Tuesday

October 21, 2014

October 21, 2014

Total # Posts: 18,996

**SCIENCE - PLEASE HELP PLESE**

2) Find the weight of a 12.25 kg dog. Round your answer to the correct number of significant figures. Use weight=massxfree-fall acceleration. g is different in different places on earth. We need it to four significant figures because your mass is to four sig figs. I will call ...
*September 28, 2014*

**SCIENCE - PLEASE HELP PLESE**

1) Round 578.683 m, 47.3333 kg, and 789.5 cm to four significant figures. 0,1,2,3,4 round down 5,6,7,8,9 round up 578.6 83 8 is greater than 4 so this becomes 578.7 meters 47.33 33 3 is less than 4 so this becomes 47.33 kilograms 789.5 cm This already has four significant ...
*September 28, 2014*

**trigo**

h = L (1-cos T) geometry exact cos 2A = 1 - 2 sin^2 A identity so cos T = 1 - 2 sin^2 (T/2) h = L [ 1 - (1 -2 sin^2 (T/2) ] = L [2 sin^2 (T/2) ] = 20 sin^2 (T/2)
*September 28, 2014*

**physics**

2.4*84
*September 28, 2014*

**physics**

84*.24
*September 28, 2014*

**geometry**

height = h = 280/40 V = (1/3)(40)(h) the volume of any pointy thing with straight sides = (1/3) base area * height
*September 28, 2014*

**math**

in the ten based number system: To multiply by ten, add a zero To divide by ten, move decimal point one space left 200 / 10 = 20.0 = 20
*September 27, 2014*

**physcis**

.926 = (1/2)(9.8) t^2 solve for t u = 18.3/t
*September 27, 2014*

**physics**

r = 33*10^6 + 6.37*10^6 2 pi r = circumference of orbit v = 2 pi r/(24 h * 3600 s/h) Ac = v^2/r
*September 27, 2014*

**physics**

1.1 = Vi t - 4.9 t^2 t = 4.4/u but u = Vi because tan 45 = 1 1.1 = u t - 4.9 t^2 1.1 = u t - 4.9 (4.4^2)/u^2 1.1 u^2 = u^2 (4.4) - 94.9 3.3 u^2 = 94.9 u = Vi = 5.36 m/s sqrt(u^2+Vi^2) = 7.58 m/s
*September 27, 2014*

**physics**

45 F = 30*(45-15)
*September 27, 2014*

**physics**

200*10^3 = .2*10^6 m high R earth = 6.38*10^6 so R = 6.58 * 10^6 meters G = 6.67384 × 10-11 m3 kg-1 s-2 earth mass = Me = 5.97*10^24 kg m v^2/R = G Me m /R^2 v^2 = G Me/R = 6.67 * 5.97 /6.58 * 10^(-11+24-6) = 6.05 * 10^7 = 60.5 * 10^6 so v = 7.78*10^3 = 7,780 m/s (PART B...
*September 27, 2014*

**physics**

a = change in velocity / change in time = -16.7 / t t = distance/ average speed = .67/8.35 = .0802 second so a = -16.7 / .0802 = -208 agree F = m a = 42 * -208 = -8736 Newtons AGREE
*September 27, 2014*

**Math**

Try the rest now.
*September 27, 2014*

**Math**

10 balls at start 1 prob black, white, red = 3/10 * 4/9 * 5/8 2 prob black, red, white = 3/10 * 5/9 * 4/8 same as above 3 prob white, black, red = 4/10 * 3/9 * 5/8 same again 4 prob white, red , black same 5 prob red , white, black same 6 prob red, black, white same so 6 * 3/...
*September 27, 2014*

**Engineering science**

fresh water is about 1 kg/Liter so m g h/t = 9000 kg * 9.81 * 70/3600 seconds = 1717 Watts done = 1717 Joules/second * 3600 seconds/hr = 6,180,300 Joules/hour = 1717Joules/second*60 s/min = 103,020 Joules/min
*September 27, 2014*

**science**

3000*1 = F = 4000 * x x = .75 m/s^2
*September 27, 2014*

**chemistry**

. 4 mol/liter = .0004 mol/mL 30 * .0004 = 0.012 mol NaOH .012 mol NaOH in 100 mL is .12 mol/liter
*September 27, 2014*

**physics**

Gravitational force = G mplanet m/d^2 G = 6.67384 × 10-11 m3 kg-1 s-2 so FB = 6.67384 × 10-11 m3 kg-1 s-2 MB*6930/(3.01*10^6)^2
*September 27, 2014*

**physics**

FB = G MB 6930/(9*10^12) FA = G MA 6930/(9*10^12) MA = (9*10^12/6930 G) FA MB = (9*10^12/6930 G) FB ---------------------------- MA - MB = (9*10^12/6930 G)(FA-FB)
*September 27, 2014*

**chemistry**

100 (4.78/6.67)
*September 27, 2014*

**math**

multiply first equation by 6 6 x + 30 y = 36 6 x - 15 y = 18 --------------- subtract 45 y = 18 y = 18/45 = 6/15 x = 6 - 5 y x = 6 - 2 x = 4
*September 27, 2014*

**chemistry**

check, yes they add to 100 well, let's say we have 100 grams of this stuff Then we have 62.04 grams of C 62.04 / 12 = 5.17 mols of C 10.41 mols of H 27.55/16 = 1.72 mols of O 10.41/5.17 = 2.01 so 2 H for every C 10.41/1.72 = 6.05 so 6 H for every O 3C 6H 1O or C3H6O which ...
*September 27, 2014*

**Physics**

2 pi radians is a revolution so 8 pi radians is four revolutions
*September 27, 2014*

**Algebra 2**

one out of 50 bears caught is tagged so 50 * 50
*September 27, 2014*

**math**

distance flown = 16/cos 60 = 32 km 32 km/(1/60)hr = 60 * 32 = 1920 km/hr
*September 27, 2014*

**chemistry**

mol of NO2 mass = 14+32 = 46 grams/mol mol of N = 14 100 * 14/46 = 30.4%
*September 27, 2014*

**Algebra 2**

There must be more to this problem than just (y-1)/(x+3) = -3/4 That is the equation of a straight line 4 y - 4 = -3 x - 9 4 y = -3 x - 5 y = -(3/4)x - 5/4
*September 27, 2014*

**math**

a60 = a1 + (59)(7) a60 = -15 + 413 = 398 S60 = 60 (-15 + 398) / 2 =11490
*September 27, 2014*

**Math one question?**

350 +225 ----- =575
*September 27, 2014*

**physics**

power stage v = Vi + a t v = 0 + 25 * 3.77 v = 94.25 m/s when fuel runs out h = 0 + 0 t + (1/2)(25)(3.77)^2 h = 177.7 meters high when fuel runs out Coasting stage, Hi = 177.7 meters and Vi = 94.25 m/s then at top v = 0 0 = 94.25 - 9.81 t t = 9.61 seconds coasting up h = Hi + ...
*September 26, 2014*

**Pre-Calc**

(f+g)(x) = x + x + 2 - 2 = 2 x do the others the same way
*September 26, 2014*

**Science-HELP?**

at least it works until the sea rises a little :(
*September 26, 2014*

**Science-HELP?**

sure, that works
*September 26, 2014*

**physics**

I answered that. http://www.jiskha.com/display.cgi?id=1411686019
*September 25, 2014*

**Physics**

Horizontal F = m v^2/r Vertical Fmax = m g + mv^2/r m g + m v^2/r = 1.16 m v^2/r g = .16 v^2/r .16 v^2 = 9.8(.7) solve
*September 25, 2014*

**Match**

162 + 284 is something like 140 + 300 which is 440 you don't need 98 to get to 500 from there
*September 25, 2014*

**Math**

http://davidmlane.com/hyperstat/z_table.html
*September 25, 2014*

**Algebra 1**

.91 = sum of first 6/6 so sum of first 6 =5.46 sum of first seven then is 5.46 + x so (5.46 + x)/7 >/= .92 5.46 + x >/= 6.44 so x >/= .98
*September 25, 2014*

**Algebra 1**

you can not just say less than 90 because you must include 90 therefore less than OR EQUAL TO 90
*September 25, 2014*

**Algebra 1**

Because It could be EXACTLY 80 or EXACTLY 90
*September 25, 2014*

**Algebra 1**

top will get 90 bottom will get 80 so what do you think?
*September 25, 2014*

**math...**

looks good to me.
*September 25, 2014*

**physics**

acceleration = change in velocity / change in time = (35 - 65) / 4.2
*September 25, 2014*

**Physics**

a = -9.81/4 = -2.45 m/s^2 0 = 6 - 2.45 t t = 2.45 seconds d = Vi t + (1/2) a t^2 d = 6 (2.45) - 1.23 (2.45^2) d = 7.31 meters
*September 25, 2014*

**Physics**

m v1^2/r = (9) m v2^2/r v2^2/v1^2 = 1/9 v2/v1 = 1/3
*September 25, 2014*

**math**

2. y + 2y + 3z combine like terms y + 2 y = 3 y so 3 y + 3 z B. 3y + 3z =================== Hey, you got the first one right. This is really no different 3. 6r + r - 5r (6+1-5)r = 2r A. 2r ========================= 4. 5x + 2(x + 6) is 5 x + 2 x + 12 or 7 x + 12 C. 7x + 12...
*September 25, 2014*

**Physics**

v1^2/r1 = v2^2/r2 v1^2/v2^2 = r1/r2 v1/v2 = sqrt (r1/r2)
*September 25, 2014*

**Physics**

weight = k r^3 drag = c r^2 v^2 at terminal speed, drag/weight = 1 drag/weight = const v^2/r so V1^2/R1 = V2^2/R2 V2^2/V1^2 = R2/R1 V2/V1 = sqrt (R2/R1)
*September 25, 2014*

**Algebra**

[(-3 x + 2 )(-2) -14 ]/6 [(6 x - 4 ) -14 ]/6 [6 x -18 ]/6 x - 3 write it down add three and you get x back :)
*September 25, 2014*

**Calculus**

f(x+h) = (x+h)^2 + x + h = x^2 + 2 h x + h^2 + x + h f(x) = x^2 + x slope = [f(x+h) - f(x) ]/h = [ 2 h x + h^2 + h ]/h = 2 x + h + 1 now at the point x = -1, h --->0 and slope = 2 x + 1 which is -2 + 1 = -1 so form of tangent is y = -1 x + b now what is y at x = -1 y = (-1...
*September 25, 2014*

**Physics**

assuming the current is perpendicular to the swimmer heading, it has nothing to do with the problem. It just means she will land somewhere downstream of the starting point. distance = speed * time = 0.4 * 200
*September 25, 2014*

**Math**

0.0034 move decimal point two places to the left to divide by 100 in ten based number system.
*September 25, 2014*

**physics**

dv = 4 pi r^2 dr note(surface area * dr) dv/v = 4 pi r^2 dr / (4/3) pi r^3 =3 dr/r
*September 25, 2014*

**physics see question above**

been there, done that
*September 25, 2014*

**Physics**

first drop the ball to see how long it is in the air 7.5 = 4.9 t^2 solve for t now horizontal problem u t = 9.5 u = 9.5 / t
*September 25, 2014*

**physics**

a + g = 7 + 9.8 = 16.8 m/s^2 F = 15 (16.8) = 252 N , bag tears
*September 25, 2014*

**physic**

F = k Q1 Q2 / d^2 where k = 9 * 10^9
*September 24, 2014*

**physics**

a = - 9.8 m/s^2 v = Vi + a t = 0 - 9.8 t h = Hi + Vi t -(9.8/2) t^2 0 = Hi + 0 (3) - (9.8/2)(3)^2 4.9 (9) = Hi Hi = 44.1 meters high
*September 24, 2014*

**History on Middle Ages(PLEASE HELP NOW)**

They had religious issues? I thought those were pre-decided in Rome :)
*September 24, 2014*

**Math**

well, surely x = -5 then y = 4
*September 24, 2014*

**statistics**

mean = 2.34 sd = .2 z = + or - .03/.2 look for probability of being within z = +/- .15 of mean
*September 24, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html
*September 24, 2014*

**Physics MCAT, Help please**

original momentum = 6 * 4 = 24 final momentum = 2 * 8 + V * 4 16 + 4 v = 24 4 v = 8 v = 2 m/s
*September 24, 2014*

**Math**

all components the same x i + x j + x k d = sqrt (3 x^2 ) = x sqrt 3 so if d = 1 x = sqrt(3) /3 so (sqrt 3/3)(i + j + k)
*September 23, 2014*

**Science**

(-4+8)/2 = 2
*September 23, 2014*

**Physics**

x = Xi + Vi t + (1/2) a t^2 4200 = 0 + 7.2 t + (1/2) a t^2 but t = 4 * 60 = 240 seconds so 4200 = 7.2(240) + .5 a (240)^2 solve for a then v = Vi + a t v = 7.2 + a (240)
*September 23, 2014*

**math**

(.2)gal/.08 shed = 2.5 gal /shed 2.5 gal/shed * 4 sheds = 10 gallons
*September 23, 2014*

**Math**

-1^3 = -1 (--2^4) = -2^4 = -16 5*-1*-16 = 80
*September 23, 2014*

**Math**

4.5 * 175/3
*September 22, 2014*

**math**

she painted 3/4 of 1/3 = 1/4 of the total wall what was left is 1/3 -1/4 = 4/12 -3/12 = 1/12 is bare still
*September 22, 2014*

**physics**

100 + 273 = Th 60 + 273 = Tc 100 * (Th-Tc)/Th
*September 22, 2014*

**Physics HUH ????**

Perhaps mass 2 is hanging from a pulley on earth and mass one is sliding on a frictionless horizontal table? If so force = m2 g mass accelerated = (m1+m2) F = m a m2 g = (m1+m2) a
*September 22, 2014*

**Math**

14+2m = 4m - 16 subtract 2 m both sides 14 = 2 m - 16 add 16 both sides 30 = 2 m multiply both sides by (1/2) 15 = m ================================ 4(x +2) = 14 - 2(3 - 4x) 4 x + 8 = 14 - 6 + 8 x 8 + 6 = 14 + 4 x 0 = 4 x x = 0 =========================== Eight subtracted ...
*September 22, 2014*

**Basic English - can not see underlines**

"for" in "for all" is one if underlined
*September 22, 2014*

**college physics**

average speed during crash = 3.75/2 so time to stop = .794 / (3.75/2) acceleration = change in speed / change in time or a = (0 - -3.75) / [.794 / (3.75/2) ] and F = m a = 52.2 a
*September 22, 2014*

**English**

6. Do you mix father up with turpentine before you paint? Perhaps: Father and I are going to paint the walls. 10. Does the janitor's office fit in the garbage can? Perhaps: I am going to throw garbage into the garbage can near the janitor's office.
*September 22, 2014*

**What is the degree of this polynomial?**

You are welcome :)
*September 22, 2014*

**What is the degree of this polynomial?**

1+2+3+2 = 8
*September 22, 2014*

**math**

50*20 = 1000 square feet so we use 1680/1000 = 1.680 ft on pool 1.680 * 12 = 20.16 inches used but there is an easier way 30 in * (2100/1000) * .4*.8 = 20.16 in
*September 21, 2014*

**math**

1/8 + x = 1/4 x = 1/4 - 1/8 x = 2/8 - 1/8 x = 1/8 but I bet you already knew that 1/8 + 1/8 = 1/4 :)
*September 21, 2014*

**Physics**

that is what you said. A mass of 10 kg is a weight of 98.1 Newtons
*September 21, 2014*

**Physics**

weight = 10 * 9.81 = 98.1 Newtons = normal force max friction force = .3 * 98.1 Newtons Of course we are not allowed to push down on it :)
*September 21, 2014*

**Hey, I just did this**

but here is another reply from another teacher http://www.jiskha.com/display.cgi?id=1202595476
*September 21, 2014*

**PHYSICS**

LOL, again ? R = A V = L^2 L/T P = F/A = m L/T^2 / L^2 P = m L/ (T^2L^2) m = rho L^3 P = rho L^3 /(T^2 L) P = rho L^2/T^2 = rho v^2 4 by the way this does not give us the sign and rho is M/L^3 but is constant in the usual incompressible fluid problem
*September 21, 2014*

**Physics I**

v = Vi + a t here v = Vi - 9.81 t
*September 21, 2014*

**Physics I**

our acceleration is 9.81 DOWN, negative so our UP speed decreases g = -9.81 m/s^2 gravity does not push UP no matter if you are going up or down
*September 21, 2014*

**Physics I**

aaarrrggghhhh !!!! g is g is g is g = -9.81 m/s^2 so d when you throw a ball up, its speed up decreases until it stops ! The acceleration is 9.81 down until it comes back down and hits the ground.
*September 21, 2014*

**Physics**

u = 15 forever Vi = -20 h = Hi + Vi t + (1/2) a t^2 0 = Hi - 20 t - 4.9 t^2 but t = 4 so solve for Hi, initial height in 4 seconds at 15 goes 60 meters where is the basket at 4 seconds? h basket = Hi - 80 d = sqrt (60^2 + h basket^2)
*September 21, 2014*

**physics**

u = 22 cos 53.6 forever Vi = 22 sin 53.6 v = Vi - 9.8 t at top v = 0 0 = 22 sin 53.6 - 9.8 t solve for t, time to top h = 0 + Vi t - 4.9 t^2
*September 21, 2014*

**physics**

u = horizontal speed = 14.9 forever now vertical problem, simply drop from 7.05 m -h = -(1/2)gt^2 7.05 = 4.9 t^2 t = 1.2 seconds to fall how far horizontal in 1.2 seconds? x = 14.9 * 1.2
*September 21, 2014*

**Algebra**

average base = (3b-4+b)/2 = 2b-2 (2b-2)(b/2) = 210 b^2-b-210 = 0 (b-15)(b+14) = 0 b = 15 3b-4 = b/2 =
*September 21, 2014*

**physics**

t1 = 280/88 t2 = 210/75 all south so v average south = (280+210)/(t1+t2)
*September 21, 2014*

**physics**

change in x speed = 6.5 cos50-4.2cos34.5 change in y speed = -6.5 sin50-4.2sin34.5 ax = change in x speed/2 ay = change in y speed/2 a = sqrt (ax^2+ay^2) A = angle of a above horizontal tan A = ay/ax
*September 21, 2014*

**physics**

Vi = 0.43 v = Vi + a t v = 0.43 + 3(5)
*September 21, 2014*

**physics**

That is half a g for 5 minutes, way too gigantic but anyway v = Vi + a t here t = 5 * 60 = 300 seconds
*September 21, 2014*

**physics**

a = change in velocity / change in time = (6.5 -1.2)/25
*September 21, 2014*

**statistics**

http://davidmlane.com/hyperstat/z_table.html
*September 21, 2014*

**physics**

Boat 1 north velocity as seen from boat 2 = boat 1 north speed - boat 2 north speed 2.2 cos 47 = .745 - boat 2 north Boat 1 east as seen from boat 2 = boat 1 east - boat 2 east 2.2 sin 47 = 0 - boat 2 east
*September 21, 2014*

**Math-HElP PLEASE??**

2.25a + 1.75(300-a) = 613.5
*September 21, 2014*

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