# Posts by Damon

Total # Posts: 30,065

**Science**

eg: http://www.ucmp.berkeley.edu/mammal/marsupial/marsupial.html

**Science**

google kangaroo, marsupial :)

**help me plz**

I wish I knew what rt{t} meant but anyway we will need to do r of 9 and delta r for delta t at t = 9 r = t i + t^1.5 j + e^.25 t k dr/dt= i + 1.5 t^.5 j + .5 e^.25 t so dr (your delta r) = dt i + 1.5 t^.5 dt + .25 e^.25 t dt j Then r(9)= 9 i + 27 j+ 9.49 k dr = dt i + 4.5 dt j...

**calculus**

The DOMAIN is all real t HOWEVER the RANGE is only from -1 to +1 in i and -4 to + 4 in j and all real numbers in k

**science**

Senpai - buying books instead of borrowing from the library uses up trees (as well as a lot of other stuff like fuel).

**science**

Which do you think Jaden? Think of the effect of each answer on trash heaps and energy supplies and forests.

**Science**

initial momentum = 1 kg * 7 m/s - 2 kg * 7/6 m/s = = 14/3 kg m/s final momentum is the same 14/3 = 1 * V1 + 2 * V2 so V1 = 14/3 - 2 V2 initial Ke = (1/2)(1)(49) + (1/2)(2)(49/36) final Ke = .75*initial Ke = (1/2)(1)V1^2 + (1/2)(2)V2^2

**PHYSICS PLEASE HELP ME**

force of gravity down slope = m g sin 30 = .5 m g force of friction up slope = FF use FF to get angular acceleration FF r = I alpha so alpha = FF r/I = FF r/(2/5 mr^2) alpha = 5FF/2mr FF = 2 m r alpha/5 a = r alpha so alpha = a/r and F = m a so m a = .5 m g - FF m a = .5 m g...

**math**

I do not know what your triangle looks like area outside triangle = circle area pi r^2 - triangle area

**maths**

volume of sphere = (4/3)pi r^3 pi R^2 h = (4/3) pi r^2 h = (4/3) r^2/R^2

**maths**

just like your other problem, your turn

**Physics- Equilibrium**

If I had to pick one it would be c. Constant velocity means no acceleration which means no net force.

**Physocs- Components of Resultant Vectors**

A = 5 i - 3 j B = 5 i + 4 j --------------- C = 10i + 1 j

**Physics- Accleration of a Falling Penny**

google terminal velocity

**Physics**

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

**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...

**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

**Statistics**

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

**Physics-Tension Force**

infinite

**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

**Science**

I replied .

**Math**

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

**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 :)

**TIP MATH!**

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

**Maths help asap please.**

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

**Physics**

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

**Science plsss help!**

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

**Physics**

one of those two speeds is negative

**math**

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

**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)

**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

**Math**

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

**Maths trigonometry**

tan 30 = 150/x

**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

**Physics**

You are welcome.

**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 ...

**Physics**

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

**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

**Math Help**

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

**calc**

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

**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

**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...

**calc**

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

**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^...

**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

**Math**

integer

**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

**Math**

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

**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

**watch units!**

watch out, km/hour given

**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

**Science**

sounds right to me

**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

**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

**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)

**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

**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 :)

**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

**Math**

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

**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

**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

**Math**

3*18 = 54 m^2

**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

**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?

**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

**MATH HELP!!**

You are welome

**MATH HELP!!**

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

**math**

100 times the fraction

**US History**

I guess maybe because Fort Neccessity is near Pittsburgh?

**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

**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.

**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 ...

**Math**

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

**Math**

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

**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.

**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

**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

**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

**ANOTHER TRIANGLE MATH PROB!**

Get it?

**ANOTHER TRIANGLE MATH PROB!**

I said 12, and 12 is an option

**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

**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

**Physics === Not hard**

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

**physics**

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

**Math (equation of tangent line)**

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

**re: Differential Calculus**

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

**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

**Math**

You are welcome.

**Math**

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

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

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

**math**

74 + 12*52 = 74 +624 = 698

**Tod**

Cool !

**math**

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

**Math**

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

**Math**

1.06 * 20.00 = 21.20

**Arithmetic**

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

**Physics**

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

**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)

**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

**not linear**

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