 t - 18 integral = t^4/4-10t^3/3 +27t^2/2 -18t at 7 integral = -7.58 at 1 integral = -7.58 so displacement = 0

*November 19, 2016*

**calc**

I used this to do the numbers: http://www.mathportal.org/calculators/calculus/integral-calculator.php t = 1 to t = 3 int = +5.33 t = 3 to t = 6 int = -15.75 t = 6 to t = 7 int = +10.42 so distance = -21.5 this also says my answer for part 1 should have been 5.33 -15.75+10.42...

*November 19, 2016*

**calc**

(t-1)(t-3)(t-6) = 0 so 1 to 3 then 3 to 6 then 6 to 7

*November 19, 2016*

**calc**

integrate to find x(1) and x(7) x(7)-x(1) is the displacement vector to find the distance scalar we must know when the particle is moving forward and when back and integrate over those intervals adding absolute values v = t^3 - 10 t^2 + 27 t - 18 integral = t^4/4-10t^3/3 +27t^...

*November 19, 2016*

**Calc**

integral of (500-3t) = 500 t - 1.5 t^2 at t = 13, integral = 500(13)-1.5(169) = 6500 - 253.5 = 6246.5 liters

*November 19, 2016*

**Math**

integer

*November 18, 2016*

**Math**

Are you sure you mean sqrt(-9) ??? That is an imaginary number. Maybe you mean sqrt (25-9) = sqrt (16) which is 4 which is a whole number and an integer

*November 18, 2016*

**Math**

5 + sqrt -9 5 + 3 sqt(-1) 5 + 3 i complex

*November 18, 2016*

**math**

m < 13 n > 13 p < 5 I think you mean at most 35 people 20 + a <= 35 a <= 15 so no more than 15

*November 18, 2016*

**watch units!**

watch out, km/hour given

*November 18, 2016*

**Calc**

a = (V2-V1)/(t2-t1) V2 = 90,000/3600 = 25 m/s V1 = 25,000/3600 = 6.94 t2-t1 = 13 so a = 1.39 m/s^2 ====================== d = V1 t + (1/2)a t^2 = 6.94 *13 + .695*169 = 208 m

*November 18, 2016*

**Science**

sounds right to me

*November 18, 2016*

**Math**

using same web site for normal dist A = .1 M = 72 sd = 9 .1 area is anything below 60.46 If I try bottom .3, anything below a C, I get A = .3 ---> below 67.28, that is the boundary for the HIGHEST D

*November 18, 2016*

**Math**

http://davidmlane.com/hyperstat/z_table.html area = .4 mean = 72 SD = 9 .4 are between 71.5 and 72.5 so 71.5

*November 18, 2016*

**physics**

total drop = 2.2+ .55 = 2.75 m drop in gravity Potential energy = = 6.95 * 9.81 * 2.75 = increase in spring Pe = (1/2)k x^2 = .5 *k * .55^2 so k = (6.95*9.81*2.75)/(.5*.55*.55)

*November 18, 2016*

**math algebra**

cold 1/8 tub/min hot 1/12 tub/min drain -1/7 tub/min so sum 1/8 +1/12 - 1/7 tub/min = 3/24 + 2/24 - 1/7 = 5/24 - 1/7 = 35/168 - 24/168 = 11/168 tubs/min = 168/11 min/tub = 15.3 min

*November 18, 2016*

**Math**

false say 1 by 1 1*1 = 1 cm^2 but 1.1 * 1.1 = 1.21 cm^2 .21 is more than .1 :)

*November 18, 2016*

**physics**

Ke = (1/2)m v^2 = Pe = (1/2)k x^2 (1/2)m (2v)^2 = (1/2)k (nx)^2 v^2 multiplied by 4 so x^2 multiplied by 4 so 2 times original x

*November 18, 2016*

**Math**

mean win = (1+2+3+0+0+0) = 6/6 = $1 so lose .25 per toss so lose $25 for 100 games

*November 18, 2016*

**PRE-CALCULUS**

a) 150,000 * 1.054^20 = 320,440.07 check do the others the same way as I showed you in the previous problem below

*November 18, 2016*

**PRE-CALCULUS**

r = .12/n where n = times per year a = 5000 * (1+r)^8n eg annual: 5000 * 1.12^8 semi where n = 2 5000 * 1.06^16 quarterly where n = 4 5000 *1.03^32 etc continuous a = 5000 e^.12 t = 5000 e^.96 = 13058.48

*November 18, 2016*

**Math**

3*18 = 54 m^2

*November 17, 2016*

**Math**

b/g = 7/9 g-12 = b so (g-12)/g = 7/9 9(g-12) = 7g 2 g = 108 g = 54 b = 42 sum = 96

*November 17, 2016*

**Science**

on the other hand if he carried it 500 m UP, then 100 * 500 = 50,000 Joules The problem does not say direction so who knows?

*November 17, 2016*

**MATH HELP!!**

Starlight Tree Farm sells Douglas firs and Noble firs. One December they sold 139 more Douglas firs than Noble firs. The total number of trees sold was 377. Which equation could be used to solve for n, the number of Noble fir trees sold

*November 17, 2016*

**MATH HELP!!**

You are welome

*November 17, 2016*

**MATH HELP!!**

25 6/25 - 20/25 = -14/25

*November 17, 2016*

**math**

100 times the fraction

*November 17, 2016*

**US History**

I guess maybe because Fort Neccessity is near Pittsburgh?

*November 17, 2016*

**Calculus**

delta x = .1 x range ____ y at right 1.0 to 1.1 ____ 2/1.1 = 1.82 times .1 = .182 1.1 to 1.2 ____ 2/1.2 = 1.67 times .1 = .167 1.2 to 1.3 etc in the end add them up .182 + .167 etc

*November 17, 2016*

**US History**

I do not think slaves were in Rhode Island before about 1700 so I agree with you. Pilgrims landed in Plymouth MA in 1620 and settlement of RI was thus later than that. I have my doubts about timing in SC as well.

*November 17, 2016*

**physics typo?**

Vi = 47 m/s d = 50 =============== v = Vi + a t 0 = 47 + a t a t = -47 or a = -47/t =============== d = Vi t + .5 a t^2 50 = 47 t + .5 a t^2 50 = 47 t +.5(-47/t)t^2 50 = 47 t - .5*47 t 50 = .5*47 t t = 100/47 then a = -47/(100/47)= -22 m/s^2 > twice gravity I think maybe ...

*November 17, 2016*

**Math**

13 = .65 x x = 13/.65 = 20

*November 17, 2016*

**Math**

(1/3)/5 = 1/15 but 5/(1/3) = 15

*November 17, 2016*

**US History**

The Spanish certainly DID find gold. They became the most powerful country in Europe for a while due to their riches from the New World. So I agree with you.

*November 17, 2016*

**Math algebra**

I have a hunch you mean f(x)= (x-2)/(x^2-81) which is (x-2)/ [ (x-9)(x+9) ] it is zero if the numerator is zero so when x = 2 it is undefined when the denominator is zero x = 9 or x = -9

*November 17, 2016*

**Math algebra**

AVA + .2*10^9 = 2 * AVE T + .6*10^9 = AVA AVA + AVE + T = 6.5*10^9 ============================ do them all in billions well T = AVA - .6 AVE = .5 AVA + .2 so AVA + .5 AVA + .2 + AVA - .6 = 6.5 2.5 AVA = 6.9 take it from there

*November 17, 2016*

**Math algebra**

(20+2x)(30+2x) = 936 600 + 100 x + 4 x^2 = 936 4 x^2 + 100 x - 336 = 0 x^2 + 25 x - 84 = 0 (x - 3 )(x + 28) = 0 x = 3 feet

*November 17, 2016*

**ANOTHER TRIANGLE MATH PROB!**

Get it?

*November 17, 2016*

**ANOTHER TRIANGLE MATH PROB!**

I said 12, and 12 is an option

*November 17, 2016*

**ANOTHER TRIANGLE MATH PROB!**

Now maybe you need to do this a more official way to really get it 21/24 = 10.5/x we want to get the 24 and the x out of the bottom so multiply both sides by 24 x 24 x (21/24) = 24 x (10.5/x) 21 x = 24 * 10.5 x = 24 * (10.5/21) x = 24 * (.5) x = 12

*November 17, 2016*

**ANOTHER TRIANGLE MATH PROB!**

21/24 = 10.5/x well 10.5 is half of 21 and we all know 12 is half of 24 so 10.5/12

*November 17, 2016*

**Physics === Not hard**

(1/2) k x^2 = (1/2) m v^2 k (.07)^2 = .0055 (11.4)^2

*November 17, 2016*

**physics**

Ke = (1/2) m v^2 = .5*.00335 * 255^2 in Joules = mass * heat of fusion of water = 3.35 * 333 J/gram

*November 17, 2016*

**Math (equation of tangent line)**

That is the second strange tangent line problem today. The first one was horizontal :)

*November 17, 2016*

**re: Differential Calculus**

Just copy your function into there: x^2cos^2y - siny = 0 look at the solution close to (0,0)

*November 17, 2016*

**re: Differential Calculus**

I mean parallel to x axis and y = pi for part 2, normal is up the y axis see http://www.wolframalpha.com/widgets/view.jsp?id=91851988c40ebbe236f5561e167c9ab8

*November 17, 2016*

**Math**

You are welcome.

*November 17, 2016*

**Math**

sqrt 15 = 3.873 3.873 * 10 = 38.73 which is about 39 so yes

*November 17, 2016*

**TRIANGLE HELP!!!! (MATH!)**

3/4 = 6/8 = 9/12 = 12/16 = 15/20

*November 17, 2016*

**math**

74 + 12*52 = 74 +624 = 698

*November 17, 2016*

**Tod**

Cool !

*November 17, 2016*

**math**

7/12 blue (12-7)/12 = 5/12 red

*November 16, 2016*

**Math**

(1/3) n = 5 n = 3*5 = 15 nights

*November 16, 2016*

**Math**

1.06 * 20.00 = 21.20

*November 16, 2016*

**Arithmetic**

3 for .20 is 12 for .80 so profit of .80-.70 = .10 dollars/dozen so .60 = 60 cents for 6 dozen

*November 16, 2016*

**Physics**

eff = Q/W = T2/(T1-T2) T2 = 26 + 273 T1-T2 = 33-26 = 7 eff = 299/7 = 42.7

*November 16, 2016*

**Physics**

gain in potential = m g h = 65 * 9.81 * 1100 Joules eff = ..25 so .25 energy = 65* 9.81 * 1100 so energy expended = 4*65*9.81*1100 Joules 4184 Joules = 1000 calories so in Calories (4/4.184)65*9.81*1100 power = energy expended/ time in watts = 4*65*9.81*1100/(37.5*60)

*November 16, 2016*

**Math**

1 2 3 4 5 6 first die 1 1 1 1 1 1 second die 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 6 6 total of 36 possibles the number one shows up 11 times 36 -11 = 25 times no ones 11/36 -25/36 = - 14/36 = -7/18

*November 16, 2016*

**not linear**

3495 *.8^t .8^5 = .328 or about $1150 which is not nothing but is also not much

*November 16, 2016*

**Algebra**

maybe: same as the probability that one of the numbers you choose is zero probability that first one is zero = 1/6 probability that second one is zero also is 1/6 so sum is 2/6 = 1/3

*November 16, 2016*

**CHEMISTRY**

try Gooling: ETHYLENE GLYCOL or antifreeze :) suspect it is Ethane-1,2-diol

*November 16, 2016*

**Calculus**

do the integral 4(x^2+1) dx/x^2and divide by the span which is 3-1 = 2 4 x^2 dx/x^2 + 4 dx/x^2 is 4 x - 4/x = 4 (x-1/x) at 3 = 4(3-1/3) = 32/3 at 1 = 0 so 32/3 divide by 2 16/3

*November 16, 2016*

**American government**

Well, if you just want my opinion as an uninvolved friend of the student, yes.

*November 16, 2016*

**American government**

I hope not. Read: http://www.google.com/search?q=amicus+curiae&ie=utf-8&oe=utf-8

*November 16, 2016*

**american government**

http://www.jiskha.com/display.cgi?id=1479316937#1479316937.1479317141

*November 16, 2016*

**Dynamics**

Vi = 80,000 m/3600 s a = -3.24 v = Vi + a t 0 = 80/3.6 - 3.24 t d = Vi t + (1/2) a t^2 = (80/3.6) t - 1.62 t^2

*November 16, 2016*

**Calculus**

(4/3)(x+3)^(1/3) but 0^(1/3) = 0 so right, zero

*November 16, 2016*

**Math**

x = xi - 5 y = yi + 7

*November 16, 2016*

**math**

b-s = 15 3 b = 8 s so b = 8s/3 8s/3 - 3s/3 = 15 5 s/3 = 15 s/3 = 3 s = 9 b = 9+15 = 24

*November 16, 2016*

**maths**

200 + 200 + 300 + 300 :)

*November 16, 2016*

**Science**

.01 * 6*10^23 * electrons per ion Do you really mean total electrons or valence electrons? If the latter it is two.

*November 16, 2016*

**math**

1.25^n = 2 n log 1.25 = log 2 n = log 2/ log 1.25

*November 16, 2016*