Monday

April 21, 2014

April 21, 2014

Total # Posts: 16,198

**physics**

2000 meters - 40 meters = 1960 meter fall vertical fall problem first 1960 = 4.9 t^2 t = 20 second fall so it has to go 200 meters horizontal in 20 seconds u = 200/20 = 10 m/s

**Payback periods**

cost per year = 32,000 + 55,000 = 87,000 revenue per year = 100,000 profit/year = 13,000 so after ten years you have made 130,000 but you have depreciated the property to zero 550,000 -130,000 = 420,000 invested and not paid back From now on you make 100,000-32,000 = 68,000 pe...

**physics**

potential energy when? at the top?

**Math**

465 y = 155 x - 35 y = (155/465) x - 35/465 y = (1/3) x - 7/93 when x = 0 y = -7/93 no matter what you do starting with -7/93 going up with a slope of 1/3 it will be hard to get an integer y

**physic**

That is not one.

**SS --- one question pls help asap!!!!!**

I do not think it is a very well worded question.

**SS --- one question pls help asap!!!!!**

People moved from farms I think looking for jobs, not so much for Harvard.

**math linear equation**

1 +3 +2 +3 2 -1 -3 -8 5 +2 +1 +9 go to http://www.gregthatcher.com/Mathematics/GaussJordan.aspx 2, -3, 5

**Math**

(y -1) = +/- 3 if y-1 = + 3 then y = 4 if y-1 = -3 then y = -2

**Math**

twice :)

**Math**

as written it is not a function but an equation that has two solutions 2 x - 5 = -4 x^2 4 x^2 + 2 x - 5 = 0 that is the zeros of the parabola y = 4 x^2 + 2 x - 5 which are x = [ -2 +/- sqrt (4 + 80) ]/8 = - .25 +/- 1.15 = -1.39 and + .90

**optimisation**

A = (1/2) pi r^2 + 2 r w perimeter = 2 r + 2 w + 2 pi r = 850 = 2 r(1+pi) + 2 w 425 = r(4.14) + 2 w 213 = 2.07 r + w w = (213 - 2.07 r) A = .5 pi r^2 + 2r(213 - 2.07r) A = 1.57 r^2 + 425 r - 4.14 r^2 2.57 r^2 -425 r = -A r^2 - 165 r = -A/2.57 r^2 - 165 r + 6806 = -A/2.57 + 680...

**Algebra**

10^3 = 1,000

**physics**

h = Hi + Vi t - 4.9 t^2 0 = Hi + 20 (8) - 4.9(64) 0 = Hi + 160 - 314 Hi = 154 meters

**Physics**

distance = 1000 meters average speed = 90/2 = 45 meters/second so it took 1000/45 = 22.2 seconds to stop acceleration = change in velocity/change in time a = (0 - 90)/22.2 = - 4.05 m/s^2

**PHYSICS**

17(12) + (1/2)(1.37)(144)

**physics**

average velocity = (Position at start - position at finish) which is a vector divided by time In x direction runner goes: 38 meters so velocity in x direction is 38/13 = 2.92 m/s in x direction

**Algebra**

if x = 0 then 3(0)^2 - 5(0) = 0 if x = -1 then 3(-1)^2-5(-1) =3*1+5 = 8 if x = 2 then 3(4)-5(2) = 12-10 = 2

**physics**

average velocity = (Position at start - position at finish) which is a vector divided by time In x direction runner goes: 38 meters so velocity in x direction is 38/13 = 2.92 m/s in x direction

**math**

.06 2/3 = (6 + 2/3)/100 = (20/3)/100 = 20/300 = 1/15

**Classical mechanics**

Hmmm, looks like an 8.01 problem

**physics**

You are welcome :)

**physics**

99 = 4.9 t^2 t = 4.495 s 10 * 4.495 = 44.95m = 45.0 m to nearest tenth

**physics**

no, velocity is a vector. I has both magnitude (speed) and direction (NE or SW or whatever). These two vectors are in opposite directions.

**physics**

so?

**physics**

Vi = 4 h = Hi + Vi t - 4.9 t^2 0 = 0 + 4 t -4.9 t^2 t = 4/4.9 = .816 seconds before it is back down .816 * . 7 = .571 meters Your cannonball is remarkably slow, typo?

**physics**

driver goes 30 t cop goes .5 a t^2 = 1.2 t^2 so 30 t = 1.2 t^2 t = 30/1.2 seconds or of course they are also together at t = 0 :)

**Calculus 3**

anyway that would put the center at x = -1 y = 1/2 z = -1/4

**typo?**

x^2+4??????y^2 ?????+2z^2+2x-4y+z = 20 if so x^2 + 2 x = -(+4y^2+2z^2-4y+z) + 20 x^2 + 2 x + 1 = -(+4y^2+2z^2-4y+z) + 21 (x+1)^2 = -(+4y^2+2z^2-4y+z) + 21 4 y^2 - 4 y = -(x+1)^2 -2 z^2 -z + 21 y^2 - y =(1/4)[-(x+1)^2 -2 z^2 -z + 21] y^2-y+1/4=(1/4)[-(x+1)^2 -2 z^2 -z + 22] 4(y...

**math**

L + 2 W = 120 so L = 120 - 2 W A = L W A = (120-2W)W = 120 W - 2 W^2 so 2 W^2 -120 W = - A W^2 - 60 W = -A/2 W^2 - 60 W + 900 = -A/2 + 900 (W-30)^2 = -(1/2)(A-1800) vertax of parabola at (30,1800) so W = 30 L = 120 - 60 = 60 and A = 1800 m^2

**Physics**

They both experience the same gravitational force, m g their acceleration is therefore F/m = g Period, no other force, no other acceleration.

**Physics**

222 * 530 = original momentum 4 v + 218 * 410 = final momentum original momentum = final momentum

**CHEMISTRY**

85.2 - 48 = 37.2 mg of X 4 X atoms for every 10 O atoms 10 * 16 = 160 4 * X = 4x 4x/160 = 37.2/48 4 X = 160 *37.2/48 X = 31 check 31 * 4 = 124 16 *10 =160 124/160 = .775 and 37.2/48 = .775 good

**Math**

X y = (5 - p) y = (5-p)/X

**Physics**

You are welcome :)

**Physics**

momentum before = momentum after .018*222 = .018*72 + 3.9 * v

**Physics**

weight component down ramp = m g sin T so m g sin T = m a 4.7 = 9.81 sin T sin T = .479 T = 28.6 degrees d = (1/2) a t^2 6.4 = 2.35 t^2 solve for t LOL - the mass cancels, no difference

**Math**

1/2 = 5/10 2/5 = 4/10

**math**

1 dog 2 cats 2/15 of a parrot 2/45 of a snake I suppose you mean to say 6 snakes for 7 turtles in which case 2/45 *7/6 = 7/135 turtles so cats/turtles = 2 /(7/135) = 270/7

**Math**

sin^-1 .7245 = 46.4 deg in quadrant 1 or in quadrant 2 180 - 46.4 = 133.6 deg

**Math**

sin^-1 .7245 = 46.4 deg in quadrant 1 or in quadrant 2 180 - 46.4 = 133.6 deg

**Physics**

67 km/hr (1000 m/km) (1 hr/3600 s) = 18.6 m/s 18.6 m/s * 1.26 s = 23.5 meters

**Math**

sin^-1 .7245 = 46.4 deg in quadrant 1 or in quadrant 2 180 - 46.4 = 133.6 deg

**Phyiscs**

weight component down slope = 98.1 sin 25 = 41.5 N weight component normal to ramp = 98.1 cos 25 = 88.9 N max static friction = 88.9*.5= 44.5 N initial weight of bucket = 2*9.81 = 19.6 N force up ramp = 19.6 N force down ramp = 41.5 N Net force before friction down ramp = 41.5...

**Algebra 2**

v = Vi - g t h = hi + Vi t - 4.9 t^2 after 3 seconds h = 40 + 10 (3) - 4.9*9 = 25.9 meters above ground on the way down 0 = 40 + 10 t - 4.9 t^2 4.9 t^2 - 10 t - 40 = 0 t = [ 10 +/- sqrt(100 +784) ] / 9.8 take big t choice (on the way down) t = 4.05 seconds

**Math 1 question**

You are welcome :)

**Math 1 question**

(base/2)* height 11 * 7 = 77

**Math**

yes y^50 * y^10 = y^60

**math**

(5/20) * 100 = 25 %

**math percents**

33 = .12 x x = 33/.12 = 3300/12 well 3300/10 = 330 3300/11 = 300 so I would do what you did and say 300-30 = 270 which is not a bad estimate, off by 5. (5/275) *100 = 1.8 percent Of course you could be more accurate with long division.

**Math**

1.((3)/(2b^4))^3 ((27)/(8b^12)) Yes 2.((t^4)/(10y^4))^-4 (10000y^16)/(t^16) Yes 3. Does the rule y = -3(4^x) represent an exponential function? an exponential function is a constant raised to the power of the argument. So Yes

**trig**

You are welcome :)

**trig**

d = r theta = (d/2)theta theta = 2 radians

**Math**

A boat costs $92,000 and depreciates in value by 15% per year. How much will the boat be worth after 10 years? 18,112.45 78,200 18,941.98 69,000 18,112.45 <--------- agree A $6000 principal earns 8% interest compounded semi annually after 35 years. What is the balance? A. 2...

**math***CHECK ANSWER*****

.2 * 20 = 4 so yes

**physics**

find v of the book at ground (1/2) m v^2 = m g h so v = sqrt (2 g h) = sqrt (9.81 *150/2) = 27.1 m/s average book speed down = 27.1/2 = 13.6 m/s time book fell = 150/13.6 = 11 seconds so the balloon is at 150 + 1.2 * 11 = 163 meters

**Math**

so pick -4

**Science**

Newton #3 equal (in magnitude) and opposite (in direction)

**goverment**

administration ?

**U.S History - Need help to check my answer**

You have it right.

**math**

12 = (2/7)f so f = (7/2)12 = 42 42 - x = 4(12 -x) 42 - x = 48 - 4 x 3 x = 6 x = 2 years ago ----------------- check that was when Amanda = 10 and father = 40 good, that works :)

**Pre calc**

sin 2 x = 2 sin x cos x = 1/4 = .25 then 2 x = arc sin (.25) which is 14.5 degrees so x = 7.25 degrees

**Math**

(4/5) tank = 20 so tank = 20(5/4) tank = 25 L

**Math**

(2/3)cup/bowl * n bowls = 8 cups n = 8(3/2) = 12

**Physics**

120 - 82 = 38 newtons to LEFT F = m a 38 = 75 a a = 0.507 m/s^2 to the left

**physics**

F = 100 cos 30 = 86.6 N = 100 (sqrt 3)/2 a = F/m = 86.6/40 = 2.17 m/s^2 =(100/80)sqrt 3 = (5/4) sqrt 3 m/s^2 so five square roots of three all over four meters per second squared

**Physics**

delta x = .05 *10^-9 m delta x * delta p = (1/2) hbar = .5*10^-34 delta p = (.5*10^-34)/.05*10^-9) = 10 * 10^-25 kg m/s mass of electron * delta v = 10*-24 delta v = (10*10^-25)/(9*10^-31) delta v = 1.1 * 10^6 m/s

**physics**

Hey, are these sonar transducers in water or speakers in air or what? (I am a naval architect - sonar) Spatial pulse length: Length of a pulse from front to back = length of each cycle times the number of cycles in the pulse. Shorter pulse length improves resolution. .1925*5 =...

**physics**

T = 1/f = (1/8)*10^-6 = .125*10^-6 s = .126 microseconds .6/.125 = 4.8 about 5

**physics**

Huh, speed of sound not normally a function of frequency

**physics**

This is why I asked what medium. You need speed of sound which is five times faster in water than in air. Period = 1/f wavelength = speed of sound * period

**physics**

Oh, ultrasound here is tutorial with this material: https://www.cis.rit.edu/research/ultrasound/ultrasoundintro/ultraintro.html

**Physics**

fall from 18 m, what is speed (1/2) m v^2 = m g h vlaunch = sqrt(2 gh) that is your launch speed for second part optimum launch angle is 45 degrees. so do horizontal and vertical problems u = horizontal velocity = vlaunch/sqrt 2 Vi = initial speed up = vlaunch/sqrt2 distance =...

**Physics**

yes

**Physics**

LOL f = 1/T

**physics**

yes 2 *10^-7 = .2 * 10^-6

**physics**

T = 1/f

**physics**

T = 2 pi sqrt(L/g) 5 = 2 pi sqrt(L/9.81) L/9.81 = .63326 L = 6.21 meters

**science**

F = m a 50 = 100 a a = 0.5 m/s^2

**Physics**

orbit radius squared

**Physics**

31 days (24 hr/day)(3600 s/hr) = 2.68*10^6 seconds circumference of orbit = 2 pi r = 23.9*10^8 so v, speed = 23.9*10^8/(2.68*10^6 = 8.91*10^2 m/s Ac = v^2/r = 79.4 * 10^4 / 3.8*10^8 = 20.9 *10^-4 m/s^2 F = m a G Me m/r^2 = m Ac note m moon cancels 6.67*10^-11 Me/14.4*10^16 =20...

**Math**

forget the q for the time being, add it in at the end 6 p^2 -17 p + 12 (2 p - 3)(3 p - 4) now put the q back (2 p - 3 q)(3 p - 4 q)

**math**

pmt = Principal { r/[1 - (1+r)^-n ] } r = interest per period = .075/12 = .00625 n = 12 * 5 = 60 periods pmt = 10^5 {.00625/[1-(1.00625)^-60]} = 10^5 (.0200379) = $2,003.79

**Basic Linear Algebra**

The function is zero when it crosses the x axis so 0 = 3 x - 12 12 = 3 x x = 4 ---------------------------- When it crosses the y axis x = 0 so f(0) = 5(0) + 1 f(0) = 1

**Angle of elevation**

tan 60 = h/12

**Physics**

That is an ellipse. I do not know why you are interested in its length along the x axis but ok. x^2/p^2 = (1 - y^2/q^2) p^2 = x^2/(1 - y^2/q^2) p = +/- x / (1-y^2/q^2)^.5 note if y = 0 then x = +/- p =the semi axis of the ellipse

**Basic Algebra**

2 y = 4 x = 10 y = 2 x - 5 so m = slope = 2

**proportional relationship**

proportional means y = m x linear means y = m x + b because of the 4000 feet, this is of form y = -200 x + 4000 which is linear but not proportional

**Math**

doing it your way 72 - (2*12*(1/2)) is 72 - 12 = 60 ft^3 again

**Math**

sand height is 2.5 feet (3' - half foot) 12 * 2 * 2.5 = 12 * 5 = 60 ft^3

**Math Multiplying Fractions**

50*25 * 3 = 3750 m^3 3750 m^3 (1000 liters/m^3) = 3,750,000 liters

**physics**

mass does not matter m v^2/R = m g so v^2/R = g v^2 = 9.81* 41.5 v = 20.2 m/s

**Science**

You are welcome

**Science**

flower, tree and firewood are all biotic. Others are not. Your other answers look reasonable.

**math**

6*2 = 12

**Math**

3*5*3 = 45 3*5*5 = 75 that is 30 more cubic feet

**math**

W * (6/5) = 11/12 (5/6)(W) (6/5) = (11/12)(5/6) W = 55/72

**History!**

10. Daniel Webster !

**History!**

8. European oppression upon the newly independent nations of the Western Hemisphere will be treated as oppression upon the United States itself. <<<<<<<<<

**History!**

4. What made the United States a transcontinental power in 1819? (1 point) Adams-Onís Treaty <<<<<<<<<<<<<<<<<<<<<< Louisiana Purchase Monroe Doctrine*** War of 1812

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