# Posts by Damon

Total # Posts: 29,823

**physics**

86 * 2.9 - 18 * 1.4 = (86+18)v

**algebra**

.03(x)+ .04(10,000-x) = 320

**Math**

agree 8/52 = 2/13 agree 4/52 = 1/13

**Maths**

z = 1000 - .01 x^2 - .02 y^2 dz = -.02 x dx -.04 y dy dz= -.02(60)dx - .04(1000)dy dz = -1.2 dx - 40 dy move in y direction , about 40 times as effective as x motion dz/dy = -40

**physics**

dv/dx = 6/4 = 1.5 m/s^2

**Physics**

ah, 160 cm = 63 inches 63 - 36 = 27 inch fall = 2.25 feet down fall so how fast did it leave hand moving horizontally at t = 0? m g h = (1/2) m u^2 u = sqrt (2 g h) u = sqrt (2 * 32 * 2.25) u = 12 feet/second horizontal speed That will not change until we hit the pins if ever ...

**Physics**

of course all shorter ranges have a lob angle and a straight shot angle :)

**Physics**

That is maximum range, no other angle will reach that range.

**Calculus**

oh, you want the derivative of the inverse function x = (y+9)/(y+3) dx = [(y+3)dy - (y+9)dy]/(y+3)^2 dx = -6 dy/(y+3)^2 dy/dx = (y+3)^2/-6

**Calculus**

did not see you wanted derivative either x = y^3 + 8 y - 3 dx = 3 y^2 dy + 8 dy dy/dx = 1/[3 y^2 + 8] if y = 6 1/[116]

**Calculus**

Sorry

**Calculus**

Do you mean f(x) = x^2 + 8 x - 3 ?? then to find f'-1 x = y^2 + 8 y -3 put in x = 6 y^2 + 8 y - 9 = 0 (y-1)(y+9) = 0 y = 1 or -9

**Calculus**

integral p dx of 88650 dx (3x+396)^-1 let z = 3x+396 then dz = 3 dx and I have 88650 (dz/3)/z or 29550 dz/z = 29550 ln z if x = 40, z = 120+396 = 516 if x = 50, z = 150+396 = 546 so 29550 [ln 546 - ln 516] = 29550 (.0565) = 1670 divide by 50-40 = 10 p average = 167...

**Physics**

d = (1/2) a t^2 = 45.6 You know a, solve for t v = a t

**Civic Education**

LOL - as long as the private parties are not "super delegates".

**Math**

h1 = 6 + 5 t h2 = 51 - 2 t when is h1 = h2 ? 6 + 5 t = 51 - 2 t 7 t = 45 t = 6 3/7 seconds

**math**

multiply everything by 4 4 * 2/3 = 8/3 = 2 2/3

**Science**

P = i V 60 = i (120) i = .5 amps V = i R R =120/.5 = 240 Ohms or P = V^2/R so R = 120^2/60 = 240 Ohms

**math**

Because it tells you how unpredictable a given sample might be. If you look at ages of children the average might be 10. If they are all in grade five they might all be pretty close to five. However if they are in classes from kindergarten to high school sophmores they might ...

**Physics C: Mechanics**

12 pi = (1/2) alpha (1.2)^2 so solve for alpha a = acceleration down of mass = r alpha = .05 alpha so 1 g - T = 1 a T = 1(g-a) Torque = .05 T = I alpha solve for I

**Physics C: Mechanics**

hollow cylinder I = m r^2 m a = m g sin A - torque/r m a = m g sin A - m r^2 alpha /r a = g sin alpha - r alpha but r alpha = a so a = (1/2) g sin A --------------------------------- solid sphere I = (2/5) m r^2 force down = m g sin A again force up * r = I alpha ma = m g sin ...

**Math (Algebra)**

then a = (60-b) .2(60-b) + .4 b = 18 12 - .2 b + .4 b = 18 .2 b = 6 b = 30 a = 30

**Math (Algebra)**

You are seriously right in your equations.

**Physics**

Ke at start = .5 (.125) 28^2 = 49 Joules .7 * 49 = 34.3 Joules = m g h = .125 * 9.81 * h so h = 28 meters

**Math**

n boys and n girls so 2 n total 3 n/5 + n/2 did not go that is 6 n/10 + 5 n/10 = 11 n/10 did not go 11 n/10 / 2n = (11/20) did not go

**Math**

80/6 = 13.3 so say she buys 13 * 5 = 65 then she gets 65/5 = 13 free which is 78 so she needs to buy 2 more 65 + 2 = 67

**L'Hospital's Rule and Indeterminate Forms**

Hmmm, as far as I know it applies only to 0/0

**Math**

patience, patience , plug and chug

**Math**

n marbles n/3 ---> Alvin 2 n /3 ---> J and S (5/8)(2n/3) ---> J so (3/8)(2n/3) ----> S which is (1/4)n

**Math**

y = 44.82 + .55 x In other words none of the above

**math**

2 n/3 + 72 = 1.20 n 2 n + 216 = 3.6 n 1.6 n = 216 n = 135 1*3*5 = 15

**Chemistry**

2HCl + Ca(OH)2 ---> 2 H2O .8 liters *.3 mol/liter = .24 mol Ca(OH)2 so we need .48 mols HCl .48 mol * 1000 ml/2 mol = 240 mL

**Chemistry**

1/3 cup = 145/3 = 48.3 kcal 48.3 kcal * 60 min/195 kcal = 14.8 minutes

**Maths**

You are welcome.

**Wicked hard :)**

even for a contest.

**Maths**

sum for the 7 over 10 must be divisible by 7 and from 77 to 140 by sevens 77, 84 , ...... 105 , 112 ..... 140 that sum + 2*8+9 or 25 must be divisible by 10 LOL 105 !!! 105 + 25 = 130 130/10 = 13

**Math**

Class 4—Greater than 6350 kg. to 7257 kg. (14,001–16,000 lbs.) If you increase the weight of a 14,000 pound truck by 4,000 pounds it will be MORE THAN 16,000 pounds

**Math**

[(x-24)/2 ] after Keri [(x-24)/4 ] after firemen [(x-24)/4 ] (1/3) after policeman = 7 so [(x-24)/4 ] = 21 (x-24) = 84 x = 108 ================ ================ check (108 - 24 /4 = 21 * 1/3 = 7 sure enough

**Math**

75/105 I think.

**typo ?**

Maybe you mean A(t) = 500 e^-(.044 t) ???????? A(20) = 500 e^-.88 = 500 * .415

**physics**

power in watts = energy in Joules / time in seconds

**PHYSICS**

I thought internal energy was usually called U Q is like heat flowing into a pot from the flame beneath W is like a piston moving and pushing a connecting rod U is like the water in the pot turning from cold to hot, storing energy provided by the flame beneath

**Physics**

for starters: gasoline engine burning generates heat, which radiates off into space from the surface of the engine and in the exhaust gasses. That is part of the efficiency of the thermodynamic cycle in the piston cylinders friction in bearings, gearing, crankshaft/bearings ...

**physics**

Yes, the air drag on the rain drop equals the gravitational force at fairly low speed. The important thing is: Force down = constant*volume Force up = constant * area so force down/force up = constant* L^3/L^2 = constant times length measurement for bodies of similar geometry ...

**Trigonometry**

3,4,5 right triangle sin T = 3/5 cos T = 4/5 tan T = 3/4

**Linear Algebra**

Yes because you can make V3 out of a linear combination of V1 and V2 V3=-3V1+2V2 that means that all three lie in a two dimensional plane. We could express all three as a linear combination of two orthogonal vectors in that plane.

**math**

p = pigs p + c = 61 c = 5 + 3 p c = (p/2)7 - 2 ====================== 2 c = 7 p - 4 2 c = 10 + 6 p so 7 p - 4 = 10 + 6 p p = 14 c = 47 h = 2 =============== check total = 63

**You do some**

Hey, I am not going to do all your work for you. This is the same idea as the one I did.

**chemistry**

.03 / 4 = .0075 mols of KNO3 needed .0075 * 101 g/mol = .758 grams

**Math**

4.6875 buses are needed but that does not work out very well, so we will need between 4 and 5 which means five if we are to take everyone because four buses only hold 4*32 = 128 people However five buses hold 5*32 = 160 so we will have 160 - 150 = ten seats empty

**physics**

from left end moments 5*200 + 500*10 + 80*2 = total load * cg from left total = 200 +300 + 500 + 80 = 1080 1080 x = 6160 x = 5.7 m

**Physics**

Why are you using conservation of energy? It is going up in smoke here. Use F=m a. average speed during stop = (7+0)/2 = 3.5 m/s so time to stop = 1.5 / 3.5 = .4286 seconds v = Vi + a t 0 = 7 +a(.4286) a = -16.3333 m/s^2 same force in second case, same mass so same ...

**Math**

h^2 + d^2 = 22^2 h/d = 4 or less 16 d^2 + d^2 = 22^2 17 d^2 = 22^2 d = 5.336 then h is limited to 4 d = 21.3 feet

**calculus**

y = f(e^t/(e^t+1)) dy/dt = dy/dx * dx/dt chain rule = dy/dx * d /dt [ e^t/(e^t+1) ] = dy/dx [ (e^t+1)e^t - e^2t ]/(e^t+1)^2 now what is x(1-x) ? [e^t/(e^t+1)][1-e^t/(e^t+1)] = [ e^t(e^t+1)- e^2t]/(e^t+1)^2 The same !!!

**Physics - Buoyant Force Question**

:) I just Googled: murdered by roman soldier on beach in Sicily and it worked immediately:)

**Physics - Buoyant Force Question**

Hint - He was murdered by a Roman soldier on a beach on his home island of Sicily.

**no way**

Some of these are very easy. What are your answers?

**Ms sue plz help**

http://study.com/academy/lesson/hamilton-and-the-federalists-vs-jefferson-and-the-republicans.html

**Physics**

Resistance is cut to 1/4 of original HOWEVER resistivity is a function of material. It does not change with geometry so (c) remains the same. http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html

**Nonsense**

A. Use one name and type question once. B. Type entire question. Kinetic energy where? when? Potential energy is m g h so you can find h, the cliff height, easily. You could therefore find the kinetic energy at the bottom due to falling easily. However you have no idea what ...

**More needed**

A = 1000 if t is years after 2016 however without knowing a, can not do.

**Calculus**

can 3-t = t/2 ? only if 1.5 t = 3 t = 2 now when t = 2 2 + 2*2 = 2 + 3*2 whoops, no way

**Calculus**

red: xr = 3 - t yr = 2 + 2 t zr = 6 + 2 t black: xb = t/2 yb = 2 + 3 t zb = 2 + t at t = 0 xb - xr = -3 yb - yr - 2-2 = 0 zb - zr = 2-6 = -4 so d = sqrt(9+16) = 5 answer part a)

**Physics**

quick check using 10 for g 8 = 20 - heat heat is about 12

**Math, Precalc**

A bearing by the way is the direction of something from you. For example that lighthouse bears 10 degrees off our starboard bow or 27 degrees magnetic. The direction you point the fishing boat is heading.

**Math, Precalc**

Oh the time = 14.2/2 = 7.1 hours

**AAARRRGGGHHH**

A fishing boat leaves port at 4 KNOTS at a HEADING of 80? for 3 hours, then turns to a HEADING of 0? at 3 KNOTS for 4 hours, and finally changes to a HEADING of 200? at 6 KNOTS for 5 hours. At this point, the boat heads directly back to port at a speed of 2 KNOTS. Find the ...

**pre-calculus**

(3x+9)(x+3)/ [(x-5)(x+2)] in the numerator I used 3x+9 instead of x+3 so that as x goes to infinity the fraction goes to 3x^2 + little stuff /x^2 + little stuff ---> 3

**no equal sign, no parenthese**

I have no idea what is numerator and what is denominator and you can not solve an expression.

**Physics**

U = hor speed = 30 cos 60 = 15 Vi - initial ver speed = 30 sin 60 = 26 get time upward v + Vi - 9.81 t 0 = 26 - 9.81 t at top t = 26/9.81 that is half total time range = 2 * 15 * 26/9.81

**Hey, scroll down**

I just did this

**MATH - PLEASE HELP!!**

L = 2 w - 3 and L w = 65 so L = 65/w 65/w = 2 w - 3 65 = 2 w^2 - 3 w 2 w^2 - 3w - 65 = 0 (w+5))(2w-13) positive w = 13/2 = 6.5 etc

**PE**

Do you really think warm up is not important. It sure is for those of us on Medicare :)

**sorry, no way**

Whoever wrote this problem assumed that the sled would have a velocity component of 11 m/s in the downwind direction due to the wind. However a sled (or a ship} is not an airplane or a balloon. if nothing else is pushing it, the wind in fact might not move it at all. The ice ...

**maths**

6 * 9 = 54 cm 10 mm/cm so 540 mm

**Calculus**

add y to both sides of the top equation. but I would do it by elimination, subtract and x is gone.

**Scientific Notation**

No, number between 1 and ten 15 * 10^7 = 1.5 * 10^8

**Rate of Change -Math**

n = number of trial passes p = total pay for day p = 20 + 5 n

**Trig**

u is in first quadrant tan of angle above x axis is 2/7 v is on -y axis so the angle between them is 90 + tan^-1(2/7)

**science**

A = |f1| B = |f2| answer = | A - B |

**sorry, do not understand notation**

do you mean 4* integral dx/(2x+3) or what?

**Math**

10/100 * 100 = 10%

**Science**

16 each way two 16 ohm resistors in parallel 1/R = 1/16 + 1/16 = 1/8 LOL, 8

**Calculus**

1990 - 1626 = 364 (I see where this is going :) 1.07^364 = 4.9624 *10^10 !!!!!! times 24 = 1.19 * 10^12 their return at 7% is far better 1.19 * 10^12 - 2.52 * 10^7 LOL, forget it. 25.2 billion is not even in the ball game.

**math**

n sold originally at p 32 n/27 sold later at 5 p/8 original rev = n p final rev = (32/27)(5/8) n p so (32/27) (5/8) = 20/27

**no way**

1 kg of this fruit costs 300 dollars?

**math**

maybe you mean sqrt (144 + 6^2) ??? that is sqrt (144+36) = sqrt 180 = sqrt (9* 20) =sqrt (9*4*5) = 3*2 sqrt 5 = 6 sqrt 5 = 13.41640786

**math**

concrete: 0.14 x + 0.06 (150) = 0.11 ( x + 150)

**math**

2^(84/6) = 2^14 = 16384

**algebra connections**

every year multiply by 1.025 so 5250 * 1.025^10

**algebra**

100 * 1.02^5 assuming you mean 2% per hour if it is per minute it would be 100 * 1.02 ^300

**Physics**

say they are d = 1 F = k (4)(-2)/1^2 = -8 k attracting later each has average (4-2)/2 = 1 in other words 10 microc each but now they repel (same charge) F = k (1)(1)/1^2 = k -8/+1 = -8

**PHYSIC**

speed = 100 m/s? H = 150 m ? upward trip, t = half flight time 0 = Vi - 9.81 t t = Vi/9.81 150 = Vi t - (1/2)(9.81) t^2 150 = Vi^2/9.81 - (1/2)(9.81)(Vi^2/9.81^2) 150 = Vi^2 / 4.9 Vi = 27.1 m/s then t = 27.1/9.81 = 2.76 going up plus another 2.76 down ---> 5.53 seconds ...

**Maths**

7*10 + 2*1 + 7/10 + 1/100

**need radii**

120 = speed of bucket * radius of handle/radius of barrel

**PHYSICS**

omega = v/r = 15/.33 radians/second .175 * omega

**Calculus**

e^(0 + pi i) = e^0 (cos pi + i sin pi) = 1 (-1 +0 ) = -1 so e^(i pi ) =-1 or e^(i pi) + 1 =0

**Physics**

3 liters N2 to 9 liters H2 9/3 = 3 NH3

**math**

tan 6 = 27,000 /x